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EANS TRAINING COURSE
VASCULAR NEUROSURGERY
The EANS acknowledges support from SPONSORS Codman Brainlab Setred
TALLINN, ESTONIA 20th – 24th February 2011
Editors: Vladimír Beneš, Susie Hide and Toomas Asser
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EANS COURSE - TALLINN
VASCULAR NEUROSURGERY
20-24 FEBRUARY 2011
EANS COURSE TALLINN
VASCULAR NEUROSURGERY 20TH-24TH FEBRUARY 2011 Editors: Vladimír Beneš, Susie Hide, Toomas Asser
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EANS COURSE - TALLINN
VASCULAR NEUROSURGERY
20-24 FEBRUARY 2011
PROGRAMME
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EANS COURSE - TALLINN
VASCULAR NEUROSURGERY
20-24 FEBRUARY 2011
SOCIAL PROGRAMME AND ADDITIONAL EVENTS Saturday 12.00 - 21.00 16.00 – 19.15 20.00 onwards
Registration: Meriton Grand Hotel: lobby Part 1 Exam: KJ Peterson Please arrive at 1530 to register for the exam Welcome Reception: Piano Bar, Meriton Grand Hotel
Sunday From 07.30 12.45 19.40 20.00
Registration: Meriton Grand Hotel - Piano Bar Training Committee Meeting: CR Jakobsen II Assemble in hotel lobby for transfer to Olde Hansa Restaurant Welcome dinner in Olde Hansa Restaurant Vana turg 1, Tallinn Tel: +372 627 9020 www.oldehansa.ee/?id+10693
Monday 12.45 19.40 20.00
Training Committee Meeting: CR Jakobsen II Assemble in hotel lobby for transfer to Zelluloos Bowling Centre Bowling and dinner at Zelluloos Bowling Centre Tartu mnt 80B and 80D (all one building) Tel: +372 681 0881/ +372 641 1022
Tuesday 15.30 19.40 20.00
Free afternoon and evening for trainees. Please refer to our suggestions as to how to spend your evening Faculty only – Assemble in hotel lobby for transfer to Dominic Restaurant Faculty Dinner: Hotel Dominic Vene 10, Tallinn Tel: +372 641 0400 www.restoran.ee/index_eng.html
Wednesday 12.40 19.40 20.00
Training Committee Meeting CR: Jakobsen II Assemble in hotel lobby for transfer to Estonian Art Museum Drinks and dinner at Estonian Art Museum KUMU Weizenbergi 34, Valge 1, Tallinn Tel: +372 602 6001 www.ekm.ee/eng/ekm.php
Thursday 20.00 20.30
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Welcome cocktail: Meriton Grand Hotel - Piano Bar Farewell Gala Dinner: Meriton Grand Hotel: KJ Peterson
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20-24 FEBRUARY 2011
LOCATIONS FOR SCIENTIFIC PROGRAMME All plenary sessions will take place in KJ Peterson. Disscusion Groups Rooms are shown on page 12-13 Workshop Rooms are shown on page 8 General Information We suggest that you call 1200 for taxi services in Tallinn (Tulika Takso) We very much hope that you will not need this, but if you do: Emergency number (fire and rescue service, ambulance) in Estonia is 112 Police: 110
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20-24 FEBRUARY 2011
Sunday 20th Aneurysms Chairman: 08.00 - 08.15
Asser Welcome and Introduction – course objectives
08.15 - 08.30 08.30 - 08.50 08.50 - 09.10 09.10 - 09.30 09.30 - 09.50
Introductory Information Epidemiology of aneurysmal SAH Grading and decision making in aneurysmal SAH Long term consequences of SAH Incidental and familial aneurysms, risk of rupture epidemiology
How I do it session: 09.50 - 10.00 ACOM 10.00 - 10.10 PCOM aneurysm (approaches) 10.10 - 10.20 MCA aneurysm (approaches) 10.20 - 10.30 A2 /3 aneurysms 10.30 - 10.40 Extradural anterior clinoid resection 10.40 - 10.50 Supraorbital eyebrow approach 10.50 - 11.10
Coffee Break
11.10 - 12.45
Discussion groups 1 - 8
12.45 - 14.00
Lunch and TC Meeting
Asser and Benes Hide Rinkel Poeata Jaaskelainen Rinne
Vajkoczy Bricis Benes Lehecka Roche Grotenhuis
See Pages 11-13
Chairman: Grotenhuis 14.00 - 14.20 Ruptured aneuysms beyond ISAT van Dijk 14.20 - 14.40 Complications of SAH Vajkoczy 14.40 - 15.45 RT Aneurysms Vatter, Andreou, Hernesniemi, Chapot, Vajkoczy How I do it session: 15.45 - 15.55 Upper VB aneurysm (approaches) 15.55 - 16.05 Lower VB aneurysm (approaches) 16.05 - 16.15 Giant aneurysms – Anterior circulation 16.15 -16.25 Far Lateral and Surgical Approaches to VB ANs 16.25 - 16.35 Giant aneurysms – Posterior circulation 16.35 - 17.00
Coffee Break
17.00 - 18.35
Discussion groups 1 - 8
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Hernesniemi Vatter Vatter Getch Hernesniemi
See Pages 11-13
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Monday 21st AVMs Chairman: Roche 08.10 - 08.30 Intracranial vascular anatomy and embryology 08.30 - 08.50 Classification, haemodynamics and natural history 08.50 - 09.10 Surgical treatment of AVMs 09.10 - 09.30 Endovascular treatment of AVMs 09.30 - 09.50 Radiosurgery for AVMs 09.50 - 10.10 Comprehensive management of AVMs How I do it session: 10.10 - 10.20 Surgery for an AVM 10.20 - 10.30 Surgical techniques in AVM 10.30 - 10.40 Endovascular treatment 10.40 - 11.10
Coffee Break
11.10 - 12.45
Discussion groups 1 - 8
12.45 - 13.45
Lunch and TC meeting
Destrieux Laakso Schaller Chapot Kemeny Getch
Benes Hernesniemi Chapot
See Pages 11-13
Chairman: Juhler 13.45 - 14.45 RT: Can we Juhler, Chapot, Schaller, Kemeny, Laakso reach an algorithm/ guideline for AVM treatment? 14.45 - 15.05 Intracranial venous pathology, including fistulas Roche 15.05 - 15.25 Cerebrovascular disease in children Juhler 15.25 - 15.45 Cavernomas Niemela 15.45 - 16.05 Extra and intracranial dissections Brennum How I do it session: 16.05 - 16.15 Cavernomas – deep structures 16.15 - 16.25 Brainstem cavernomas (various approaches) 16.25 - 16.35 Non-eloquent cavernomas 16.35 - 17.05
Coffee Break
17.05 - 18.40
Discussion groups 1 - 8
Hernesniemi Gruber Netuka
See Pages 11-13
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Tuesday 22nd Chairman: Asser Special lectures 08.30 08.50 09.20 10.20
Ludvig Puusep – a pioneer of neurosurgery Innovative e-and i-Solutions at Work in Estonia Non verbal communication Ethics: Brief Interactive Session
10.35 – 11.00
Coffee Break
11.00 – 15.25
Workshops
Group
11.00 - 11.40
11.45 – 12.25
12.30 – 13.10
A B C D E F
CR Jakobson I FREE FREE FREE V Panso CR Jakobson II
CR Jakobson II CR Jakobson I FREE FREE FREE V Panso
V Panso CR Jakobson II CR Jakobson I FREE FREE FREE
Group
13.15 - 13.55
14.00 – 14.40
14.45 – 15.25
A B C D E F
FREE V Panso CR Jakobson II CR Jakobson I FREE FREE
FREE FREE V Panso CR Jakobson II CR Jakobson I FREE
FREE FREE FREE V Panso CR Jakobson II CR Jakobson I
Workshop Topics: CR Jakobson I Codman – topic to be confirmed CR Jakobson II BrainLAB: topic to be confirmed V Panso SETRED: Intuitive 3D in Neurosurgery (no glasses) 15.30 onwards Videos
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Asser Usk Westerhof Verlooy
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Wednesday 23rd Other vascular malformations and haematomas Chairman: Kushel 08.00 - 08.20 Monitoring in CV surgery 08.20 - 08.50 Embryology of AVM and DAVM 08.50 - 09.10 Treatment of Cranial DAVM – both perspectives 09.10 - 09.30 Spinal AVM and DAVM 09.30 - 09.40 Spinal cord cavernomas 09.40 - 10.00 Diagnostics in ICH 10.00 - 10.20 Intracerebral and intracerebellar hematomas 10.20 - 10.40 STICH studies 10.40 - 11.00
Coffee Break
11.00 - 12.35
Discussion groups 9 - 16
12.35 - 14.00
Lunch and TC meeting
Sala Cognard Van Dijk Rohde Kushel Marklund Buki Mendelow
See Pages 11-13
Ischaemia Chairman: Marklund 14.00 - 14.20 Vascular anatomy/ Cerebral blood flow/ Brennum physiology and cerebral ischaemia 14.20 - 14.40 Intracranial stenotic disease – endovascular point Cognard 14.40 - 15.00 Reconstructive surgery in cerebral ischaemia Benes 15.20 - 15.40 Place, role and techniques for cerebral by-pass surgery Regli 15.00 - 15.20 Treatment of Acute cerebral ischaemia Smolanka 15.40 - 16.00 Surgery in ‘malignant’ cerebral infarction Mendelow How I do it session: 16.00 - 16.10 Carotid endarterectomy 16.10 - 16.20 Making an extra-intracranial by-pass 16.20 - 16.50
Coffee Break
16.50 - 18.25
Discussion groups 9 - 16
Benes Regli
See Pages 11-13
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Thursday 24th Haematomas contd. 08.00 - 08.30
Making oral and poster presentations
Mooij
Chairman: Smolanka How I do it session: 08.30 - 08.40 Intracerebral hematoma 08.40 - 08.50 Intracerebral haematoma 08.50 - 09.00 Intracerebellar haematoma (adults) 09.00 - 09.10 Intracerebellar haemorrhage (children) 09.10 - 09.20 Decompressive craniotomy for supratentorial ischaemia 09.20 - 10.30
Trainee lectures
10.30 - 11.00
Coffee Break
11.00 - 12.35
Discussion groups 9 - 16
12.35 - 14.00
Lunch
Chairman: Special session: Sub-specialisation 14.00 - 14.20 Introduction and voting 14.20 - 14.35 Spine 14.35 - 14.50 Onco 14.50 - 15.05 Vascular 15.05 - 15.20 Functional 15.20 - 15.35 Radiosurgery 15.35 - 15.50 Pediatric neurosurgery 15.50 - 16.05 Skull Base 16.05 - 16.10 Voting 16.10 - 16.30 Summary 16.30 - 16.50
Coffee Break
16.50 - 18.25
Discussion groups 9 - 16
18.30 - 19.00
Course evaluation
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Mendelow Smolanka Thome Hinojosa Shoshan
Buis, Ganau, Jetzer, Muroi, Sauvaget, Sherif, Türkoğlu See Pages 187
See Pages 11-13
Beneš Timothy di Meco Regli Broggi Kemeny TBA Roche Marsh
See Pages 11-13
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Discussion Groups Sunday/Monday 1. Clip or coil?
Vajkoczy/Chapot
2. Intensive care in vascular disease
Marklund/Meling
3. Complications of aneurysm management
Poeata/Andreou
4. Management of non eloquent cavernomas
Selviaridis/Grotenhuis
5. Decision making in Brain stem cavernomas
Kushel/Gruber
6. AVMs - choice of treatment 7. Haematomas in the elderly - cortical 8. Multiple aneurysms
Benes/Roche d‘Avella/Bricis Schaller/Niemela
Wednesday/Thursday 10. Management of intracranial haematomas – deepseated
Shoshan/Vara Luiz
11. Cerebral revascularisation
Regli/Thome
12. Posterior fossa haematoma / infarction
Buki/Verlooy
13. Decompressive surgery for stroke
Mendelow/Brennum
14. Management of IVH
Marklund/Akalan
15. Occlusive carotid disease
Netuka/Smolanka
16. Paediatric vascular disease
Juhler/Hinojosa
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DISCUSSION GROUP TIMETABLE AND ROOM ALLOCATIONS Sunday 20th February Group
Room
11.10 – 11.55
12.00 – 12.45
A B C D E F
KJ Peterson V Panso B Alver CR Jakobson II CR Jakobson I Grand Panorama
1 2 3 7 6 8
2 3 5 6 7 1
Group
Room
17.00 – 17.45
17.50 – 18.35
A B C D E F
V Panso B Alver CR Jakobson II CR Jakobson I Grand Panorama KJ Peterson
3 5 2 4 1 6
5 4 6 2 8 7
Group
Room
11.10 – 11.55
12.00 – 12.45
A B C D E F
B Alver CR Jakobson II CR Jakobson I Grand Panorama KJ Peterson V Panso
6 1 8 3 2 4
4 7 1 8 5 3
Group
Room
17.05 – 17.50
17.55 – 18.40
A B C D E F
CR Jakobson II CR Jakobson I Grand Panorama KJ Peterson V Panso B Alver
7 8 4 1 3 5
8 6 7 5 4 2
Monday 21st February
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Wednesday 23rd February Group
Room
11.00 – 11.45
11.50 – 12.35
A B C D E F
CR Jakobson I Grand Panorama KJ Peterson V Panso B Alver CR Jakobson II
9 15 11 10 14 16
15 11 12 14 10 9
Group
Room
16.50 – 17.35
17.40 – 18.25
A B C D E F
Grand Panorama KJ Peterson V Panso B Alver CR Jakobson II CR Jakobson I
11 12 15 13 9 14
12 13 14 15 16 10
Group
Room
11.00 – 11.45
11.50 – 12.35
A B C D E F
KJ Peterson V Panso B Alver CR Jakobson II CR Jakobson I Grand Panorama
14 9 16 11 15 13
13 10 9 16 12 11
Group
Room
16.50 – 17.35
17.40 – 18.25
A B C D E F
V Panso B Alver CR Jakobson II E Tubin Grand Panorama L Koidula
10 16 13 9 11 12
16 14 10 12 13 15
Thursday 24th February
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20-24 FEBRUARY 2011
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ABSTRACTS
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INDEX OF ABSTRACTS Sunday 20th Epidemiology of aneurysmal SAH
Rinkel
Page 19
Grading and decision making in aneurysmal SAH
Poeata
Page 24
Long term consequences of SAH
Jaaskelainen Page 31
Incidental and familial aneurysms, risk of rupture epidemiology
Rinne
Page 38
Ruptured aneuysms beyond ISAT
van Dijk
Page 44
Complications of SAH
Vajkoczy
Page 46
Monday 21st Intracranial vascular anatomy and embryology
Destrieux
Page 51
Classification, haemodynamics and natural history
Laakso
Page 58
Radiosurgery for AVMs
Kemeny
Page 65
Comprehensive management of AVMs
Getch
Page 71
Intracranial venous pathology, including fistulas
Roche
Page 77
Cerebrovascular disease in children
Juhler
Page 89
Cavernomas
Niemela
Page 94
Extra and intracranial dissections
Brennum
Page 100
Westerhof
Page 104
Sala Cognard Van Dijk Rohde Kushel Marklund Buki Mendelow Brennum
Page 107 Page 113 Page 126 Page 129 Page 133 Page 135 Page 144 Page 149 Page 156
Benes
Page 161
Tuesday 22nd Non verbal communication Wednesday 23rd Monitoring in CV surgery Embryology of AVM and DAVM Treatment of Cranial DAVM – both perspectives Spinal AVM and DAVM Video spinal cord cavernomas Diagnostics in ICH Intracerebral and intracerebellar hematomas STICH studies Vascular anatomy/ Cerebral blood flow/ physiology and cerebral ischaemia Reconstructive surgery in cerebral ischaemia
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Place, role and techniques for cerebral by-pass surgery Treatment of Acute cerebral ischaemia
20-24 FEBRUARY 2011 Regli
Page 176
Smolanka
Page 180
Mooij
Page 185
Buis
Page 188
Systemic inflammatory response syndrome in sah and ich: new pathophysiological and therapeutics viewpoints.
Ganau
Page 190
Polymer coils for endovascular treatment of large aneurysms – primary results from an in vivo aneurysm model
Jetzer
Page 195
Systemic interleukin-6 levels in patients with perimesencephalic nonaneurysmal subarachnoid hemorrhage
Muroi
Page 196
Prevalence of severe neurovascular conflicts with the trigeminal nerve in asymptomatic patients.1.5 T MRI Cross sectional study of 216 trigeminal nerves
Sauvaget
Page 197
Computerized occlusion-rating: an objectively measured predictor of aneurysm re-rupture in ruptured embolized cerebral aneurysms
Sherif
Page 199
Refining the cadaveric reperfusion and angiography as a teaching tool: imaging the intracranial vasculature in cadavers
Türkoğlu
Page 200
Carotid endarterectomy in patients with contralateral carotid occlusion
Bombic
Page 201
The blood supply to the lateral wall of the cavernous sinus: a comparative study of the endoscopic and microsurgical perspectives
d’Avella
Page 202
Development and characterisation of an acellular porcine ureter with a view to producing a tissue engineered small diameter (70 / 75 years?) or in a moribund (?) condition. Acute aSAH is a complex systemic condition that requires neuroICU care by a dedicated team of neurointensivists, neurosurgeons, neuroradiologists and neuronurses. Thorough understanding of the natural course of aSAH as well as multimodality monitoring for its intracranial and extracranial complications are required. The management is directed to the prevention of further damage, e.g., 31
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from re-bleeding, hydrocephalus, increased ICP, seizures, electrolyte disturbances, cardiac and pulmonary dysfunction, and subacute development of delayed ischemic brain injury (Levine 2009, Bederson 2009).
12-month mortality and neurological morbidity In recent multivariate analyses of large aSAH cohorts, the subsequent outcome and mortality have been reported at 2 months, 3 months, 6 months, or 12 months after aSAH. Outcome measures have included the survival rate, the Glasgow Outcome Scale (GOS) or extended GOS, and the modified Rankin Scale. Independent risk factors have varied per cohort whether data on the patients’ clinical condition on admission or also from the neurointensive care period have been included (Rosengart 2007). Kuopio sIA Database contains 1657 consecutive patients admitted alive within 24 hours after aSAH to the between 1980 and 2007. The cumulative mortality rate was 27% at 12 months. Of 13 factors known after admission, age >65 years, H&H grades IV-V, intracerebral hemorrhage >15cm3, intraventricular hemorrhage, and severe hydrocephalus independently predicted the 12-month mortality. There was excess mortality due to aSAH for at least 12 months other causes of death became dominant. This suggests that the management mortality of aSAH should not given at less than 12 months (Karamanakos P, unpublished).
Individual prognostication for 12-month outcome after aSAH? Neurointensive care with advancing monitoring and interventional technology as well as nursing resources required is expensive per patient. The proportion of aged and moribund aSAH patients increases in ageing European populations. It is obvious that a single prognostic scale (e.g., Hunt & Hess scale, Glasgow Coma Scale, WFNS classification, Fisher Grade) carries insufficient amount of clinical data for accurate prediction of the individual risk of death or neurological outcome after aSAH. Prognosticators based on many variables from comprehensive and replicated aSAH databases are required for everyday outcome analysis (a) on the admission as well as (b) during the neurointensive care of individual aSAH patients, at least in the countries like Finland with equal and tax paid health care. Databases are already widely used in the intensive care units (see saps3.org).
Longterm sequelae after aSAH There are few published population-based data on the longterm excess mortality and excess neurological morbidity of aSAH survivors – as compared to matched catchment populations. Acute aSAH is a systemic condition that may affect the central nervous system and the cardiovascular system in several ways – such injuries are involved the 12-month outcome but their longterm impact has not 32
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been studied comprehensively. It is not known, e.g., how often the aSAH survivors would develop epilepsy, depression, dementia, shunt complications, hypothalamic and hypophyseal disorders requiring substitution, or neurovascular or cardiovascular events. Furthermore, the genomic variants behind the sIA disease (Yasuno 2010) as well as the acquired risk factors such as hypertension and smoking may sensitize the sIA patients to neurovascular and cardiovascular events in later life. All these may add to longterm excess mortality and morbidity.
1. Prevalence of aSAH survivors in population The number of patients alive after aSAH in a given time in a given population has not been assessed. The demographics of aSAH survivors are needed to allocate resources for their longterm follow up and prognostication.
2. Longterm excess mortality after aSAH In the International Subarachnoid Aneurysm Trial (ISAT) cohort, 1.413 one year survivors of aSAH from U.K. presented with 144 deaths in a mean of 9 years against 92 expected deaths from the standard death rates of England and Wales. There were 17 re-bleeds from the clipped or coiled aneurysms causing 9 deaths, and 6 cases of aSAH from de novo aneurysms causing 3 deaths (Molyneux 2009). Kuopio sIA Database contains 1.746 one-year survivors of aSAH (1980-2007) from the Eastern Finnish catchment population. Relative survival ratios were calculated as compared to the matched (gender, age, calendar time) catchment population. There was a 12% excess mortality at 15 years (Huttunen 2011). The causes of the long term excess mortality are heterogeneous, and more detailed analyses are required. There were lethal re-bleeds from 13 of the 1.440 clipped sIAs, two of the 265 coiled sIAs, and two from the 17 non-occluded sIAs, and 14 new lethal bleeds from other sIAs (Huttunen 2011).
3. Neurovascular events after aSAH The brain circulation may be altered by the occlusive therapies of the ruptured sIA, inadvertent occlusion of perforating arteries or major branches in its vicinity. Ischemic brain injury may develop at the acute phase (Zetterling 2010) or at the subacute phased as delayed ischemic neural damage (DIND), a major mechanism of longterm neurological morbidity. The aSAH survivors may develop a new aSAH from a failed occlusion of the ruptured sIA or new aSAH from an unruptured sIA already present at the time of first aSAH or from a de novo sIA later (Molyneux 2009, Huttunen 2011). However, the impact of aSAH on the brain arterial tree may predispose to later events, brain infarctions or intracerebral hemorrhages – at least in those aSAH survivors with hypertension at the time of aSAH or later – but no comprehensive data exists. 33
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4. Cardiovascular events after aSAH The complex sIA disease may predispose to other cardiovascular events in later life (Ronkainen 2001, Huttunen 2011). Acute aSAH is a complex systemic condition that strains the cardiopulmonary system as well (van der Bilt 2009), but it is not known what the longterm consequences are. In addition, the genomic constitution of aSAH survivors might predispose later to myocardial events.
5. Shunt dependent hydrocephalus (SDHC) after aSAH In 839 aSAH patients, the rate of SDHC was 19% with independent risk factors of age >50 years, Hunt & Hess grades 4 and 5, IVH (47%), and acute hydrocephalus (85%) on admission. In 580 aSAH patients, independent factors were admission glucose > 125 mg/dl, admission CT with bicaudate index >0.20, Fisher Grade 4, IV ventricle hemorrhage, and meningitis (Rincon 2010). Short-term epsilon aminocaproic acid to prevent ultra early re-bleeds may also increase the risk of SDHC (Harrigan 2010). In 585 aSAH patients with SDHC, the rate of shunt revisions was about 30%, and endovascular treatment was an independent factor (O'Kelly 2009). Instead, it is not known how SDHC would affect the longterm quality of life in terms of shunt failures and other complications.
6. Epilepsy after aSAH Published data on the occurrence of symptomatic epilepsy after aSAH, its compliance to anti-epileptic drugs (AEDs), and longterm mortality attributable to seizures are scarce. In the Kuopio sIA Database, 1.059 aSAH patients had been admitted between 1995 an 2007, and 117 (11%) developed symptomatic unprovoked seizures after one week from aSAH (Huttunen J, unpublished). In 547 aSAH patients, only 3% developed late epilepsy, >2 spontaneous seizures after the first week with an interval of >24 hours (Choi 2009).
7. Mood disorders and quality of life after aSAH The data from large longitudinal studies on health-related quality of life (HRQoL) in aSAH patients are limited (Meyer 2010). In 141 aSAH survivors living independently 2 to 4 years after aSAH, 67% reported fatigue, 32% anxiety and 23% depression (Visser-Meily 2009).
8. Alzheimer’s disease and dementia after aSAH Traumatic brain injury predisposes to Alzheimer’s disease (AD) in later life (Johnson 2010). Survivors of aSAH commonly experience deficits in memory, 34
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executive function, and language (Meyer 2010). Instead, there are no data on how often the survivors of aSAH in later life develop cognitive decline and AD as compared to matched catchment populations.
9. Hypophyseal insufficiency after aSAH Hypophyseal insufficiency is an underdiagnosed complication of aSAH in the neurointensive care. There are reports suggesting that later hypophyseal insufficiency may impair the quality of life after aSAH but this has not been studied in depth (Schneider 2007).
10. Concomitant systemic diseases with sIA disease Hypertension and diabetes 2 are important risk factors of brain infarction and intracerebral hemorrhage. In the Kuopio sIA Database, 1.060 aSAH patients had been admitted between 1995 and 2007, and as many as 608 (57%) had antihypertensive medication at the time of aSAH or later during the follow up (Lindgren A, unpublished). Curiouslty, diabetes type 2 does not appear a risk factor for the sIA disease, but the longterm risk of DM2 in aSAH survivors has not been studied. Autosomal dominant polycystic kidney disease that predisposes to the sIA disease by unknown mechanisms occurs in some 1% of aSAH patients.
Future directions Aneurysmal subarachnoid hemorrhage has been the domain of neurosurgeons, and the daily and published clinical practice has been focused to the preventation of re-bleeds and on the acute neurointensive care – unfortunate for the understanding of longterm sequelae of aSAH. This is corrected within comprehensive neurocenters that provide multimodality neurocare and follow up of the aSAH patients and build up databases for the overall prognostication of the sIA disease and aSAH.
Key references and recommended reading Yasuno K, et al. Genome-wide association study of intracranial aneurysm identifies three new risk loci. Nat Genet 2010;42:420-5. Ronkainen A, et al. Risk of harboring an unruptured intracranial aneurysm. Stroke 1998;29:359-62. Huttunen T, et al. Saccular intracranial aneurysm disease: distribution of site, size, and age suggests different etiologies for aneurysm formation and rupture in 316 familial and 1454 sporadic eastern Finnish patients. Neurosurgery 2010;66:631-8.
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Feigin VL, et al. Risk factors for subarachnoid hemorrhage: an updated systematic review of epidemiological studies. Stroke 2005;36:2773-80. Feigin VL, et al. Worldwide stroke incidence and early case fatality reported in 56 population-based studies: a systematic review. Lancet Neurol 2009;8:355-69. van Gijn J, et al. Subarachnoid haemorrhage. Lancet 2007;369(9558):306-18. Levine JM. Critical care management of subarachnoid hemorrhage. Curr Treat Options Neurol 2009;11:126-36. Review. Bederson JB, et al. Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage. A Statement for Healthcare Professionals From a Special Writing Group of the Stroke Council, American Heart Association. Stroke 2009;40:9941025. Rosengart AJ, et al. Prognostic factors for outcome in patients with aneurysmal subarachnoid hemorrhage. Stroke 2007;38:2315-2321. Molyneux AJ, et al. Risk of recurrent subarachnoid haemorrhage, death, or dependence and standardised mortality ratios after clipping or coiling of an intracranial aneurysm in the International Subarachnoid Aneurysm Trial (ISAT): long-term follow-up. Lancet Neurol 2009;8:427-33. Huttunen T, et al. Long-term excess mortality of 244 familial and 1502 sporadic one-year survivors of aneurysmal subarachnoid hemorrhage compared with a matched Eastern Finnish catchment population. Neurosurgery 2011;68:20-7. Zetterling M, et al. Early global brain oedema in relation to clinical admission parameters and outcome in patients with aneurysmal subarachnoid haemorrhage. Acta Neurochir 2010;152:1527-33. Ronkainen A, et al. Evidence for excess long-term mortality after treated subarachnoid hemorrhage. Stroke 2001;32:2850-3. van der Bilt IA, et al. Impact of cardiac complications on outcome after aneurysmal subarachnoid hemorrhage: a meta-analysis. Neurology 2009;72:63542. Nam KH, et al. Risk of Shunt Dependent Hydrocephalus after Treatment of Ruptured Intracranial Aneurysms: Surgical Clipping versus Endovascular Coiling According to Fisher Grading System. J KoreanNeurosurg Soc 2010;48:313-8. Harrigan MR, et al. Short-term antifibrinolytic therapy before early aneurysm treatment in subarachnoid hemorrhage: effects on rehemorrhage, cerebral ischemia, and hydrocephalus. Neurosurgery 2010;67:935-9. Rincon F, et al. Predictors of long-term shunt-dependent hydrocephalus after aneurysmal subarachnoid hemorrhage. Clinical article. J Neurosurg 2010;113:77480. O'Kelly CJ, et al. Shunt-dependenthydrocephalus after aneurysmal subarachnoid 36
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hemorrhage: incidence, predictors, and revision rates. Clinical article. J Neurosurg 2009;111:1029-35. Choi KS, et al. Seizures and Epilepsy following Aneurysmal Subarachnoid Hemorrhage: Incidence and Risk Factors. J Korean Neurosurg Soc 2009;46:93-8. Meyer B, et al. Health-related quality of life in patients with subarachnoid haemorrhage. Cerebrovasc Dis 2010;30:423-31. Visser-Meily JM, et al. Long-term health-related quality of life after aneurysmal subarachnoid hemorrhage: relationship with psychological symptoms and personality characteristics. Stroke 2009;40:1526-9. Johnson VE, et al. Traumatic brain injury and amyloid-beta pathology: a link to Alzheimer's disease? Nat Rev Neurosci 2010 (Epub ahead of print). Al-Khindi T, et al. Cognitive and functional outcome after aneurysmal subarachnoid hemorrhage. Stroke 2010;41:e519-36. Schneider HJ, et al. Hypothalamopituitary dysfunction following traumatic brain injury and aneurysmal subarachnoid hemorrhage: a systematic review. JAMA 2007;298:1429-38. Inagawa T. Risk factors for the formation and rupture of intracranial saccular aneurysms in Shimane, Japan. World Neurosurg 2010;73:155-64.
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INCIDENTAL SACCULAR INTRACRANIAL ANEURYSMS (SIA) – EPIDEMIOLOGY AND RISK OF RUPTURE Jaakko Rinne MD PhD Director of KUH NeuroCenter Juha E Jääskeläinen MD PhD Professor Chairman Neurosurgery of Kuopio University Hospital, NeuroCenter, Kuopio, FINLAND Kuopio Intracranial Aneurysm Database (www.uef.fi/crc/ns) Finnish Intracranial Aneurysm Research Consortium (www.fiarc.fi)
Objectives 1.
To review the recent literature on the incidental sIAs.
2.
Focusing on the epidemiology of both sporadic and familial sIAs - and to present d ata o n t he p henotype o n a dmission o f u nruptured f amilial (n=148) and sporadic (n=385) vs. ruptured familial (n=168) and sporadic (n=1069) Eastern Finnish sIA cases from 1993 to 2007 in the K uopio Neurosurgery Database.
3.
Focusing on different factors affecting the risk of rupture of the sIA wall.
Review of recent relevant literature 1. Epidemiology of sIAs sIAs are acquired pouches that develop during life at the branching sites of major intracranial extraparenchymal arteries in the subarachnoid space, in the region of the circle of Willis and its tributaries. It is impossible to pinpoint the accurate percentage of carriers of unruptured sIAs in a population because that would require screening of large cohorts of different years of births by MR angiography. Some 2% of population develop sIA(s). Most of them are small and located in the anterior circulation. Most sIAs will go unruptured and unnoticed during life: 2% would indicate 2.000 carriers per 100.000 while the general i ncidence o f a neurysmal s ubarachnoid h emorrhage i s a bout 6 - 9 p er 100.000 per year. The sIA disease is a complex trait, like diabetes type 2 or Alzheimer's disease, affected by acquired risk factors and variants in the genome, and by their complex interactions. The prevalence of sIA is higher in women, increases wi th age, is associated with smoking, hypertension, excessive us e of alcohol, and previous aneurysmal SAH (aSAH). The strongest risk factor is belonging to an sIA family. The risk o f d eveloping s IAs i s a lso h igher i n a utosomal d ominant p olycystic k idney disease. It is not known, so far, by which cellular and molecular mechanisms these risk factors affect the formation of the sIA pouch (primary phenotype) and/or rupture of the sIA wall (secondary phenotype).
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Carriers of unruptured sIAs become unveiled during life mainly in four ways, with the following p roportions o f a ll u nruptured s IA c ases i n t he K uopio I ntracranial Aneurysm Database: •
incidental sIAs in neuroimaging for other reasons (59%).
•
incidental sIAs in screening of sIA family members (4%).
•
associated / incidental sIAs in 4-vessel angiographies of patients with aSAH from another sIA (35%).
•
symptomatic large sIAs (2% - median diameter 30 mm, range 9 - 60 mm).
Consequently, the frequency and demographics of the unruptured sIA carriers are affected by t he d iagnostic e fforts. I n t he K uopio D atabase, t he f ollowing characteristics were noted:
2. Risk of rupture The reported rupture risk of unruptured sIAs varies and is inconclusive – zero to 2.3% per year. A recent meta-analysis estimated an overall risk of about 1% per year . A variety of patient and aneurysm characteristics as well as a previous history of SAH from another aneurysm affect the risk. In studies with a mean follow-up time 10 years 1.3%. In a dynamic and complex disease like sIA, the risk of rupture may appear different if 1000 sIA carriers are followed up for one year rather than 100 sIA patients for ten years. In many follow up studies, the risk assessment is based on the assumption of constant risk. The natural history of sIA disease may involve time periods of sIA formation or accelerated growth – with an increased risk of rupture. Every sIA i s an individual lesion with varying geometry, size, location, and relation to surrounding vasculature in an individual patient with varying age, co-morbidities, and genomic constitution. 2.1. Size, shape and growth 39
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It is evident that the risk of rupture increases with the sIA size. Giant ones (>15 mm) carry an annual risk of 15%, those of 10 – 15 mm 5%, those of 5 – 9 mm 3%, and those 25cm H2O) should be confirmed during lumbar puncture in the lateral decubitus position, and the C SF composition should be normal. 3) Neuroimaging should reveal normal findings, without evidence of ventriculomegaly, intracranial lesions, or dural sinus thrombosis. 4) T here i s a n a bsence o f o ther c auses o f r aised. T he e xact p athophysiological mechanism is not known, however , various mechanisms have been considered: Increased CSF production, decreased CSF absorption, idiopathic brain swelling, and idiopathic intracranial venous hypertension. Clinically, IIH presents most commonly with headaches. Transient visual disturbances and pulsatile tinnitus are also experienced in about 70% of patients. P apilledema due to raised ICP is almost ubiquitous and rarely unilateral. In its absence, a diagnosis other t han IIH should be considered. V isual field loss is almost always present, although up to 25% of patients may not complain of any visual loss. Left untreated, there is a high risk of continued deteri oration and eventual blindness due to excessive papilledema. Radiological investigation is based upon MR imaging and MR venography. Suspicion
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of venous sinus s tenosis will lead to an angiogram to confirm this stenosis and record pressures in the pre- and the post-stenotic segment of the sinus. Ophtalmological workup evaluates the visual acuity and the visual field of patients, and includes an OCT. The most commonly used medical treatment is acetazolamide, a carbonic anhydrase inhibitor that can reduce ICP and intraocular pressure by decreasing C SF and aqueous humor production. Surgery is reserved for patients in whom medical therapy has failed. The C SF drainage can be done to decrease the ICP . Less commonly, optic nerve sheath fenestration can also be performed to improve visual function. Currently, there are no controlled, randomized trials comparing these surgical modalities to each other or to medical management. F ailure is common, occurring in up to 30% of patients. It is unclear whether the increased ICP may be a cause or consequence of the dural venous stenosis but stenosis of the transverse sinus has been found in up to 90% of cases in recent studies. Stenting of stenotic dural sinuses demonstrated in cases of IIH has shown promising results (up to 70% of resolution of papilledema). Selection of cases for stenting is based upon the demonstration of significant pressure gradient on angiogram.
Conclusions Origin and natural history of these venous disorders are gradually better understood. Technical improvements of microcatheter, guide wires, material of embolization and angiography (biplanar and three-dimensional rotational selective and superselective angiography) h ave c ontributed g reatly t o r ecent a dvances i n i nterventional neuroradiology. However there is still a significant room available for microsurgery and f or co mbined e ndovascular a nd s urgical i nterventions. T eam a pproach i s considered the standard for a successful management of these malformations.
References 1. Awad I . I ntracranial du ral a rteriovenous m alformations, I n: W ilkins & Rengachary, Neurosurgery, Wilkins Vol II, pp: 2519-2527, 1996 2. Barnwell SL & O’Neill OR. Lesions of cerebral veins a nd dural sinuses. In Youmans, Neurological Surgery, pp 1465 3. Barrow D L, S pector R H, B raun I F, e t a l. C lassification a nd t reatment o f spontaneous carotid-cavernous sinus fistulas. J Neurosurg 1985, 62: 248-256 4. Bowder J, Kaplan HA. Cerebral dural sinuses and their tributaries. Springfield IL: Charles C, Thomas, 1976 5. Cognard C, Gobin YP, Pierot L, Bailly Al, Houdart E, Casasco A, Chiras J, Merland
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JJ. Cerebral dural arteriovenous fistulas: clinical and angiographic correlation with a revised classification of venous drainage. Radiology 194:671-680, 1995 6. Lasjaunias P, Garcia-Monaco R, Rodesch G, et al. Vein of Galen malformation: endovascular management of 43 cases. Child’s Nerv Syst, 1991; 7:360-367 7. Levrier O, Métellus P, Fuentes S, Manera Luis, Dufour H, Grisoli F , Bartoli JM, Girard N. Use of self-expanding stent with balloon angioplasty in the treatment of dural arteriovenous fistulas involving the transverse and/or sigmoid sinus: functional and neuroimaging-based outcome in 10 patients. J Neurosurg, 104: 254-263, 2006 8. Liu JK, Dogan, A, Ellegala DB, Carlson J, Nesbit GM, Barnwell SL, Delashaw JB. The r ole o f s urgery f or h igh-grade i ntracranial d ural a rtriovenous f istulas: Importance of obliteration of venous outflow. J Neurosurg 110: 913-920, 2009 9. Raybaud CA, Strother CM, Hald JK. Aneuryms of the vein of Galen: embryonic considerations and anatomical features relating to the pathogenesis of the malformation. Neuroradiology 1989, 31:109-128, 1989 10. Satomi J, Van Dijk MC, TerBrugge KG, Willinsky RA, Wallace MC. Benign cranial dural arteriovenous fistulas: outcome of conservative management based on natural history of the lesion. J Neurosurg 2002, 97: 767-770 11. Söderman M, Pavic L, Edner G, Holmin S, Andersson T: Natural history of dural arteriovenous shunts. Stroke 39: 1735-1739, 2008 12. Upchurch K, Feng L, Duckwiler GR, Frazee JG, Martin NA, Vinuela F. Nongalenic ateriovenous fistulas: History of treatment and technology. Neurosurg Focus 20(6): E8, 2006 Please See the papers from : Venous Brain Circulation Disorders, Neurosurgical Focus, Vol 27, November, 2009
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CEREBROVASCULAR DISEASE IN CHILDREN. Professor Marianne Juhler Dpt. Of neurosurgery Copenhagen University Hospital, Denmark
Pediatric cerebrovascular disease is considerably different from cerebrovascular disease in adults in almost every aspect - underlying causes, risk factors, clinical presentation and prognosis. Focal syndromes p ertaining to cerebrovascular territories and functional brain anatomy particularly in children > 1 year resemble adult clinical presentations, whereas the clinical picture in very young children is often d ifferent with seizures and general encephalopathy as predominant symptoms. Based on major differences between infants and older children in types and causes of brain vascular disease, it is relevant to further divide vascular disease in children into major categories:
Vascular brain disease in infants is mostly related to intrauterine and perinatal factors and p rematurity. G erminal m atrix i ntraventricular h aemorrhage ( GM-IVH) a nd periventricular leucomalacia (PVL) are the main entities. Brain vascular disease in full term babies is mainly caused by birth injuries. •
GM-IVH. The germinal matrix consists of thin-walled vessels, migrating neuronal components and vessel precursors located in the sub-ependyma of the lateral ventricles. It is transiently present having matured by the 34th gestational week. GM-I VH is most commonly seen in babies 1 500 g r). I ntraventricular a dministration o f streptokinase to obtain lysis of the clots has also been used with the intent to r e-open C SF p athways an d t hereby a void a p ermanent n eed f or hydrocephalus treatment. However, two randomized trials fails to show a more favourable outcome in mortality and shunt dependency following clot lysis compared to conservative treatment.
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•
Intracranial haematomas caused by cranial birth injuries is a differential diagnosis. However, these typically occur in large full-term babies. Assisted delivery by vacuum extractor or forceps increases the risk to approximately 1 % compared to approximately 1 ‰ following vaginal delivery or cesarian section. Subdural haematoma with a tentorial or interhemspheric predilection is the most frequent type of intracranial vascular birth injury. The requirement for neu rosurgical intervention with evacuation of a birth trauma haematoma is much less frequent than the reported incidence.
•
PVL is a white matter disease affecting the periventricular zones, which in prematures i s a w atershed z one b etween d eep a nd s uperficial v essels. Ischemia, i nfection an d p rematurity a re t he m ajor c auses. T he pathophysiology and hence treatment is related to hypoxic-ischemic brain injury.
•
Vein of Galen aneurysm is a rare arteriovenous (AV) malformation in which arterial b lood f rom t he c horoidal a nd/or p osterior c erebral a rteries i s shunted into a dilated vein of Galen. It usually presents in neonates with a characteristic combination of cyanotic heart disease/heart failure, hydrocephalus and seizures. The symptoms are all caused by the high blood flow and large A-V shunt through the malformation, which “steals” a major part of the infant’s cardiac output. Hydrocephalus is due to compression of the aqueduct. If the situation is not resolved quickly, there is a high risk of either mo rtality f rom h eart f ailure o r b rain d amage d ue t o a trophy secondary to “misery perfusion” and ischemia. This vascular malformation may also present in older infants as a parenchymal A VM of the thalamus/midbrain with thalamic feeders draining into the vein of Galen.
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Endovascular embolization as single or serial procedures depending on the complexity of the vascular architecture is considered the treatment of choice and dramatically improves outcome. Vascular brain disease in children > 1 yearis divided into haemorrhagic and ischemic types. Whereas the causes for haemorrhagic and ischemic stroke in adults are frequently similar with atherosclerosis and hypertension as leading risk factors, there are very distinct differences between these two types of vascular disease in pediatric patients. In adults, ischemic stroke is more common than haemorrha ge, but haemorrhage accounts for half of the cases in pediatric cerebrovascular disease. Any type of stroke in the pediatric age group is rare (approx. 3/100.000). •
Non-traumatic intracranial haemorrhage in children > 1 year presents as intraparenchymal bleeding (ICH) or as subarachnoid haemorrhage (SAH). The majority are children > 10 years. Male/female ratio is 3:2. Most often the underlying cause is a structural vascular disorder such as A VM, aneurysm or vasculitis/moya-moya, but haematologic/coagulation disorders may also give rise to intracranial haemorrhage. The distribution in round figures and types of bleeding are shown in the table below:
Symptoms are raised intracranial pressure, reduced level of consciousness and focal deficits. Neurosurgical treatment is directed at the cause and at reducing intracranial pressure. Applied neurosurgical procedures are thus evacuation of IVH, obliteration of AVM, clipping of aneurysms and control of associated hydrocephalus. AVM obliteration may be obtained by surgical excision, embolisation, radiuosurgery or a combination of these treatment modalities. The outcome from any ca use of haemorrhage in the brain depends on the severity of bleeding and rapid access to acute neurosurgical treatment. •
Ischemic s troke i n c hildren comprises v ery h eterogeneous d iagnoses. Symptoms a re t ypically f ocal n eurological d eficits, w hich c an a ppear suddenly as TIA or stroke, but less typical presentations with seizures and headache are also seen. The cause can be structural vascular abnormalities or metabolic/haematologic disorders. The numerous underlying causes are vastly influenced by geographic and ethnic/genetic factors. •
Sickle cell disease, genetic coagulation disorders, other in-born errors of metabolism and heart valve disease are all relevant risk factors for cerebral thrombosis or embolism.
•
Stenosis of intracranial arteries can affect either a single or multiple 91
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vessels. If the stenosis affects a single intracranial artery, it is usually caused by infection or post-infectious vasculitis. •
If structural stenosis progresses to bilateral occlusion of ICA and its branching into ACA and MCA, a network of fine collaterals develops, which is known as “moya-moya” (Japanese for “small cloud”) because of its angiographic appearance. Moya-moya is mainly a vascular disease in the Asian population; but it also occurs in non-Asians either as a a s a c omplication t o o ther d iseases ( e.g. d ifferent m etabolic disorders, intracranial tumors, radiation induced vasculitis) or with no demonstrable cause.
•
In obese children a metabolic syndrome has been described with high blood l ipids, h yperinsulineamia a nd i ncreased r isk o f e arly atherosclerosis.
•
Arterial di ssection i nvolves t he m ajor n eck a rteries a nd l eads to trombosis and occlusion causing brain ischemia and infarction in the vascular territory supplied by the affected artery. Half of the cases are traumatic – including both major trauma and trivial falls . The ot her half of the cases is evenly distributed into connective tissue disease, congenital anatomical anomaly of the cervical spine and unknown causes.
Revascularization surgery as opposed to conservative/medical treatment with anti platelet agents or anticoagulants is more readily considered in pediatric stroke patients than in adults – either as “direct” anastomosis (ECIC bypass) or as “indirect” pial synangiosis of extracranial vessels widely to the cortical surface. Decompression craniectomy for large MCA infarcts with ischemic edema, mass effect and raised intracranial pressure probably improves survival and possibly also functional prognosis. Thrombolysis similar to acute stroke treatment in adults may be beneficial, but the experience is very limited.
References 1. Imperial College of L ondon. Neonatal Imaging. http://www1.imperial.ac.uk/medicine/about/divisions/cs/imagesci/pedmr_0/ 2. Beek E, Groenedal F. Neonatal brain US. http://www.radiologyassistant.nl/en/440c93be7456f 3. Yu B, Li S, Lin Z, Zhang N. T reatment of posthemorrhagic hydrocephalus in premature i nfants w ith s ubcutaneous r eservoir d rainage. P ediatric Neurosurgery 2008;45:119-125. 4. Intraventricular s treptokinase a fter i ntraventricular h emorrage i n n ewborn infants. Cochrane Database Syst Rev 2007;17(4):CD000498. 92
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5. Lasjaunias PL, Chng SM, Sachet M, Alvarez H, Rodesch G, Garcia-Monaco R. The management of vein of Galen aneurysmal malformations. Neurosurgery. 2006 Nov;59(5 Suppl 3):S184-94. 6. Kumar R, Shukla D, Mahapatra AK. Spontaneous intracranial hemorrhage in children. Pediatric Neurosurgery 2009;45:37-45 7. Sproule DM, Kaufman P. Mitochondrial encephalopathy, lactic acidosis and stroke-like e pisodes: b asic c oncepts, c linical p henotype a nd t herapeutic management of the MELAS syndrome. Ann NY Acad Sci 2008;1142:133-158. 8. Scott RM, Smith JL, Robertson RL, Madsen JR, Soriano SG, Rockoff MA. Longterm outcome in children with moya-moya syndrome after cranial revascularization by pial synangiosis. J Neurosurg (Pediatrics) 2004;100:142149. 9. Guzman R , L ee M , Ac hroi A , B ell-Stephens T, K elly M , D o H M, M arks M P, Steinberg G K. C linicla o utcome a fter 45 0 r evascularization p rocedures f or moya-moya disease. 10. Hasan I, Wapnick S, Tenner MS, Couldwell WT. Vertebral artery dissection in children: a comprehensive review. Pediatric neurosurgery 2002;37:168-177. 11. Arnold M, Steinlin M, Baumann A, Nedelchev K, Remonda L, Moser SJ, Mono ML, Schroth G , Mattle HP, B aumgarthner RW. Thrombolysis in c hildhood stroke: report of 2 cases and review of the literature. Stroke 2009;40(3):801 807. 12. Liu YL, Liang HR, Liu HT , Li SY, Zhou YY, Cheng HL, Zhou LS. Association of serum adiponectin levels with artherosclerosis and the metabolic syndrome in obese children. J Pediatr Endocrinol Metab. 2010 Aug;23(8):743-51. 13. Khullar D, Andeejani AM, Bulsara KR. Evolution of treatment options for vein of Galen malformations. J Neurosurg Pediatr. 2010 Nov;6(5):444-51. 14. Skjøth-Rasmussen J, Roed H, Ohlhues L, Jespersen B, Juhler M. Complications following L inac s tereotactic r adiation fo r c erebral a rteriovenous malformations. Int J Radiat Oncol Biol Phys. 2010 Jun 1;77(2):542-7 15. Mirza B, Mønsted A, Harding J, Ohlhues L, Roed H, Juhler M. Stereotactic radiotherapy and radiosurgery in pediatric patients: analysis of indications and outcome. Childs Nerv Syst. 2010 Dec;26(12):1785-93
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CAVERNOMAS – HELSINKI SERIES WITH A SPECIAL EMPHASIS ON ‘UNCOMMON’ LESIONS IN THE BRAIN AND SPINE Mika Niemelä MD PhD, Juri Kivelev MD PhD, Riku Kivisaari MD PhD, Aki Laakso MD PhD, Martin Lehecka MD PhD, Göran Blomstedt MD PhD, Reza Dashti MD PhD, *Reina Roivainen MD PhD and Juha Hernesniemi MD PhD Departments of Neurosurgery and Neurology*, Helsinki University Hospital
Literature review Cavernous malformations, or cavernomas, of the CNS are relatively common in the population with prevalence as high as 0.5% detected usually between the second and f ifth d ecade o f l ife [ 1-3]. F amilial f orms ( autosomal-dominant p attern o f inheritance with incomplete penetrance) are more frequent in Hispanic-Americans, account-ing for up to 50% of cavernomas [4]. Among Caucasians, the familial forms are enc ountered in only 10-20% of patients [4, 5]. P atients with family history typically have multiple cavernomas, whereas sporadic forms mostly present with a single lesion. Three genes responsible for development of the cavernomas have been identified [6-9]. When their mutations express, loss of respective proteins l eads to formation of the lesion, with dilated thin-walled sinusoids or caverns covered by a single layer of endothelium that has undeveloped interstitial junctions and subendothelial interstitium [10, 11]. Blood flow inside the sinusoids is low , predisposing to intraluminal sta-sis and thrombosis. Due to fragility of the sinusoid wall, a cavernoma causes repetitive microhemorrhages into the surrounding neural tissue with formation of perifocal hemosiderosis and reactive gliosis. Such local homeo-static instability produced by either genetic or reactive environmental factors (inflammation, breakdown of the blood-brain barrier, gliosis) may provoke intensive neoangiogenesis and proliferation of the sinusoids. Subse-quently, lesions enlarge and grow, which may coexist with clinical progression. The na tural h istory o f b rain c avernomas i s r elatively b enign a nd u p t o 2 1% o f patients are asymptomatic [12]. The most frequent manifestations are seizures, focal neurological deficits and h emorrhage. Seizure activity o c-curs in up to 80% of patients with supratentorial cavernomas most probably being evoked by perilesional in-traparenchymal changes [2, 13-16]. Focal neurological deficits are typical for cavernomas located close to elo-quent regions of the brain and for spinal lesions. Headaches are fairly common complaint. An acute exacerbation of the symptoms of any clinical pattern of cavernomas is prevalently r elated t o h emor-rhage t he r isk b eing 0 .1-5% p er p atient-year a nd depending on the l ocation of the cavernoma increasing typically in deeper lesions of the brain [2, 3, 14, 17, 18] . Bleedings are usually not life-threatening, but, may be a ble t o c ause d evastating n eurological d eficits. F urthermore, t he r isk o f r ebleeding i ncreases f rom 5% t o 6 0% p er p a-tient y ear [ 18-21] i ndicating a ctive treatment of the lesion in early stages after the first event. Microsurgical removal of the symptomatic cavernoma is the most effective method.
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Most operated patients with a lesion in a safely accessible location usually gain convincing relief of their symptoms. Nevertheless, deep or eloquent sites of the brain and intramedullary spine location increase surgical invasiveness and risks of postoperative complications [22, 23].
Objective After t he a dvent o f M RI i n c linical p ractice, t he n umber o f p atients i ncreased markedly, allowing the main clini-cal features and results of surgical treatment to be determined. Due to their rareness intraventricular, multiple, and spinal cavernomas as well as temporal ones with epilepsy were rather poorly described in the literature.
Recent clinical and research developments – Helsinki series of ‘uncommon lesions’ Data on 383 consecutive patients with a total of 1101 brain and spinal cavernomas treated at Helsinki University Hospital (catchment area 1.8 million) from January 1, 1980 to December, 12 2009 were retrospectively analyzed. T welve patients (3.1%) had i ntraventricular c avernomas, 4 4 p atients ( 11.5%) m ultiple c avernomas, 1 4 patients (4 %) s pinal c avernomas, a nd 5 3 p atients ( 15.1%) t emporal l obe cavernomas. Results of their treatment were as-sessed at a median of two, eight, three, and six years, respectively. I Inraventricular cavernomas (n=12) The median age of our patients on admission was 47 ye ars (range 15 – 66 yrs). As a presenting symptom, 11 patients (92%) had an acute mild to severe headache accompanied by nausea and vomiting. Three patients (27%) with a cavernoma in the fourth ventricle had cranial nerve deficits (paresis of the III, VI, and VII nerves, separately o r i n v arious co mbinations). F our p atients ( 36%) h ad h ydrocephalus o n admission, but shunting was neces-sary in only one patient. Eight patients (67%) experienced extralesional hemorrhage confirmed by CT and lumber puncture. The rebleeding rate was 89% per patient-year. Six of the 12 IVCs were located in the lateral ventricle, mainly on the left side. One IVC was in the third ventricle, without radiological signs of enlarged ventricles. In five patients (45%), IVC was found in the fourth ventricle, typically in 10 the medial part of the floor. Nine pa-tients underwent surgical excision of the IVC to prevent rebleedings or to eliminate the mass-effect, or both. Five of the nine patients operated on were symptom-free at follow-up. Age, sex, and previous bleeding had no influ-ence on outcome. No mortalities occurred. Patients with fourth ventricle cavernomas had a worse outcome than those with lateral-ventricle lesions. II Multiple cavernomas (n=44) Mean age at diagnosis was 43.6 years (range 4-69 yrs) and 36.3 years (range 0.6-
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71 yrs) for men and women, respectively. Nineteen patients (43.2%) had a history of one or more symptomatic extralesional hemorrhages. Altogether , 18 patients (40.9%) h ad a n e pileptic d isorder, a nd i n s ix o f t hem ( 33.3%) a n i ntracerebral hemorrhage from the cavernoma was present on admission. A total of 762 cavernoma was found in these 44 patients. The median number of lesions per patient was six and the largest lesion 50mm in diameter . Microsurgery was per formed on 30 patients (68.2%), and a total of 34 cavernomas were removed. In the majority of cases, the removed cavernoma was the largest lesion, and usually with signs of recent bleeding. No patients were lost to follow-up and no deaths occurred. Thirty-four patients (77.2%) had no disability (GOS V), nine (20.5%) had moderate dis-ability (GOS IV), and one (2.3%) had severe disability (GOS III). During the followup f our pa tients s uffered fr om a C T-verified I CH. B leedings o ccurred o nly in conservatively treated patients. MRI was performed during follow-up on 22 patients. Altogether, 54 de novo lesions were found. III Spinal cavernomas (n=14) The median age at presentation was 45 years (range 20-57 yrs). In nine patients (63%), t he c avernomas w ere i ntramedullary, w hile f our p atients ( 29%) h ad a n extradural lesion and one had an intradural extramedullary cav-ernoma with an isolated intramedullary hemorrhage. P atients suffered from sensorimotor paresis, radicular pain, or neurogeni c micturition disorders in different combinations or separately. Three patients (21%) presented with acute onset of symptoms and rapid neurological d ecline ne cessitating e mergency s urgical t reatment. H emorrhage occurred in s even p atients ( 50%) b efore s urgery. I ndications f or m icrosurgical removal of a spinal cavernoma we re progressive neurological deteriorati on in 12 patients (86%) and prevention of bleeding and consequent neu-rological decline in the remaining two pat ients (14%). Nine patients (64%) underwent a hemilaminectomy and five (36%) a laminectomy . At discharge, ten patients (71%) experienced improvement of their neurological status, three patients (21%) had worsening of the symptoms or some new deficits , and one patient r emained the same. At the last follow-up, eight patients (57%) experienced further improvement of t heir s ymptoms. O ne p a-tient ( 7%) w as w orse t han p reoperatively. A n extramedullary location proved to be better and safer regarding outcome: four of these five patients (80%) demonstrated further improvement of the symptoms, whereas only four of eight (50%) with an intramedullary lesion did the same. IV Temporal lobe cavernomas (n=53) The median age of patients at radiological diagnosis was 37 years (range 7-64 yrs). Epileptic seizure was the most frequent symptom occurring in 40 patients (82%). Before surgery, nine patients ( 18%) had a CT -confirmed hemorr hage. Altogether , 12 bleedings o ccurred. F orty-nine p atients w ere o perated o n. L esionec-tomy w as performed on 38 of 40 patients (95%) presenting with seizures. All ten patients with only one seizure preoperatively, were seizure-free at follow-up. Of 16 patients who
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had experienced between two and five seizures preoperatively , 11(69%) were seizure-free, and of 13 patients with numerous seizures preoperatively, nine (69%) were seizure-free. Neither type, duration of seizures, nor location of the cavernoma inside the temporal lobe cor-related with postoperative seizure outcome. At followup, nine patients (18% ) had a new or worsened neurologi-cal deficit. Memory disorder was present in five patients with a history of epilepsy , but four of these patients already had this problem preoperatively. None of the asymptomatic patients developed neurological deficits post-operatively.
Conclusions Microsurgical treatment of brain and spine cavernomas is safe and effective. Most operated p atients w ith i ntra-ventricular, m ultiple, s pinal, a nd t emporal l obe cavernomas had significant improvement of their symptoms. Due to rareness of these lesions, a decision to operate may be difficult requiring vast experience and dexterity of the neurosurgeon. In patients with cavernomas of the fourth ventricle, surgical r isks a re h igher t han w ith c avernomas o f o ther v entricles. I n c ases o f multiple cavernomas, removal of epileptogenic cavernomas is beneficial but antiepileptic d rugs a re u sed d ue t o t he r emaining l esions. S pinal i ntramedullary cavernomas carry higher risks of permanent neurological deficits than those in extramedullary location. In these patients, the worst prognosi s was linked to bl adder disorders, which occurr ed in 43% of patients despite surgical treatment. In cases of tempo-ral lobe cavernoma, favorable seizure-outcome after lesionectomy is expected. Duration of epilepsy did not c orre-late w ith s eizure p rognosis. T he m ost f requent d isabling s ymptom a t follow-up was memory disorder, considered to be the result of a complex interplay between chronic epilepsy and possible damage to the temporal lobe during surgery .
Key references 1. Cohen DS, Zubay GP, Goodman RR: Seizure outcome after lesionectomy for cavernous malformations. J Neurosurg 83:237-242, 1995 2. Robinson JR, Awad IA , Little JR: Natural history of the cavernous angioma. J Neurosurg 75:709-714, 1991 3. Zabramski J M, Wascher T M, S petzler R F, J ohnson B , G olfinos J , D rayer B P, Brown B, Rigamonti D, B rown G: The nat ural history of familial cavernous malformations: results of an ongoing study. J Neurosurg 80:422-432, 1994 4. Rigamonti D, Hadley MN, Drayer BP, Johnson PC, Hoenig-Rigamonti K, Knight JT, Spetzler RF : Cerebral c avernous malformations. Incidence and familial occurrence. N Engl J Med 319:343-347, 1988 5. Russel DS, Rubenstein LJ: Pathology of tumors of the nervous system, in
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Baltimore, Williams & Wilkins, 1989 6. Craig HD, Gunel M, Cepeda O, Johnson EW, Ptacek L, Steinberg GK, Ogilvy CS, Berg MJ, Crawford SC, Scott RM, Steichen-Gersdorf E, Sabroe R, Kennedy CT, Mettler G, Beis MJ, Fryer A, Awad IA, Lifton RP: Multilocus linkage identifies two new loci for a mendelian form of stroke, cerebral cavernous malformation, at 7p15-13 and 3q25.2-27. Hum Mol Genet 7:1851-1858, 1998 7. Dubovsky J, Zabramski JM, Kurth J, Spetzler RF, Rich SS, Orr HT, Weber JL: A gene r esponsible f or c avernous m alformations o f t he b rain m aps t o chromosome 7q. Hum Mol Genet 4:453-458, 1995 8. Hayman LA, Evans RA, Ferrell RE, Fahr LM, Ostrow P, Riccardi VM: Familial cavernous angiomas: natural history and genetic study over a 5-year period. Am J Med Genet 11:147-160, 1982 9. Labauge P, L aberge S , B runereau L , L evy C , Tournier-Lasserve E : H ereditary cerebral c avernous a ngiomas: c linical a nd g enetic f eatures i n 5 7 F rench families. Societe Francaise de Neurochirurgie. Lancet 352:1892-1897, 1998 10.McCormick WF,Nofzinger JD: "Cryptic" vascular malformations of the central nervous system. J Neurosurg 24:865-875, 1966 11.Wong J H, A wad I A, K im JH : U ltrastructural p athological f eatures of cerebrovascular malformations: a preliminary report. Neurosurgery 46:14541459, 2000 12. Hsu FP, Rigamonti D, Huhn SL: Epidemiology of Cavernous Malformations, in Awad I , B arrow D L ( eds): C avernous M alformations. P ark R idge, i llinois, American association of Neurological Surgeons, 1993, pp 18 13. Awad IA, Robinson JR: Cavernous Malformations and Epilepsy , in Awad IA , Barrow DL ( eds): C avernous M alformation. p ark R idge, I llinois, A merican Association of Neurological Surgeons, 1993 14. Del Curling O ,Jr, Kelly DL,Jr, Elster AD, Craven TE: An analysis of the natural history of cavernous angiomas. J Neurosurg 75:702-708, 1991 15. Paolini S, Morace R, Di Gennaro G, Picardi A, Grammaldo LG, Meldolesi GN, Quarato PP, Raco A, Espo-sito V: Drug-resistant temporal lobe epilepsy due to cavernous malformations. Neurosurg F ocus 21:e8, 2006 256. Robinson JR, Awad IA , Little JR: Natural history of the cavernous angioma. J Neurosurg 75:709-714, 1991 16. Steiger HJ, Markwalder TM, Reulen HJ: Clinicopathological relations of cerebral cavernous angiomas: observations in eleven cases. Neurosurgery 21:879-884, 1987 17. Kondziolka D, Lunsford LD, Kestle JR: The natural history of cerebral cavernous malformations. J Neuro-surg 83:820-824, 1995
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18. Porter P J, W illinsky R A, Ha rper W , W allace M C: C erebral c avernous malformations: natural history and prognosis after clinical deterioration with or without hemorrhage. J Neurosurg 87:190-197, 1997 19. Ferroli P, C asazza M , M arras C , M endola C , Franzini A , B roggi G : C erebral cavernomas and seizures: a retrospective study on 163 patients who underwent pure lesionectomy. Neurol Sci 26:390-394, 2006 20. Fritschi JA, Reulen HJ, Spetzler RF, Zabramski JM: Cavernous malformations of the brain stem. A review of 139 cases. Acta Neurochir (Wien) 130:35-46, 1994 21. Wang CC, Liu A, Zhang JT, Sun B, Zhao YL: Surgical management of brain-stem cavernous malformations: report of 137 c ases. Surg Neurol 59:444-54; discussion 454, 2003 22. Garrett M, Spetzler RF : Surgical treatment of brainstem cavernous malformations. Surg Neurol 72 Suppl 2:3-9, 2009 23. Abla AA, Lekovic GP, Garrett M, Wilson DA, Nakaji P, Bristol R, Spetzler RF. Cavernous malformations of mthe brainstem presenting in childhood: surgical experience in 40 patients. Neurosurgery 67:1589-98, 2010
Doctoral thesis by Juri Kivelev, Dec 10, 2010, Helsinki Neurosurgery I
Kivelev J*, Niemelä M, Kivis aari R, Hernesniemi J: Intraventricular c erebral cavernomas: a series of 12 patients and review of the literature. J Neurosurg 112(1):140-9; 2010
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Kivelev J*, Niemelä M, Kivisaari R, Dashti R, Laakso A, Hernesniemi J: Longterm outcome of patients with multiple cerebral cavernous malformations. Neurosurgery 65:450-5, 2009
III K
ivelev J*, Niemelä M, Hernesniemi J: Outcome after microsurgery in 14 patients with spinal cavernomas and literature review. J Neurosurg Spine 13(4):524-534, 2010
IV
Kivelev J*, Niemelä M, Blomstedt G, Roivainen R, Lehecka M, Hernesniemi J: Microsurgical treatment of temporal lobe cavernomas. Acta Neurochir (Wien), epub Sep 26, 2010
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EXTRA- AND INTRACRANIAL DISSECTIONS Jannick Brennum, M.D., Dr.Med., MHM University Clinic of Neurosurgery, Rigshospitalet, Copenhagen, Denmark
Objective The objective is to give a brief overview of spontaneous and blunt traumatic extraand intra¬cranial vascular dissections, in the following just referred to as dissections.
Introduction The division of dissections into spontaneous and traumatic, may rightly be thought of as overlapping, since a precipitating trivial trauma is reported in approximately a quarter of all spontaneous dissections. Blunt traumatic dissections are defined as a cerebrovascular structural defect that is directly attributable to a known high-energy non-penetrating injury.
Epidemiology The annual incidence of spontaneous dissections is currently quoted around 3-5 cases/ 100.000 persons . Spontaneous dis sections is the cause of 0.5-2% of all ischemic strokes, but they cause of up to 20% of all ischemic strokes in patients younger than 50 y ears of age. The male / female ration is 1, but spontaneous dissections occur earlier in women, in average 5 y ears earlier. The incidence of dissection following blunt trauma is less certain, but recent data suggest that it occurs in around 1%. Traumatic dissections of the carotid are approximately twice as common as dissections of the vertebral artery. Motor vehicle accidents are by far the most common cause. In patients with traumatic dissection the mortality rate is approximately 10% and the rate of cerebral strokes 25-50%.
Mechanism Some of the mechanisms are basically the same, whether the dissection is spontaneous o r t raumatic. T he s pontaneous d issections a re i nitiated w ith defect/lesion in the intima, which the blood flow rips up, creating an intima flap. The bloodstream d issects i nside t his i ntima f lap ( subintimal di ssection) o r m ight penetrate t he m uscular me dia l ayer o f t he v essel w all c reating a s ubadventitial dissection. The latter often causing a dissection aneurysm and if it is intracranial may cause a SAH. The bulging of the vessel wall by the dissection might in itself cause occlusion of the vessel, which in turn may lead to cerebral ischemia. But the cause of cerebral ischemic stroke following dissection is more commonly embolism. The reason for this is, that as soon at the tear in the intima has been created and the dissection occurs, the bloodstream is exposed to the intrinsic clotting factors, which
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leads to quick formation of a thrombus in the vessel lumen, the source of emboli. In traumatic dissections it is in many cases a flexion/extension force in combination with rotational forces that stresses the vessel wall or compresses the vessel against bony structures (anterior spinal column, the styloid process, foramen transversarium fractures, skull base fractures). In traumatic dissections more than one cervical artery is affected in approximately 25% of the cases.
Disposing factors A n umber o f d isposing f actors a re r eported i n s pontaneous di ssections, m any relating to abnormalities in the connecting tissue (Ehlers-Danlos syndrome type IV, Marfan syndrome, cystic medial necrosis, polycystic kidney disease etc.). However, such connective tissue disease is found in less than 5% of patients presenting with spontaneous dissections. There is some degree of genetic disposition, and those with a family history of dissection, do have an increased risk of repeated dissections. The majority of spontaneous dissections are seen in the autumn, which have given rise to a speculation of possible infectious cause of some spontaneous dissection. There are factors in trauma patientsthat increase the risk of dissection (cervical spine fractures, unexplained neurological deficits, basilar fracture into the carotid canal, Le fort II & II fractures, neck soft tissue injury , Horner’s syndrome, ischemic stroke, GCS < 6, hanging with anoxic injury).
Symptoms The c lassical t riad o f s ymptoms i n d issection i s a cute n eck o r h ead, H orner’s syndrome and cerebral ischemic symptoms. It is very common that not all symptoms are present.
Diagnosis The diagnostic ”gold standard” is DSA. However, DSA has commonly been replaced
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by CTA as the primary diagnostic tool. CTA have been demonstrated to deliver a high degree of sensitivity and specificity with modern multi-slice scanners. MRI is inferior to CT A as a diagno stic tool in dissection, but superior in recognition of cerebral ischemia.
Treatment The ev idence b ase f or t reatment p er s e, a nd f or t he c hoice o f t reatment i n extracranial spontaneous and traumatic vascular dissection is weak. The evidence base for treatment of intracranial vascular dissection is better , because the risk of recurrent SAH is very high, and the mortality seems to be reduced substantially by treatment. In general treatments of dissection can be divided into conservative, medical and surgical/endovascular. In spontaneous dissection the general practice is antithrombotic therapy, either with initial intravenous heparin and then warfarine or antiplatelet agents (aspirin +/other a gents). T here i s cu rrently n ot s ubstantial e vidence s uggesting t hat o ne treatment regime is better than the other . Small series of thrombolytic treatment and endovascular therapy has been reported. The extracranial aneurysms related to dissection do not seem to be a cause for major concern, the majority seem to be stable, some reduce in size, and rupture is an extraordinary occurrence. Regarding the intracranial vascular dissection the risk of recurrent haemorrhage is high and active treatment is indicated. This is most commonly undertaken by endovascular stent placement with or without simultaneous coil placement, the most common other options at proximal vessel oc clusion, either endovascular or surgical. T he proximal vessel occlusion may in some cases be supplemented with bypass surgery.
Prognosis Following spontaneous dissections the overall neurological outcome is good or excellent in 70-80% of cases, and the mortality rate is approximately 5%. The rate of subsequent cerebral ischemic events is reported varying from 0.3-3.4%/year, the risk is greatest in the first months after the diagnosis. Radiologically most healing of dissection occurs in the first 6 months.
Conclusion The diagnosis and treatment of extra- and intracranial vascular dissections has increased dramatically in the past few decennia. The increased diagnosis is no doubt related to the improved diagnostic techniques, especially CTA. This is to some extend also true for the rapid increase of treatments, however , we are still short on solid evidence regarding the benefits of most of the treatments.
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References Fusco MR, Harridan MR. Cerebrovascular dissections – A review part I: Spontaneous dissections. Neurosurgery 2011;68:242-57. Fusco M R, Harrigan M R. C erebrovascular d issections – A r eview p art I I: B lunt cerebrovascular injury. Neurosurgery 2011;
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WHAT YOU SEE IS WHAT YOU GET Helma Westerhof As they leave your office, your patient’s emotional state is more strongly related to your communication skills than to your medical skills. Understanding how to support the content of your medical message with congruent body language, to create an open and friendly atmosphere in your office, and to develop the skills for reading and understanding the non-verbal signs of the patient, is the key to a good doctor-patient relationship. The non-verbal communication channel is more honest and immediate than words. Before you manage to express in words the results of a test, a patient has read it right from your face. And if the content of your message conflicts with your facial expressions and other body-language, the patient will rely on the body-language part. Strong non-verbal communication skills not only support the effective transfer of information, but will also make you work more efficiently , as when p atients feel known and understood, the consultation needs fewer words. This l ecture w ill c over a ll p ractical a nd d irectly s uitable s igns o f non-verbal communication. From the moment of meeting a patient in the waiting room and shaking hands, through seeing them out, the way you sit, the arrangement of your desk and seats, and even your clothing, are important non-verbal signs.
Helma Westerhof (drs.) in brief: Helma Westerhof started her career as a physical-therapist. After her PhD in language and communication and Public Relations she started her own consulting-busines s PQ Consult. PQ Consult specializes in training and consulting on non-verbal communicatio n, medical communication and pa tientcentered communication and practice-design. (www.pqconsult.nl)
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Unspoken messages Non-verbal tools for more effective and pleasant communication
Literature Books: Ekman, P aul: Emotions revealed – recognizing faces and feelings to improve communication and emotional live (Times Books, New York, 2003) Garner, Alan: Conversationally speaking (McGraw-Hill, New York, 1980) Hall, Edward: The Hidden Dimension (Double Day & Co, New York, 1959)
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Mehrabian, Albert: Silent Messages (W adsworth, Belmont, Californi a, 1971) / Nonverbal Communication (Transaction Publishers, New Brunswick, 2007) Pease, Alan & Barbara: The Definitive Book of Body Language (Orion Books, London, 2004) Wassmer, Arthur: Making Contact, Guide to overcoming shyness(Dial, New Y ork, 1978)
Articles Lill, Marianne & Wilkinson, Tim :‘Judging a book by its cover’ - descriptive survey of patient’s preferences for doctors’ appearance and mode of address BMJ 2005; 331: 1524 – 1527 Koster, Rick & Westerhof, Helma: ‘Ruis in de communicatie’ Medisch Contact, 8 april 2005: 572 - 574
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INTRAOPERATIVE NEUROPHYSIOLOGICAL MONITORING IN VASCULAR NEUROSURGERY Francesco Sala, Francesco Cozzi Dept. of Neurosurgery, University Hospital, Verona, Italy
Objective To summarize the evolution of Intraoperative Neurophysiological Monitoring (INM) in vascular neurosurgery over the last decade (2000-2010).
Introduction INM has emerged as one of the path we can take to make progress in Neurosurgery . INM includes both mapping (the functional identification of ambiguous nervous tissue) and monitoring (the continuous assessment of the functional integrity of a neural pathway) techniques. Unlikely from tumour surgery, mapping techniques are rarely if ever needed in vascular neurosurgery . Monitoring techniques, vice-versa, can be used and provide valuable information. Monitoring of somatosensory evoked potentials (SEPs) has been used since the eighties (2,17,18) in aneurysm surgery . Other authors have used a combined SEP - Brainstem auditory evoked potentials (BAERs) protocol (1,7), while motor evoked potentials (MEPs) were introduced more recently (10,11,13,19,20,21). MEPs are generally more suitable to monitor subcortical areas while SEPs are more sensitive to ischemic derangements at the cortical level. In one series (3), SEP monitoring missed intrao perative stroke in 4 out of 7 patients; these were all subcortical strokes due to injury to perforating vessels. From a methodological standpoint it should be kept in mind that evoked potentials recording should be tailored to aneurysm location. For example an anterior communicating artery, anterior cerebral artery or basilar artery aneurysm would be better monitored using a bilateral tibial nerve SEP s and bilateral MEP recordings, while for middle cerebral artery (MCA) aneurysms, controlateral recordings may suffice.
Modern literature review and recent clinical developments In t he p ast d ecade, t he i nterest a round t he u se of I NM i n c erebrovascular neurosurgery has focused on the use of motor evoked potentials. Intracranial aneurysm surgery Neuloh et al. (10) investigated the efficiency of MEP s in comparison to SEP s and microvascular doppler ultrasonography (MDU) in aneurysm surgery. The conclusion of t his s tudy w as t hat M DU a nd e voked p otentials p rovide c omplementary
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information. Yet, MEP monitoring turned out to be superior to SEP s and MDU in detecting motor impairment due to inadequate temporary clipping, inadequate retraction, vasospasm or compromise to perforating vessels, and had the highest impact on the surgical strategy. MDU was superior to evoked potentials in detecting inadvertent vessel occlusion, although could not detect collateral flow. It should also be n oted t hat M DU e valuates l ocal f low a t s pecific t imes, w hile S EP a nd M EP monitoring provide a continuous functional information. Quinones-Hinojosa et al . ( 13) u sed M EP a nd S EP m onitoring a fter t ranscranial electrical stimulation (TES) to monitor 30 patients with basilar artery aneurysms. They observed INM changes in 10 patients, with MEP changes being, in general, more evident and occurring earlier than SEP changes. They concluded that MEP monitoring is more sensitive than SEP m onitoring in detecting brainstem ischemia due to derangements in the basilar or perforating arteries. Horiuchi et al. (4) i nvestigated the value of MEP monitor ing to detect blood flow insufficiency in cortical branches of the middle cerebral artery (MCA) during surgery for MCA aneurysms. In 43 out of 53 patients with unchanged MEPs and SEPs the neurological outcome was favourable. Viceversa, 9 presented MEP changes but in 5 of these SEP remained stable, suggesting that SEPs are not reliable to detect blood flow insufficiency in the MCA and lenticulostriate artery territories. Szelenyi et al. (21) looked at correlations between intraoperative MEP changes and motor outcome. Significant MEP changes (>50% drop in amplitude and/or > 20 mA increase in threshold) occurred in 14 (12%) of 116 patients during temporary clipping ( 64%), p ermanent c lipping ( 29%) hy potension ( 14%) o r r etractor misplacement (7%). In those 14 patients, motor outcome was normal in 4 (29%), not assessable in 3 (21%), transiently impaired in 1 and permanently impaired in 6 (50%) patients. ME P c hanges w ere i rreversible i n 3 p atients. Pr eserved M EPs a lways correlated with good motor outcome; MEP loss always correlated with severe motor deficits. The issue of recording MEP after either TES or direct cortical stimulation (DCS) has been addressed in another paper by Szeleny i et al. (20). While one method can compensate for the drawbacks of the other, no conclusion has been reached whether one is better than the other or a combination of the two warrant the best clinical results. Intracranial AVM surgery There are very few reports on the use of INM during surgery for brain arteriovenous malformations (AVMs) in the literature. Very recently, Ichikawa et al. (5) presented a study on MEP monitoring in 21 patients with cerebral AVMs. In 16 patients MEP were used to detect blood flow insufficiency to the corticospinal tract. Four patients presented MEP changes, which were reversible in three; non of these three patients experienced long-lasting motor impairment. In 17 patients MEP were monitored to prevent a direct injury to motor tracts and only one patient had a transient drop in MEP amplitude. None of these patients developed motor weakness. Therefore, MEP 108
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monitoring substantially contributed to preventing postoperative motor paresis in patients undergoing cerebral AVM surgery. Endovascular treatment for brain and spinal AVM A few authors have evaluated the benefit of INM during endovascular procedures for either aneurysm or AVMs. Liu e t al .(6) a nalyzed t he e fficacy o f I NM in d etecting i schemic c hanges d uring endovascular treatments for cerebral aneurysms. They analyzed 35 patients who underwent 50 endovascular procedures including balloon test occlusion (n=19), GDC coil embolization (n=22) or permanent vessel occlusion (n=9). INM included EEG and/or SEPs and/or BAERs depending on the aneurysm location. Significant changes in I NM w ere s een i n 2 6% ( n=9) o f t he p atients a nd a ltered t he management in 14% (n=5); none of these experi enced permanent neurological deficits. In another 11% (n=4) of the patients the management could not be altered by INM changes due to aneurysm rupture or severe vasospasm. Niimi et al . ( 12) a nd S ala e t a l. ( 15) h ave c ombined I NM a nd p harmacological provocative tests during the embolization of spinal cord and brain AVMs. It is well known that the int ra-arterial injection of embolizing materials into the cerebral or spinal circulation exposes to the risk of ischemic complications due to vasospasm or unrecognised/undesirable obliteration of vessels feeding the normal brain or spinal cord. Nowadays, endovascular procedures for complex vascular malformations can last several hours. To avoid discomfort to the patient and to control his breathing in order to obtain high-resolution images during the procedure, general anesthesia is increasingly used. Under general anesthesia, unless a wake-up test is performed, the only way to assess the functional integrity of sensory and motor pathways is to perfom INM. The goal of INM is to warn the neuroradiologist of an impending injury to these long tracts so that action can be taken in time to restore adequate perfusion and avoid irreversible nerurological deficits. In summary , once the catheter is in the emb olizing position, and before any embolizing material is injected, provocative testing for neuronal functi on is performed with an intra-arterial injection of a short acting barbiturate followed by the injection of lidocaine. Barbiturates block neuronal activity, while lidocaine blocks axonal conduction. Accordingly , a positive provocative test (i.e. more than 50% decrease in SEP amplitude and /or mMEP dis appearance) indicates that the vessel distal to the tip of the microcatheter supplies the functional gray or white matter of the b rain or s pinal c ord. P rovocative t ests e ssentially m imic t he e ffect o f t he embolization. Whenever a provocative test is positive, embolization is not performed from that specific catheter position but either a superselective catheterization or approaching the AVM from a different feeder are attempted. If the test is negative (no INM changes) embolization can proceed. This strategy (evoked potentials and provocative tests) has proved to be very sensitive: almost invariably, patients with negative provocative tests followed by embolization had a good outcome with no additional neurological deficits. Unfortunately, the specificity of this technique could
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not be tested as embolization is considered too risky in case of positive provocative tests.
Future question and direction What i s n ot e xtensively a ddressed in t he l iterature i s t he t emporal c orrelation between the onset of INM changes and that of neurological deficits. Mizoi et al (9) reported that postoperative sequalae do not appear if recirculation is started within 10 minutes after SEP attenuation. In this study, the shortest temporary occlusion time with resulting new deficit was 6 minutes. SEP disappeared during temporary occlusion in 42 of 97 patients and in all but three eventually returned to baseline after recirculation, with no sequelae. On average, SEP s disappear 8.6 min. after occlusion. T he t hree p atients w here S EP d id n ot r ecover a fter r ecirculation, a ll experienced neurological sequelae. In another study on 76 patients with aneurysms by Schick et al. (16), the sensitivity of SEPs in determining permanent neurological deficits was 57% and the specificity 88%. The extent of recovery of SEP s and the duration of SEP changes strongly correlated with postoperative deficits. With regards to MEPs, Szelenyi et al. (21) reported that temporary clipping was performed more oftern and it was of longer duration in patients with MEP changes (11.8’ vs. 5’). Overall, the disappearanc e of MEP s for more than 10 minutes was likely to be followed by a postoperative motor deficit. In Horiuchi’s study (4), the interval between the manipulation inducing MEP changes to its manifestation ranged between 20 sec. to 7 minutes and between 2 to 6 minutes for SEPs. So, MEP changes tend to occur earlier than SEP changes. The relationship between duration of clipping and neurophysiological changes, as well as that between the duration of INM changes and outcome needs to be further elucidated by future studies. These will be of paramount importance to understand how long INM changes can be tolerated before ischemia progresses to infarction.
Conclusions 1. INM c an b e a pplied i n a n umber o f n eurosurgical t reatments f or v ascular diseases. S imilarly t o w hat oc curred i n o ther f ields o f I NM, o ver t he p ast decade the focus has been on MEPs, which have proved useful to predict and prevent motor impairment. 2. Yet, a multimodality monitoring combining MEPs and SEPs (and BAERs in selected cases) likely provide the best setting to detect and reverse in time an impending vascular injury to neural pathways. 3. These techniques can be applied also in endovascular neurosurgery and the combination of multimodality INM and pharmacological provocative tests represents a valuable advancement in this field.
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Key references 1. Chang S D, Lopez JR, Steinberg GK. The usefulness of electrophysiological monitoring during resection of central nervous system vascular malformations. J Stroke Cerebrovasc Dis. 1999 November - December;8(6):412-422. 2. Friedman WA, Kaplan BL, Day AL, Sypert GW , Curran MT. Evoked potential monitoring d uring a neurysm o peration: o bservations a fter f ifty c ases. Neurosurgery. 1987 May;20(5):678-87. 3. Holland NR. Subcortical strokes from intracranial aneurysm surgery: implications for intraoperative neuromonitoring. J Clin Neurophysiol. 1998 Sep;15(5):439-46. 4. Horiuchi K, Suzuki K, Sasaki T, Matsumoto M, Sakuma J, Konno Y, Oinuma M, Itakura T, Kodama N. Intraoperative monitoring of blood flow insufficiency during s urgery o f m iddle c erebral a rtery a neurysms. J N eurosurg. 2 005 Aug;103(2):275-83. 5. Ichikawa T, Suzuki K, Sasaki T, Matsumoto M, Sakuma J, Oinuma M, Kasuya H, Kodama N.Utility and the limit of motor evoked potential monitoring for preventing complications in surgery for cerebral arteriovenous malformation. Neurosurgery. 2010 Sep;67(3 Suppl Operative):ons222-8 6. Liu AY, Lopez JR, Do HM, Steinberg GK, Cockroft K, Marks MP. Neurophysiological monitoring in the endovascular therapy of aneurysms. AJNR Am J Neuroradiol. 2003 Sep;24(8):1520-7. 7. Lopéz JR, Chang SD, Steinberg GK.The use of electrophysiological monitoring in the intraoperative management of intracranial aneurysms. J Neurol Neurosurg Psychiatry. 1999 Feb;66(2):189-96 8. López JR. Neurophysiologic intraoperative monitoring of pediatric cerebrovascular surgery. J Clin Neurophysiol. 2009 Apr;26(2):85-94. Review. 9. Mizoi K, Y oshimoto T. P ermissible t emporary occlusion time in aneurysm surgery a s e valuated b y ev oked p otential m onitoring. N eurosurgery. 1 993 Sep;33(3):434-40; discussion 440. 10. Neuloh G, Schramm J. Monitoring of motor evoked potentials compared with somatosensory evoked potentials and microvascular Doppler ultrasonography in cerebral aneurysm surgery. J Neurosurg. 2004 Mar;100(3):389-99 11. Neuloh G, Schramm J. Moto r evoked potential monitoring for the surgery of brain t umours a nd v ascular ma lformations. A dv T ech S tand N eurosurg. 2004;29:171-228. Review. 12. Niimi Y., Sala F , Deletis V , Setton A , Bueno de Cama rgo A , Berenstein A : Neurophysiologic Monitoring and Pharmacologic Provocative Testing for
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Embolization of Spinal Cord Arteriovenous Malformations. Am J Neuroradiol 25:1131-1138, 2004. 13. Quiñones-Hinojosa A, Alam M, Lyon R, Yingling CD, Lawton MT. Transcranial motor evoked potentials during basilar artery aneurysm surgery: technique application for 30 consecutive patients. Neurosurgery. 2004 Apr;54(4):916-24; discussion 924. 14. Sakuma J, Suzuki K, Sasaki T, Matsumoto M, Oinuma M, Kawakami M, Itakura T, Kodama N.Monitoring and preventing blood flow insufficiency due to clip rotation after the treatment of internal carotid artery aneurysms. J Neurosurg. 2004 May;100(5):960-2. 15. Sala F , Niimi A , Berenstein A , Deletis V . Neuroprotective role of neurophysiological monitoring during endov ascular procedures in t he spinal cord. Annals of New York Academy of Sciences. Vol. 939: 126-136, 2001. 16. Schick U , D öhnert J , M eyer J J, V itzthum H E. E ffects o f t emporary c lips o n somatosensory evoked potentials in a neurysm surgery. Neurocrit Care. 2005;2(2):141-9. 17. Schramm J, Koht A, Schmidt G, Pechstein U, Taniguchi M, Fahlbusch R. Surgical and electrophysiological observations during clipping of 134 aneurysms with evoked potential monitoring. Neurosurgery. 1990 Jan;26(1):61-70. 18. Symon L, W ang AD, Costa e Silva IE, Gentili F . P erioperative use of somatosensory evoked responses in aneurysm surgery . J Neurosurg. 1984 Feb;60(2):269-75. 19. Suzuki K, Kodama N, Sasaki T, Matsumoto M, Konno Y, Sakuma J, Oinuma M, Murakawa M. Intraoperative monitoring of blood flow insufficiency in the anterior c horoidal a rtery d uring a neurysm s urgery. J N eurosurg. 20 03 Mar;98(3):507-14. 20. Szelényi A, Kothbauer K, de Camargo AB, Langer D, Flamm ES, Deletis V. Motor evoked p otential m onitoring d uring c erebral a neurysm s urgery: t echnical aspects a nd c omparison o f t ranscranial a nd d irect c ortical s timulation. Neurosurgery. 2005 Oct;57(4 Suppl):331-8; 21. Szelényi A , Langer D, K othbauer K, De Camargo AB, Flamm ES, Deletis V . Monitoring o f m uscle mo tor e voked p otentials d uring c erebral a neurysm surgery: intraoperative changes and postoperative outcome. J Neurosurg. 2006 Nov;105(5):675-81.
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EMBRYOLOGY OF AVM AND DAVM Pr. Christophe Cognard I) AVM IA) Introduction Arteriovenous malformations of the brain (b rain AVMs) correspond to cong enital cerebrovascular anomalies, also known as intracerebral or pial AVMs. First of all, it is important to stress the fact that this is not a neoplastic lesion and therefore not an "angioma", which is obviously an inappropriate though commonly used term (ROSENBLUM et al. 1996). Clinically, brain AVMs are an increasingly recognized cause of death and long-term morbidity, mostly due to intracranial hemorrhage and epilepsy; however, they may remain silent over a long period of time, even over an entire life. Anatomically speaking, they are constituted by a complex, tangled web of afferent arteries and draining veins linked by an abnormal intervening capillary bed -- the so-called nidus -- w hich ma y o r n ot h arbor d irect a rteriovenous s hunts ( CHALLA e t a l. 1 995; ROSENBLUM et al. 1996; T HE ARTERIOVENOUS MALFORMA TION STUDY GROUP 1999), of which two categories must be recognized: AV malformations (AVMs) and AV fistulas (AVFs) (LASJAUNIAS and BERENSTEINS 1993). AVMs are composed of a network of channels interposed between feeding arteries and draining veins, without any direct shunt. Two different anatomic types of nidus may be more or less differentiated: compact nidus, constituting a tumor-like wellcircumscribed network, and diffuse nidus, with sparse, abnormal AV channels spread within normal brain parenchyma (CHIN et al. 1992). AVFs are formed by direct communication between an enlarged artery and vein without interposed nidus. Lack of a capillary bed in the AVM nidus results in direct arteriovenous communication, which may be unique or multiple (STAPF and MOHR 2000). AVFs are much more rare than A VMs (2%, LASJA UNIAS and BERENSTEINS 1993) and are always located on the brain surface. They may be present within an AVM n idus as a d irect A V s hunt s urrounded b y t he n etwork o f a rteriovenous channels. AVMs may be situated in any region of the brain, lying mostly within the distribution of the middle cerebral arter ies and involving the hemispheric convexities in continuity with the adjacent leptomeninges; however, they can be restricted to the dura or choroid plexus. They vary in size from cryptic lesions, which remain invisible even on angiographic studies and are discovered on anatomic studies of surgically removed hematomas, to giant AVMs, which can involve a whole hemisphere. Feeding arteries may be one or numerous. They may be very enlarged or present an almost no rmal d iameter. H igh f low m ay p roduce ei ther ( a) s accular a neurysm formation, located at the level of the circle of Willis or the feeding arteries or within the nidus (CUNHA E SA et al. 1992; OGIL VY et al. 2001; LASJA UNIAS et al. 1988; MEISEL et al. 2000; REDEK OP et al. 1998; THOMPSON et al. 1998; TURJMAN et al. 113
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1994), or (b) high-flow angiopathy with progressive stenosis and eventual occlusion of feeding arteries (MAWAD et al. 1984). Draining veins as well may be one or numerous, deep or cortical. Direct shunting of blood at arterial pressure causes dilatation and tortuosity in the involved veins. High flow may also produce localized stenosis, frequently at the level where the veins cross the dura to reach the sinus (MANSMANN et al. 2000; MIYASAKA et al. 1992) and secondary venous aneurysmal dilatation (NATAF et al. 1997). IB) Epidemiology There is very little information in the literatur e about the prevalence of A VMs, i.e., the proportion of a population living with the diagnosis of AVM at a single point in time. Because of the r arity of the disease and the existence of asymptomatic patients, establishing a true prevalence rate is difficult and probably not feasible (STAPF et al. 2000). Considering unselected populations, AL -SHAHI and W ARLOW (2001) found a prevalence of AVMs in a retrospective study in a region of Scotland of 15 p er 100,000 living adults over 16 years of age. In this series, prevalenc e is obviously underestimated, since it does not consider asymptomatic AVMs. Only large post-mortem studies in the general pop ulation could g ive a more accurate estimation of the prevalence of both symptomatic and clinically silent AVM. However, such a series does not exist. Only few hospital-based post-mortem studies are available, in which the prevalence of AVMs was found to be between 400 and 600 per 100,000 (AL -SHAHI and W ARLOW 2001; BERMAN et al. 2000; JELLINGER 1986). This huge discrepancy is obviously due to the fact that the prevalence in living subjects is underestimated, first because of the lack of filling case ascertainment in retrospective s tudies, a nd s econd b ecause t he e ntire g roup o f no nsymptomatic AVMs are not included in the counting because they are not detected. BERMAN et al. (2000) have provided a very interesting paper in which they revi ewed all of the relevant original literature. They conclude that "the estimates for AVM prevalence that are published in the medical literature are unfounded". F or these authors, the most reliable estimate for the occurrence of the disease is the detection rate for symptomatic lesions: 0.94 per 100,000 persons per year. Incidence corresponds to the proportion of a population newly diagnosed with an AVM. Population-based incidence data are also very difficult to evaluate; only two population-based s udies o f A VM i ncidence a re a vailable ( BROWN e t a l. 1 996; JESSURUN et al. 1993), and both are retrospective. Over a 10-year-period (between 1980 and 1990) in the Netherlands Antilles, the annual incidence of symptomatic AVMs was 1.1 per 100,000 per year (JESSURUN et al. 1993). In a second study , using the comprehensive Mayo Clinic medical records linkage system over a 27-year period from 1965 to 1972 in Olmsted County (USA), the incidence of symptomatic AVMs was 1.84 per 100,000 per year (BROWN et al. 1996). Interestingly, the incidence rate increased over time, probably due to the use of more advanced brain imaging modalities. Obviously , a prospective study would give a more accurate estimate of AVM incidence and a better description of the population
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affected by the disease, but such a study is currently lacking. Where other demographic characteristics of patients with brain A VMs are concerned, mean age at diagnosis is between 30 and 40 years (HOFMEISTER et al. 2000; JESSURUN et al. 1993, THE ARTERIOVENOUS MALFORMATION STUDY GROUP 1999) and it affects both sexes in nearly equal proportions (HOFMEISTER et al. 2000; THE ARTERIOVENOUS MALFORMATION STUDY GROUP 1999). Even th ough b rain A VMs a re c onsidered t o b e a c ongenital d isorder, nonsystematized familial AVMs are extremely rare and very few familial cases have been reported in the lite rature (ABERFELD and RAO 1981; HERZIG et al. 2000; KAMIRYO et al. 2000; YOKOYAMA et al. 1991). No genetic predisposition was found and the occurrence of brain A VMs in two members of the same family could be purely accidental. Autopsy data showed that only 12% of AVMs become symptomatic during life (THE ARTERIOVENOUS M ALFORMATION S TUDY G ROUP 1 999), a nd i ntracranial hemorrhage is the most common clinical presentation (AL-SHAHI and WARLOW 2001; HOFMEISTER et al. 2000; THE ARTERIOVENOUS MALFORMATION STUDY GROUP 1999). AVMs typically present as solitary lesions. Multiple brain A VMs occur in approximately 0.3%--3.2% of all cases. Surprisingly enough, WILLINSKY et al. (1990) reported 11 cases of mult iple AVMs among 203 patients (6%). Although m ultiple AVMs may occur spontaneously, they are frequently associated with cutaneous or extracranial vascular anomalies (SALCMAN et al. 1992), such as Rendu-Osler-Weber disease and Wyburn-Mason syndrome. However, the clinical mode of presentation, age and sex of the patient, and anatomic distribution of the lesions are the same as those in patients with single arteriovenous malformations: Rendu-Osler-Weber disease -- also known as hereditary hemorrhagic telangiectasia (HHT) -- is a rare autosomal dominant angiodysplastic disorder with a prevalence estimated at between 2 and 40 per 100,000 people (GUT TMACHER et al. 1995). Rendu-Osler-Weber disease is characterized by multisystemic vascular dysplasia and recurrent hemorrhage of the nose, skin, lung, brain, and gastrointestinal tract. It includes: ( a) m ultiple ca pillary t elangiectasias o f t he s kin a nd m ucosa, a nd ( b) arteriovenous malformations and fistulas located in the liver (30% of the cases) (RALLS et al. 1992), the lungs (15 to 20%), the brain (28%) or the spine (8%). Epistaxis i s t he m ost f requent s ymptom, p resent i n 8 5% o f t he p atients (GUTTMACHER et al. 1995; PORTEOUS et al. 1992). The prevalence of brain AVMs in patients presenting with Rendu-Osler-Weber disease is estimated to be between 4% and 13% (PORTEOUS et al. 1992; ROMAN et al. 1978; WILLINSKY et al. 1990). They have no specific characterisitics, especially regarding location and angioarchitecture. However, multiple AVMs in this syndrome are more frequent than in the general population, with a frequency estimated at around 30% (AESCH et al. 1991; HASEGAWA et al. 1999; JELLINGER 1986; JESSURUN et al. 1993; MATSUBARA et al. 2000; PUTMAN et al. 1996; ROMAN et al. 1978; Sobel and
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NORMAN 1984; WILLEMSE et al. 2000; WILLINSK Y et al. 1990). A recent study of 196 patients with Rendu-Osler-Weber disease (WILLEMSE et al. 2000) showed that 12% had a brain AVM, and 96% of these were low grade (Spetzler-Martin grade I or II). The risk of bleeding has been estimated to be lower than in non-Rendu-OslerWeber disease brain AVMs, ranging from 0.4 to 0.72 per year (KJELDSEN et al. 1999). For s ome f amilies, l inkage h as b een e stablished t o a m utated g ene l ocated o n chromosome 9q, which induces abnormality in endoglin, a transforming growth factor beta-binding protein expressed on endothelial cells (CHEIFETZ et al. 1992; MCALLISTER et al. 1994, SHOVLIN et al. 1997); other linkage studies have established another locus at chromososme 12q, resulting in a mutation in the activin receptorlike kinase gene ("ALK -1" gene), also predominantly expressed on endothelial cells and also related to the same TGF-b receptor system (BERG et al. 1997; JOHNSON et al. 1996). The ve ry r are B onnet-Blanc-Dechaume s yndrome -- also called Wyburn-Mason syndrome, neuroretinal angiomatosis, or mesencephalo-oculo-facial angiomatosis - corresponds to the association of unilateral retinal angiomatosis and a cutaneous hemangioma in an ip silateral trigeminal distribution wit h an A VM located in the midbrain (PATEL and GUPTA 1990; ROSENBLUM et al. 1996; WILLINSKY et al. 1990). In the 25 cases reported by THERON et al. (1974), the lesions involved the op tic nerve, then followed the optic track as a unique continuous nidus or as multiple focal AVMs.
IC) Pathology In macroscopic pathology, brain AVMs are composed of (a) clustered and abnormally muscularized feeding arteries, which may also show changes such as duplication or destruction of the elastica, fibrosis of the media, and focal thinning of the wall; (b) arterialized veins of varying size and wall thickness; (c) structurally ambiguous vessels formed, solely of fibrous tissue or displaying both arterial and venous characteristics; and (d) intervening gliotic neural parenchyma (JELLINGER 1986; MANDYBUR and NAZEK 1990; MCCORMICK 1966; ROSENBL UM et al. 1996) (Fig. 3.1). They anastomose with normal cerebral vessels. Critical to the distinction of the true brain AVM from normal leptomeningeal vessels that may assume the appearance of a malformation in neurosurgical material as a result of artifactual compaction are the former's conspicuous mural anomalies. Chief among these are striking fluctuations in m edial t hickness, a rchitectural d isarray, o r f ocal d isappearance o f t he m edia altogether, or its separation into inner and outer coats by a seemingly aberrant elastic lamina. Numerous abnormalities of the muscular l ayer were identified, including partially developed media, two layers of the media separated by a wellformed internal elastic membrane, total or partial disarray of the muscle coat, and partial absence of the media (MANDYBUR and NAZEK 1990). Previously described large capillaries proved to be postcapillary venules by virtue of having a distinct muscular layer. MANDYBURG et al. performed serial sectioning, indicating that the previously described "polypoid projections" of the media are mostly artifacts, and
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the concept of "arterialization of veins in arteriovenous malformations" could not be substantiated (MANDYBUR and NAZEK 1990; ROSENBLUM et al. 1996). Ultrastructural pathological features of brain A VMs were also studied but consist only in the disorganization of collagen bundles within nidal vessels walls (WONG et al. 2000). Embolization results in endothelial cell disruption with pr eservation of the underlaying subendothelial vessel wall (WONG et al. 2000). Lesions subjected to embolization with bucrylate or polyvinyl alcohol (GERMANO et al. 1992; VINTERS et al. 1986) exhibit a f oreign-body response and may undergo focal necrosis. Entrapped neuropil usually manifests dense astrogliosis, neuronal depopulation, and ferruginous encrustation of included neuroglial elements. Within interstices of AVM, oligodendroglioma-like r egions m ay be encoutered t hat may b e i ntrinsic t o t he underlaying misdevelopment process or the result of abnormal oligodendroglial aggregation caused by the i schemic contraction of entrapped w hite matter (LOMBARDI et al. 1991; NAZEK et al. 1988; ROSENBLUM et al. 1996).
ID) Genetics The majority of AVMs are believed to be congenital, although it is possible that some lesions are acquired. Thus, even though they are developmental anomalies, it is likely that a combination of congenital predisposition and extrinsic factors lead to their generation (CHALLA et al. 1995; CHALOUPKA et al. 1998). The vast majority of cases are sporadic, in which no familial association is observed, and no specific gene mutations have been reported for these AVMs. Although familial brain AVMs are rare, elective screening of individuals with a family history of AVM is recommended (ABERFELD and RAO 1981; AMIN-HANJANI et al. 1998). An exception is the rare setting of Rendu-Osler -Weber disease, mapped to the endoglin gene on chromosome 9q, or the activin receptor-like kinase gene on chromosome 12q, both expressed on endothelial cells and related to the TGF-beta receptor system. It is presumed that the genetic defects in this disease result in a signaling-pathway abnormality , potentially affecting vascular assembly and remodeling. It is not yet known why abnormal vascular morphology is limited to focal AVM lesions and whethe r more common sporadic A VMs also r eflect similar mechanisms of dysmorphogenesis (HADEMENOS et al. 2001).
IE) Hemodynamics The velocity of blood flow is considerably higher through AVMs than through normal brain parenchyma. As a result of the abnormal hemodynamic condition, feeding arteries an d d raining v eins b ecome p rogressively d ilated a nd t ortuous. T he hemodynamic effects of shunt flow through an AVM on the surrounding brain have been implicated in the pathogenesis of pretreatment neurological deficits. In fact,
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AVMs could be compared to vascular "sponges", which consume large volumes of blood, depriving the brain of normal circulation (BARNETT 1980; DUCKWILER et al. 1990; JUNGREIS et al. 1989; SPETZLER et al. 1992; YOUNG et al. 1994). A decrease in the perfusion pressure may place these neighboring vascular territories below the lower limit of autoregulation by a combination of arterial hypotension and venous hypertension. Focal neurological deficits have been attributed to this phenomenon of "cerebral steal" (FINK 1992; MANCHOLA et al. 1993; MARKS et al. 1991; NORNES and GRIP 1980); its reported clinical frequency varies widely but is probably much lower than was previously thought (MAST et al. 1995). M oreover, in the same prospective series, MAST et al. demonstrated that there was no relation between feeding artery pressure or flow velocity and the occurrence of focal neurological deficit.
IF) Physiopathology and Biology The pathogenesis of brain A VMs is currently unknown, but recent work suggests that their genesis and development may be linked to aberrant vasculogenesis or angiogenesis (SHALABY et al. 1995). Indeed, in embryos, vascular morphogenesis is a two-stage process: The first stage -- vasculogenesis -- corresponds to the differentiation of angioblasts into endothelial cells to form the primary vascular plexus. D uring t he s econd s tage - - a ngiogenesis - - t his p rimary v ascular p lexus undergoes remodeling and organization inclu ding recruitment of periendothelial cell support (HASHIMOTO 2001). In both processes, blood vessels are established and r emodeled b y p rotein l igands t hat b ind a nd m odulate t he a ctivity o f transmembrane receptor tyrosine kinases. Recent studies have clarified two main systems o f angiogenesis growth factor a nd the endothelial cell-specific protein tyrosine kinase (HANAHAN 1997). The high-affinity binding receptors of the vascular endothelial growth factor (VEGF-R1 and VEGF-R2) appear to mediate various facets of endothelial cell proliferation, migration, adhesion, and tube formation (URANISHI et al. 2001). A recently discovered group of cytokines, the angiopoietins 1 and 2, and their receptors Tie-1 and Tie-2, play an important role at later stages of vascular development (SATO et al. 1995). More precisely, when VEGF binds to VEGF -R2 during embryogenesis, endothelial cells are created and caused to proliferate. When VEGF binds to VEGF-R1, endothelial cells interact and capillary tubes are formed (FONG et al. 1995; SHALABY et al. 1995). When angiopoietin-1 binds to Tie-2, periendothelial support cells are recruited and caused to associate with endothelial cells (PATAN 1998). When angiopoietin-2 binds to Tie-2, kinase activation in endothelial cells is blocked and vessel structures become loosened. Experimental embryos that are deficient in Tie-2 produce the formation of abnormal enlarged vessels without intervening normal capillaries (SATO et al. 1995), and these abnormal vessels resemble human brain AVMs. Embryos that are deficient in Tie-1 fail to establish the structural integrity of vascular endothelial cells, resulting in
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vascular leakage, edema, and breakthrough hemorrhage. Targeted disruption of angiopoietin-1 in embryonic lethal and associated vascular defects resemble those in the tie-2-deficient model. Angiopoietin-2 has been s hown to be a nat urally occurring antagonist for angiopoietin-1 and Tie-1. Transgenic overexpression of angiopoietin-2 disrupts blood vessel formation in the mouse em bryo (MAISONPIERRE et al. 1997). Interestingly, it has been proven t hat endothelial cell expression of VEGF -R and angiopoietin receptors in endothelial cells is significantly higher in patients with surgically resected brain AVMs than in controls (HASHIMOTO 2001; URANISHI et al. 2001). The significant up-regulation of VEGF and Tie in A VMs may indicate some ongoing angiogenesis, possibly contributing to the slow growth and maintenance of the A VM, and could be of potential use in the therapeutic targeting of these lesions. However, it is currently difficult to attribute abnormal VEGF-R expression to specific pathophysiological features of AVMs. It is likely that biological alterations reflect not only th e s pecific m echanisms t hat tr iggered l esion g enesis b ut a lso s ubsequent nonspecific changes attributable to flow hemorrhage, and other injury responses.
II)DAVFs IIA) Introduction: Intracranial dural arteriovenous fistulas (DA VFs) are acquired transdural arteriolovenous shunt. They are most often encountered in more than 50 years old adult but may be disclosed in newborns. They present with a very wide spectrum of symptoms (pulsatile tinnitus, ocula r s ymptoms, intracranial hypertension, demencia, intracranial hemorrhages, myelopathy…). Depending on their venous drainage they can be either benign without any neurological risk for the patient or on the contrary aggressive carrying a very high risk of intracranial hemorrhage. P erfect understanding of the angio-architecture and venous drainage patterns is mandatory to e valuate t he i ndividual n eurological r isk o f e very p atient. Treatment s trategy basically depends on venous drainage and consequent neurological risk.
IIB) Pathogenesis: Before the middle of the sevent ies, DAVFs were considered as congenital in origin [1-4]. Occurrence in young children [5] and asymptomatic necropsy findings [1] were supposed to confirm this idea. The higher frequency of DA VFs at the level of the skull base or at the tentorium was thought to be due to the delay in the embryologic development of the external carotid territory and to the numerous emissary veins [4, 6]. In 1976 and 1978, Castaignes et al. then Djindjian et al. reported cases secondary to cranial traumatisms, intracranial surgery, or cerebral venous thrombosis (CVT) [7, 8],. A lot of cases firmly related to various etiologic factors were thereafter published
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[[9-12]. Djinjian and Merland described venous anomalies sug gesting sinus thrombosis. They noted that in most of their patients tinnitus was often preceded by a variety of medical illnesses, surgical and obstetric procedures or head trauma [8]. They postulated that sinus thrombosis maybe the initial event that produce pathologic opening-up of physiologic AV shunt. Houser et al. described two cases in which initial angiography occlusion of a sinus r espectively 13 and 33 months prior to subsequent angiographic demonstration of a typical DAVF at the same location [6]. Chaudary et al. presented 4 patients with DAVFs and previous history of head trauma. In one of them an angiography performed 2 months before trauma was normal, angiography one week after trauma showed occlusion of right jugular vein and angiography at six months performed because of a tinnitus showed a DAVF [10]. In another of their cases, a head trauma producing a diastasis of the right lamdoidal s uture the initial angiography was normal and six months f ollow up angiography revealed a transverse sinus DAVF. They concluded that pathogenesis is probably growth of dural arteries normally present in the walls of the sinuses during the organization of an int raluminal thrombus. In 1973, K erber and Newton described a vascular network within the dura considered as complex and far in excess of the expected metabolic needs of a membrane furnishing only mechanical support [13] They postulated that this network unites the entire dura as a single vascular unit and probably serves to supply blood to the entire dura at a relative constant head pressure. The existence of physiological micro arteriovenous shunts is still a matter of debate and Roland et al. [14] considered those shunts as short and wide capillaries rather than true AV shunts. Yasuhiro et al. in a histological study of nine DAVF cases and five controls demonstrated that the essential abnormality was a connection between dural arteries and dural veins within the venous sinus wall. They postulated that sinus hypertension caused by steno-occlusive disease of the venous sinuses triggers the development of fistulous connections in the dural wall. Terada et al. created a surgically induced venous hypertension model in rats by producing a common carotid to external jugular vein by-pass [15]. New acquired AV shunt developed in 13 to 23% of the rats showing that sinus hypertension itself without sinus thrombosis may produce DAVFs development. Finally, two hypotheses can b e p roposed f or D AVFs pa thogenesis. T he f irst b ased o n t he e xistence o f physiological micro-arteriovenous shunts within the sinus wall whic h can develop and create an AVF shunt in case of increased sinus pressure most of the time caused by s inus t hrombosis. T he s econd s uggest t hat v enous h ypertension c aused b y obstruction of venous outflow may reduce perfusion pressure resulting in tissue hypoxia and consequent angiogenesis [15, 16]. Finally, DAVFs must be considered more or less as delayed complication of sinus aggression and mainly cerebral venous thrombosis. Some sinus thrombosis etiologic factors have to be researched. In the paper form Cognard et al. [17], the presence of a suspected etiologic factor such as: - angiographically proven sinus thrombosis, neurosurgical operations, cranial traumatisms, otitis or sinusitis, phlebitis of the lower limb or general surgery (particularly gynecologic surgery in the year preceding DAVF symptoms) in 26% of their patients. Tsai et al. reported angiographic signs of sinus thrombosis in 39% of their cases [16]. It has been showed that in some cases 120
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of DAVFs due to CVT, the first symptoms of the DAVFs occurred a long time after the initial event. Besides, it is well known that lot of CVT (particularly at the level of the transverse sinus) may be clinically silent or associated with minimal headaches and the diagnosis is certainly underestimated. Thus, it seems clear that DAVFs are acquired lesion due to dural sinuses' aggressions and mainly CVT. Lasjaunias postulated that DAVFs being relatively rare and causative factors very frequent another factor ("underlying dural vascular weakness") should be implicated in the development of DAVFs in addition to the venous obstruction. Besides, the question of thrombophilic abnormalities in patients with DA VFs has been discussed in the literature. Izumi et al [18] showed s ignificantly abnormal Ddimer levels in 16/18 patients with DA VFs. Mean value of D -dimer was higher in patients with sinus thrombosis than in those without. D -dimer value rose after endovascular treatment and decreased and nearly normalized in cured patients. Mean values for other thrombophilic factors were in or near normal range. Kraus et al. [19] showed a significantly higher frequency of resistance to activated protein C caused by mutation in the factor V gene leading to factor V Leiden in 22 patients with DAVFs. In another paper they did not find any significantly increased prevalence of others thrombophilic risk factors in DA VFs patients [20]. They concluded from both papers that Factor V Leiden is of pathogenetic significance in the etiology of a subgroup of DAVFs. Besides, little is known about molecular mechanisms invo lved in the initial formation of a DAVF and its subsequent biological behavior. Chaloupka et al. showed that local induction of angiogenesis within the wall of dural sinus may produce DAVF creation on a swine model. They hypothesized that pathological activation of neoangiogenesis might explain both pathogenesis and clinical evolution of DAVFs. Klish et al. [21] showed in eight of ten patients with DAVFs an increased circulating vascular endothelial growth factor (VEGF). Six of seven patients treated by embolization displayed post-procedure decreased VEGF . Interestingly enough, pre-treatment VEGF levels were four times higher in patients with T ype II than in those with Type I DAVFs. Terada et al. also demonstrated that in human dural sinus obtained after DAVF surgery in 4 c ases, a strong immunoreactivity for basic fibroblast g rowth f actors ( bFGF) i n s mooth m uscle c ells, e ndothelial c ells a nd meningeal cells [22]. In conclusion there is still no evidence but some arguments that angiogenic factors play a role in DAVF formation and evolution. Overall, we do not fully understand the pathophysiology of DA VFs, but we can propose some main issue: •
They are acquired lesions mainly occurring in patient of more than 50 years old but they may occur in newborns.
•
They must be considered as a venous disease in which the arteriovenous shunt development is produced by a hyper pressure and/or thrombosis of the sinus.
•
They may be created by various conditions (cranial traumas or surgery, otitis, sinusitis…) but are probably mainly due to sinus thrombosis.
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Initial sinus thrombosis may have as consequence sinuses stenosis or occlusion which together with the AV shunt may impair cerebral drainage.
IIC) Physiopathology: DAVFs ha ve l ong b een r egarded a s a b enign d isease w hen c ompared t o b rain arteriovenous malformations [3]. However , the first descriptions of in tracranial hemorrhage from DAVFs modified this idea and led to the belief that all DAVFs were potentially at risk [1, 2, 5]. First, intracranial hemorrhage was attributed to a pial compartment. The idea that clinical symptoms could be related to the patterns of venous drainage appeared in the literature in 1972, when Houser et al. [6] correlated an giographic f eatures t o t he c linical s ymptoms o f 2 8 p atients. T hey concluded that intracranial hemorrhage occurred when the venous drainage was limited to the pial veins and particularly when associated to a dilated arterio-venous pouch. Subsequently, Kosnick et al. [ 23] observed that DA VFs, although ext racerebral, could present with the same neurological symptoms as brain AVMs. In their review of 96 previously published cases[5] , they concluded that "involvement of the pial v enous s ystem m ay p roduce s ubarachnoid h emorrhages" b ut a lso t hat "increased v enous p ressure a t t he T orcular r egion i nduces h eadaches a nd papilledema". In 1976, the DAVFs draining into cortical veins were considered as a separate group with a higher risk of intra-cranial bleeding by Castaigne et al. [7] . A general classification of DAVFs correlating their pattern of venous drainage with the symptoms was elaborated in 1978 by Djindjian, Merland, and Theron [8] . They assumed that DAVFs draining freely into a sinus only produced benign symptoms, while cortical venous drainage might p roduce aggressive neurological sympt oms and hemorrhage. During the 1980's, many papers reported the particular risk of hemorrhage from DAVFs located at the floor of the anterior cranial fossa and at the tentorium cerebelli [24-29]. Three comprehensive reviews of the literature have recently been compiled. In 1984, Malik et al. [28] studied 223 previously reported cases, and concluded that "lesions related to large dural sinuses are less likely to bleed than lesions with restricted dural outflow". They did not, however , pay attention to other angiographic features and particularly the pattern of venous drainage. In 1986, Lasjaunias et al. presented a meta-analysis of 191 cases [30]. They analyzed the mechanism of neurological manifestations and concluded that "apart from the peripheral cranial nerves palsy due to arterial steal phenomena, central nervous system symptoms appear to be related to passive venous hypertension". Finally, in 1990, Awad et al. [24] reviewed 360 cases reported in the literature and 17 of their own cases to compare the angiographic features of 100 aggressive cases to 277 benign ones (they defined aggressive cases as those with hemorrhage or focal neurological deficit, and benign c ases as the others and e ven those w ith papilledema a nd i ncreased i ntracranial p ressure). T hey c oncluded t hat leptomeningeal venous drainage, variceal or aneurysmal venous dilatations, and galenic drainage correlated significantly with aggressive neurological signs. They further stated that no location of DA VFs was immune to aggr essive neurological behavior. Lalwani et al [31], presented a classification of the transverse/sigmoid sinus 122
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DAVF based upon restriction of the venous outflow. In their classification, DAVF were graded f rom 1 ( no v enous r estriction) t o 4 ( antegrade a nd r etrograde s inus obstruction and cortical venous drainage only). They demonstrated in a series of 25 patients that the grade correlated with the presentation, and elaborated a treatment algorithm.
IID) Classification of DAVFs: DAVFs were first classified according to their venous drainage in 1978 by Djindjian, Merland and Theron [20] . They distinguished four types: Type I: immediate drainage into a sinus or a meningeal vein; Type II: initial drainage into a sinus with reflux into other sinuses or cortical veins; Type III: initial drainage into a cortical vein; and Type IV: initial drainage into a cortical vein with a giant venous pouch. In this original report they considered T ype I DA VF as benign, and the aggressiveness increasing with each type. Cognard et al. [17] reviewed a series of 205 consecutive patients in order t o co rrelate a ggressive n eurological b ehavior o f D AVFs t o a ngiographic patterns. T he initial classi fication of Djindjian, Merland, and Theron was consequently modified in five Types (Table 1 and 2) : •
Type I : drainage into a sinus with a normal antegrade flow direction.
•
Type II : drainage into a sinus with insufficient antegrade venous drainage and reflux : IIa: into sinus(es) only IIb: into cortical vein(s) only. IIa+b: into sinus(es) and cortical vein(s).
•
Type III : direct drainage into a cortical vein
•
Type IV : drainage into a cortical vein with a venous ectasia.
•
Type V : drainage into spinal perimedullary veins.
This s eries c onfirmed s trong c orrelation b etween Type o f v enous d rainage a nd neurological risks. All 84 patients with T ype I DA VFs had benign symptoms. Only one had aggressive symptoms (intracranial hypertension) due to a transverse sinus DAVF with a hypoplasia of the controlateral transverse sinus. In this case, the DAVF was located on the only functional sinus and therefore hindered the normal cerebral venous drainage and venous hypertension. Patients with Type IIa DAVFs had benign symptoms in 63% of the cases, Intracranial hypertension symptoms in 37% but no bleeding. Focal neurological symptoms, venous infarction or hemorrhage occurred only in cases with cortical venous drainage (Type IIb to V). Risk of hemorrhage was higher in case with direct cortical drainage and in case with ectasia on the draining vein. Type V DAVFs (a Type III or IV DAVFs with associated perimedullary drainage) presented in half of the cases with progressive myelopathy as a spinal DAVF. This classification can be applied to all intracranial DAVFs whatever their location. 123
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Borden et al. [32] proposed a simplified classification for both spinal and cranial DAVFs: - Type I DAVFs drain into dural sinus or meningeal veins, - Type II drain into drain into dural sinus or meningeal veins but also with retrograde drainage into subarachnoid veins, - Type III drain directly into subarachnoid veins. This classification was not based on a clinical series and no correlation with aggressive neurological course was made. Davies et al. [33] evaluated the validity of those two classifications in a series of 102 patients with DAVFs. In Cognard classification, aggressive clinical presentation was seen in: - 0% of Type I, - 7% of Type IIa, - 38% of Type IIb, - 40% of Type IIa+b, - 69 % of T ype III, - 83% of T ype IV and 100% of T ype V DAVFs. In Borden classification, aggressive clinical presentation was seen in 2% of Type I, 28% of Type II and 31% of type III DAVFs. We personally prefer using the Cognard Classification which more precisely allows evaluation of patients’ risks and therapeutic decision.
IIE) Location of DAVFs: The m ost f requent l ocation a re t ransverse s inus ( 50%), c avernous s inus (1 6%), tentorium cerebelli (12%), superior sagittal sinus (8%) [17]. Other frequent locations are anterior cranial fossa, Torcular, vein of Galen and straight sinus, superior or inferior petrosal sinus, foramen magnum, or condylar vein. Some comments must be made upon DAVFs locations: •
DAVFs can be observed ever ywhere on the meninges of the cranium and spine.
•
Arteries feeding the DA VFs are meningeal feed ers normally supplying the area where the shunt is located. This may influence the therapeutic strategy and make endovascular treatment difficult or impossible in some location where feeding arteries are distal branches of internal carotid or vert ebral arteries (anterior cranial fossa, tentorium cerebella...).
•
Type of venous drainage depends on DAVFs location. DAVFs located on the wall of venous sinuses (transverse/signmoid, superior sagittal, cavernous sinuses) more often drain directly into the affected sinus (Type I or II). On the contrary DAVFs distant to dural sinuses always drain into cortical veins and are consequently at higher risk of aggressive clinical course.
•
Indeed, many reports have noted the high frequency of neurological symptoms when DAVFs were located at the tentorium cerebelli, the anterior cranial fossa, and the superior sagittal sinus [24-28, 34]. Cognard et al. reported a bleeding risk of 62% for DAVFs at the anterior cranial fossa, 58% at the tentorium, 44% at the Torcular and only 24% at the transverse sinus [17]. However, if only Type III and IV DAVFs were considered, there were no statistical differences in frequency of bleeding according to the locations. The low and not significant difference noted was due to nonaggressive
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symptoms as tinnitus and retro-auricular pain frequently disclosing DAVFs of the transverse sinus before they behave aggressivel y . Therefore, the presence or absence of aggressive symptoms varied with the location of the DAVF b ecause a natomy di ctated t he t ype o f v enous d rainage m ost frequently encountered in each location. However, it is likewise important to note that when comparing the same types of venous drainage, the location did not influence the risk of hemorrhage.
IIF) Epidemiology: DAVFs are supposed to be rare and most of the authors in the literature considered they represent about 10% of all intracranial A V shunts. However, we don’t really know today what is there prevalence and incidence and if they are the same in every country and different ethnic groups. Because they are most often a consequence of various thrombotic sinus diseases their frequency probably differ between countries same as cerebral venous thrombosis. 6.1. Age: We have very little information about DAVFs’ patient population in the literature. In the series of Cognard et al. [17], there were two children of 2 days and 12 years old and 203 adults ranging in age from 18 to 83 years (mean 53 YO). No correlation was observed between age and frequency of aggressive neurological symptoms. 6.2. Sex: In the same paper , aggressive neurological symptoms were encountered in 29% of the female population and in 56.5% of the males. The contingency table between the sex and the two groups of symptoms showed a si gnificant d ifference ( p = .001). B ut t he d istribution o f t he locations a nd c onsequently o f t he t ype o f v enous d rainage w as al so significantly d ifferent b etween m ale a nd f emale (p =.001 a nd p =.006). Females represented 85% of the ICDAVFs of the cavernous sinus and 58% of the cases of the transverse sinus. On the contrary, only 38% of the cases in the other locations wer e females. The venous drainage was a type I in 50% of the female population and in only 29% of the males. On the other hand, only 36% of the ICDAVFs in females presented a cortical venous reflux or drainage (type IIb to type V) whereas it was identified in 57.5% of the males. This explains why agg ressive neuro logical symptoms were encountered more frequently in males (56.5%) than in females (29%).
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CRANIAL DURAL AV-FISTULAS J. Marc C. Van Dijk Introduction Dural arteriovenous fistulas (DAVFs) are a unique neurovascular entity, representing 10 – 15 % of all intracranial arteriovenous lesions. They consist of one or more true fistulas, i.e. direct arteriovenous connections without an intervenin g capillary bed, localized within the dura mater. The angioarchitecture and anatomical location of the shunt clearly discerns DAVFs from the pial arteriovenous malformations (AVMs). Moreover, it is generally accepted that DAVFs are acquired as opposed to the pial AVMs that are thought to be congenital. Therefore, although in the literature in many instances DAVFs have been referred to as ‘malformations’, the term ‘fistulas’ is preferred. According to its name a DAVF can be found anywhere along the dura mater, both cranial and spinal. Though, the presentation and clinical behavior of spinal lesions is quite different from that of lesions in the cranial compartment. Spinal DAVFs lead to venous hypertension in the perimedullary venous plexus, nearly without exception causing m edullary v enous c ongestion t hat i nitiates a c hronic p rogressive myelopathy. Remarkably, there is a negligible chance on a spinal hemorrhage. On the contrary, the cranial DAVFs demonstrate a very wide and diverse spectrum of clinical signs a nd sy mptoms d epending o n t heir a ngioarchitecture. I n p articular t he occurrence of hemorrhage, non-hemorrhagic neurological deficits and death are hereby related to a venous congestive encephalopathy, similar to the spine.
Pathogenesis The etiology of DA VFs is still unknown, although many speculations have been forwarded. It has already been mentioned that these lesions are generally accepted to be acquired, since their occurrence has been described after surgery, after head trauma, and in relation to sinus thrombosis, although the exact pathway has never been unequivocally demonstrated. Two hypotheses of pathogenesis have been proposed. The first hypothesis claims that DAVFs arise from ‘dormant’ channels between the external carotid circulation and the v enous pathways within the dura mater. Histopathological and radioanatomical studies have shown that these communications are norma lly present in the dura. The channels open due to the venous hypertension associated with sinus thrombosis or sinus outflow obstruction. A variation to this theme i s the r eported existence of thin-walled venous pouches within t he dura, close to small dural arter ies. Rupture of t hese fragile pouches induces arteriovenous communications within the d ura. The second hypothesis claims that DAVFs are the result of newly grown vascular channels due to provoked angiogenetic factors. These factors, such as VEGF and bFGF , may originate either directly from the clot-organization of a sinus thrombosis or indirectly through a 126
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mechanism of tissue hypoxia induced by an increased intraluminal venous pressure. Rothbart et al reported the positive staining of an excised shunting vein of a DAVF for VEGF and bFGF, supporting the hypothesis that angiogenetic factors most likely play a role in the genesis of DAVFs. Also, research groups produced an experimental rat-model, in which they were able to induce the genesis of a dural A VF in vivo by a combination of venous thrombosis and venous hypertension.
Classification In c oncert w ith s everal a uthors t he t erms ‘ benign’ a nd ‘ aggressive’ a re u sed throughout the literature in relation to the different types of cranial DAVFs and their typical signs and symptoms. In this concept features such as non-hemorrhagic neurological deficits (NHND), hemorrhage and death are considered ‘aggressive’, while co mplaints o f c hronic h eadache, p ulsatile b ruit an d o rbital s ymptoms including cranial nerve deficits due to cavernous sinus lesions are considered ‘benign’, even though they might be regarded as intolerable by the patient. Through the years the anatomical loc ation of a DA VF has gained undeserved recognition as a characteristic or classifying feature. Aminoff already arranged the cranial DAVFs according to their location by separating an anteroinferior group and a posterosuperior group. Since then several large studies have pointed out a relation between the location and the behavior of the DA VF. Following Malik it is however hypothesized that cranial DAVFs in some locations due to the local venous anatomy, e.g. the absence of a venous sinus in the direct vicinity, have a higher likelihood of developing CVR. Although no location of a cranial DAVF is immune from aggressive behavior, certain regions therefore raise the index of suspicion for the development of CVR. Several classification schemes for cranial DA VFs have been introduced, of which nowadays the classifications of Borden and Cognard are the most widely used. Although t he t hree-step c lassification o f B orden h as t he a dvantage f or b eing relatively simple to apply, the Cognard classification (a revision of the Djindjian classification scheme) is theoretically superior , since it incorporates the additional effect of the flow-direction in the dural sinus. Retrograde flow can prohibit the cortical veins to drain into the involved sinus and can subsequently lead to venous congestion of the brain, without the occur rence of CVR. Both classifications have been validated. As such, cranial DAVF categorized as Borden 1, Cognard I or Cognard IIa are to be considered ‘benign’, while all higher Borden and Cognard grades are to be respected as ‘aggressive’ DAVFs, with all its consequences. Lasjaunias p roposed a ne w c lassification b ased o n t he v enous d rainage o f t he epidural s paces a ccording t o t he e mbryology o f t he s tructures s urrounding t he central nervous system, consisting of 3 subgroups: ventral, dorsal and lateral. The three ve nous e pidural s ubgroups c orrespond t o t he s kull b ase, ca lvarium a nd vertebra. The ventral epidural shunts have a female predominance and typically have no cortical venous reflux unless there is high flow or venous thrombosis of the
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epidural venous drainage. The dorsal epidural shunts are often seen in the pediatric age group, are frequently multiple and typically have no cortical venous reflux unless there is extensive venous thrombosis or the shunts are high-flow. The lateral epidural shunts have a male predominance, present at a later age and always have cortical venous reflux.
Treatment In all fields of Medicine, the rule is that treatment should only be instituted if the expected outcome, including the inherent complications, is superior to the natural course of the disease process. In case of cranial DAVFs without CVR the natural disease course is benign in the vast majority of the cases, indicating that observation with angiographic reevaluat ion in case of a sudden or unexpected change of symptoms offers the best management results. In case of aggressive DAVFs (with CVR) the natural history is ominous with a high annual risk on neurological deterioration or death. Therefore prompt treatment is warranted, aimed at the elimination of the CVR by simple disconnection of the refluxing cortical veins from the fistula. Obliteration of the fistula is not mandatory for clinical cure, since DAVFs without CVR follow a benign and self-limiting disease course. Endovascular embolization has been shown to be a valid option, but the same has been demonstrated for open surgical therapy. Although its results have been reported, there is virtually no role for radiosurgery in the treatment of cranial DA VFs. Cranial DAVFs without CVR have a benign natural history, so any additional risk from radiosurgery in the treatment of these lesions is unacceptable. Cranial DAVFs with CVR have a dire disease course after their usually aggressive presentation, with high annual numbers of mortality and morbidity. Even if radiosurgery is effective in these cases, the expected result comes only years after treatment, which delay is improper.
Conclusion Dural AV-Fistulas remain a unique but obscure neurovascular entity. The key feature for clinical practice is the existence of cortical venous reflux. If present, the natural history of the disease forces to aim treatment at the elimination of the CVR, either surgical or with endovascular means. F or the future, the search for the etiology of DAVFs should be continued in order to find a cure for the biological disorder instead of continuously hunting the anatomical expressions of the underlying disease.
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SPINAL VASCULAR MALFORMATIONS Veit Rohde Georg-August-University Goettingen, Germany
Objective Spinal vascular malformations are exceedingly rare. A few classifications exist to characterize the different spinal vascular malformations. An easy and in my opinion practicable classification is given by Spetzler at al., who divided the lesions into three broad categories: The first category consists of neoplasms and includes the truly neoplastic hemangioblastoma and the cavernoma. The second category is the spinal cord aneurysm. The third category is the arteriovenous lesion w hich is s ubdivided into 1-dural arteriovenous fistula (DAVF), 2- intradural, perimedullary arteriovenous fistula (PMAVF) and 3- intramedullary arteriovenous malformation (AVM). It is the objective of the presentation to review the actual literature and the own data base to outline th e signs and sym ptoms, the patho physiology, the di agnostic work u p and the therapy of the lesions of the third category.
Modern literature review The subdivision of the the arteriovenous lesions into DAVF, PMAVF and AVM is based on their neuroanatomy, which guides the therapy. DAVF: The DA VF is the most frequent spinal vasc ular malformation. The fistula between a radiculomeningeal artery and the corresponding radicular vein within the d ural r oot s leeve r esults i n a r etrograde a rterialisation o f t he v ein. T hat arterialisation hinders the normal venous outflow of the spinal cord leading to spinal cord c ongestion a nd, t hereby, t o c hronic m yelopathy ( Hassler 1 989). T he i nitial symptoms are vague, and delay of the correct diagnosis is common. At presentation, 63 – 100 % of the patients ha ve sensory disturbances, 78 – 100 % gait and motor disturbances, 17 – 86 % pain (Jellema 2006). DAVFs never bleed. T2-weighted magnetic resonance (MR) images typically show intramedullary hyperintensity due to venous congestion / edema and the flow voids on the spi nal cord surface, representing the tortuous and dilated arterialized veins. These vessels enhance after gadolinium administration. F or exact loc alisation of the fistula, and for differentiation from other types of vascular malformations, spinal angiography still is indispensable. Most DA VFs are located in thoracic levels. Untreated, DA VFs inevitably result in severe morbidity. In general, two treatment options, either endovascular embolization or surgical interruption of the fistula, exist. In recent studies in which N-butyl 2-cyanoacrylate or other liquid embolic agents were used for embolization, occlusion rates between 70 an d 90 % had been achieved (Sivakumar 2009). Using microsurgery, occlusion rates between 98 and 100 % were obtained (Steinmetz 2004). If the fistula is disconnected at the very first intradural segment of the arterialized vein, the surgical complication rate is very low. There is an ongoing discussion if embolization or microsurgery should be the first line 129
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treatment. If the fistula is successfully occluded, clinical improvement in the majority of patients could be expected (Jellema 2006). Early deterioration possibly is related to thrombosis of the arterialized veins, and late deterioration to progressive atrophy of the spinal cord. PMAVF: The fistula is located on the pial surface and directly connects a spinal artery with a p erimedullary v ein. P MAVFs a re e ither l ocated d orsolaterally o r s trictly ventrally because of the arterial supply of the spinal cord by 2 dorsolateral arteries and one anterior spinal artery. As in DAVFs the arterialisation of the perimedullary vein results in venous congestion and in myelopathy . Thus, the clinical course can resemble that of a DAVF. However, in contrast to DAVFs, PMAVFs has the propensity to bleed (Antonietti 2010). The MR images mostly resemble that of DA VFs with an intramedullary h yperintensity a nd f low v oids o n t he s pinal c ord su rface o n T 2weighted MR images. Angiography is required to differentiate between DAVF and PMAVF, and to define the fistula site. T reatment options are embolization and microsurgery. For successful embolization the catheter has to be positioned within the afferent spinal artery close to the fistula point which could be difficult if the calibre of the vessel is small. Especially in dorsolat eral PMAVFs which are easi ly accessible by a standard dorsal approach, microsurgery often is the preferred treatment option. Coag ulation of t he first segment of the arterialized vein is sufficient for cure. In ventrally located PMA VFs embolization often is given the preference because of the difficulty to access the anterior surface of the spinal cord surgically. T herapeutic c hallenges a re v entral P MAVFs w hich a re f ed b y a s mall anterior sp inal a rtery; i n t hese c ases t ransmedullary a pproaches a long a transmedullar arterialized vein could be feasible (Giese 2010). The occlusion rates for embolization, embolization plus surgery , and surgery alone vary between 75 and 82 % (Antonietti 2010). If the PMAVF is successfully obliterated improvement of the neurological symptoms could be expected in half of the patients. Spinal A VM: S pinal A VMs r esemble b rain A VM w ith f eeding a rteries no rmally supplying the spinal cord, with a nidus in the parenchyma, and with draining arterialized veins. The arterialisation of the veins results in venous congestion of the spinal c ord a nd i n s ymptoms w hich c ould b e a ttributed t o a cute a nd c hronic myelopathy. O ften, t he p atients b ecome s ymptomatic d ue t o i ntramedullary o r subarachnoid h emorrhage ( Boström 2 009). M R i mages s how t he m edullary congestion / edema, the vessels and the nidus, and are required to assess the surgical accessibility. Spinal angiography is necessary to gain a full understanding of the angioarchitecture o f t he A VM. T he f irst t reatment o ption i s e mbolization. Microsurgery sh ould b e c onsidered i f t he A VM i s d orsally l ocated a nd, t hus, accessible without morbidity, and if embolization fails. Only one larger series and a few case series has been published so far, but these publications suggest that, in contrast to brain AVMs, even incomplete occlusion of the AVM produces favourable results with a low risk of re-bleed and symptom relief.
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Recent clinical and research development Recent clinical developments focus on the evaluation of new embolization material (Onyx) for the treatment of DAVFs and other spinal vascular lesions. Up to now, the published series are too low to define if occlusion rates comparable to surgery could be achieved. In DA VFs new adjuncts to facilitate surgery or improve the operative results such as coiling the radicomeningeal artery for easier identification of the fistula on intraoperative fluoroscopy , or intraoperative ind ocyane green videoangiography had been proposed (Hanel 2010). The value of advanced MR or CT angiography for diagnosis and localisation of DA VFs and PMA VFs is currently investigated with the aim to replace invasive and time-consuming spinal angiography.
Future questions and direction In the future a better understanding on the development of spinal vascular lesions would be warranted. First attempts had been made to identify genetic factors which might be related to occurrence of spinal vascular malformations. Due to the rarity of spinal vascular malformations a registry for structured and prospective data collection should be installed in the future. Improvement in imaging technologies further will contribute to a thorough understanding of the angioarchitecture of more complex spinal vascular lesions.
Conclusion Spinal arteriovenous lesions (Category 3 - Spetzler classification) are rare. Among those the dA VF is the most frequent, followed by the PMA VF and the true A VM. Venous congestion due to arterialisation of spinal cord draining veins with resultant myelopathy is common in all 3 lesions. Only PMA VFs and A VMs can become symptomatic by bleeding. DAVFs are treated either by embolization or microsurgery, with h igher o cclusion r ates u sing s urgery. Do rsolateral P MAVFs p referentially undergo surgery, ventral PMAVFs preferentially embolization. In AVMs embolization is the first line therapy.
Key references and recommended reading •
Antonietti L, Sheth SA , Halbach VV, Higashida RT, Dowd CF, Lawton MT, English JD, Hetts SW : Long-term outcome in the repair of spinal cord perimedullary arteriovenous fistulas. AJNR Am J Neuroradiol 31: 1824-1830, 2010
•
Boström A, Krings T, Hans FJ, Schramm J, Thron AK, Gilsbach JM: Spinal glomus-type arteriovenous malformations: Microsurgical treatment in 20 cases. J Neurosurg (Spine) 10: 423-429, 2009
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Giese A, Winkler A, Schichor C, Kantelhardt SR, Boeckh-Behrens T, Tonn JC, Rohde V: A transmedullar approach to occlusion of a ventral perimedullary arterio-venous fistula of the thoracic spinal cord. Neurosurgery 66: 611615, 2010
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Hanel RA, Nakaji P, Spetzler RF: Use of microscope-integrated near-infrared indocyanine green videoangiography in the surgical treatment of spinal dural arteriovenous fistulae. Neurosurgery 66:978-84, 2010
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Hassler W, Thron A, Grote EH: Hemodynamics of spinal dural arteriovenous fistulas. An intraoperative study. J Neurosurg 70:360-70, 1989
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Jellema K, Tijssen CC, van Gijn J: Spinal dural arteriovenous fistulas: a congestive m yelopathy t hat i nitially m imics a p eripheral n erve d isorder. Brain 129: 3150-3164, 2006
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Spetzler RF, Detwiler PW, Riina HA , Porter RW: Modified classification of spinal cord vascular malformation. J Neurosurg (Spine 2) 96: 145-156, 2002.
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Sivakumar W, Zada G, Y ashar P, Giannotta SL, Teitelbaum G, Larsen DW : Endovascular management of spinal dural arteriovenous fistulas. Neurosurg Focus 26 (5): E15, 2009
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Thron AK: Vascular anatomy of the spinal cord. Springer Wien-New York, 1988
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INTRAMEDULLARY SPINAL CORD CAVERNOMAS (IMSCC) Yury Kushel, MD Burdenko Neurosurgical Institute General information Cavernomas are vascular lesions consisting of sinusoidal vascular channels lined by layer of endothelium. They may be found throughout the CNS . Exact populational data about spinal cord cavernomas does not exist. In expert's surgical series this pathology constitute 3-5% of intramedullary lesions and is subject of refferal bias.
Clinical picture and imaging In pre-MRI era the diagnosis of IMSCC was extremly rare and done by either autopsy or a t t ime o f s urgery. Th e i ntroduction o f M RI p ermitted th e i dentification a nd subsequent study of cavernomas because they have characteristic appearance with MRI. Cavernomas possess a dark rim around a hyperintence core lesion on T2 that is caused by hemosiderin deposition around the cavernoma. There are several «classifications» of IMSCC cl inical course (see ref .2;4). F rom practical point of view it is usfull to divide all of them into INCIDENTI AL and SYMPTOMATIC. Most common symptoms are radicural pain and mild mielopathy.
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Natural history The natural history of IMSCC are not well studied and described. All studies have biases. The clinical course described in literature has wide rage from recovery after mild hemorrages to fatal hemorrages with para/tetraplegia and no recovery after surgery. Bu t a s g eneral – t his p athology i s r elatively b enign a nd e xperts d o n ot support «profilactic surgery».
Treatment Surgery is main treat ment modality fo r symptomatic l esions. Only radi cal surgery has sence. CM remnats have same risk of rebleeding (see ref.3) as virgin cavernoma. There is good study of natural history of conservatively managed IMSCC (see ref.1). 1. in my personal surgical serie it is 9 of 283 operated IMSCT (3%) Unfirtunately ( or f urtunately) w e w ill n ever g et d efinite a nswer a bout t he b est treatment strategy because of rarety of these lesions.
Personal remarks I will propose surgery to any young and middle-aged patient with symptomatic IMSCC with signs of previouse bleeding. I will wait and scan in INCIDENTIONAL case. And I will take «patient-tailored» decision in all other cases of intramedullary spinal cord cavernomas. It is impossible to estimate surgical risks without regard for personal surgeon's experience in intramedullary surgery.
Interesting literature on the topic 1) Kharkar, Siddharth; Shuck, John; Conway , James; Rigamonti, Daniele. The Natural History of Conservatively Managed Symptomatic Intramedullary Spinal Cord Cavernomas. Neurosurgery. 60(5):865-872, May 2007. 2) Ogilvy, Christopher S.; Louis, David N.; Ojemann, Robert G.. Intramedullary Cavernous Angiomas of the Spinal Cord: Clinical Presentation, P athological Features, and Surgical Management. Neurosurg ery. 31(2):219-230, August 1992. 3) Vishteh, A. Giancarlo; Sankhla, Suresh; Anson, John A.; Zabramski, Joseph M.; Spetzler, Robert F. Surgical Resection of Intramedullary Spinal Cord Cavernous Malformations: Delayed Complications, Long-term Outcomes, and Association with Cryptic Venous M alformations. Neurosurgery. 41(5):1094-1101, November 1997. 4) Zevgaridis D., Medele RJ.,Hamburger C., Steiger HJ, Reulen HJ. Cavernous hemangiomas of spinal cord. A review of 117 cases. Acta Neurochir (Wien) 141:237-245, 1999 134
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DIAGNOSTIC EVALUATION IN INTRACEREBRAL HEMORRHAGE Niklas Marklund, MD, PhD, Neurosurgeon, Uppsala University Hospital, Uppsala Sweden
Objective •
To provide an over view of the most common underlying causes for intracerebral haemorrhage (ICH) and their diagnostic work-up.
•
To provide the resident with take-home recommendations for the immediate evaluation and late follow-up of ICHs.
Background Intracerebral haemorrhage (ICH) carries a high mortality and morbidity. Correct and timely diagnosis of possible underlying causes of ICH directs treatment to improve outcome or prevent recurrent ICH (Cordonnier et al., 2010). In the acute setting, an important t ask i n n on-traumatic I CH is t o f ind o ut w hether t he h emorrhage i s secondary to e.g. an AVM, aneurysm, or dural sinus thrombosis. Thus, neurosurgeons will frequently be consulted with images of ICHs not only to decide if surgery is a treatment option but also to aid i n the initial dif ferential diagnosis crucial to early management. ICHs associated with hypertension are predominately located in central hemispheric tissue whereas lobar supratentorial ICHs may have numerous potential underlying causes. Clinical and CT features with a higher likelihood of indentifying a vascular causative pathology on neuroimaging include age< 4 0-50 y ears, a bsence o f h ypertension o r c oagulopathy, p resence o f subarachnoid or intraventricular blood, and temporal or frontal lobe ICH location (see Delgado Almandoz et al., 2009). However, these factors cannot be used alone to rule out underlying vascular pathology, and 24% of patients unlikely to have an associated vascular condition on CT scan were diagnosed with one using DSA (Halpin et al., 1994). Although a degree of individual opinion and decisions is allowed in the work-up of ICHs, some suggest ions and guidelines derived from r ecent literature are provided in the next sections.
Imaging options
CT, contrast-enhanced CT (CECT), CT angiography (CTA), CT venography CT is suitable for emergency evaluation and still the predominant presurgical and premedical imaging option for ICH, being much quicker than MRA or DSA (Romero et al., 2009). Multidetector row CT A is noninvasive, frequently available, and advantageous for agitated or confused patients. In most patients, the presence of an acute ICH is straightforward showing a hyperdense lesion (50-70 Hounsfield Units, HU ). M any I CHs i ncrease i n s ize o n r epeated i maging. T he a ge o f t he hematoma may not be easily defined although the attenuation decreases ~1.5 135
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HU/day, r esorption b eginning i n p eriphery a nd t he I CH b ecomes p rogressively isodense and then hypodense (Fig. 1). Perihaemorrhage oedema may increase up to 14 days following the onset of ICH (Schellinger et al., 2003).
Fig. 1. Typical appearance of the evolution of an ICH at day 2 (left) and day 13 (right) When using CECT, a ring-like enhancement lesion occurs at a few days following the ICH onset persisting up to 2-6 months following the ictus. Using CT A (or CECT), contrast ex travasation i nto t he h ematoma, t he “ spot-sign”, s uggests o ngoing bleeding with a high risk of hematoma expansion and increased mortality (Delgado Almandoz et al., 2010). CTA and CT venography (CTAV) correlates well with DSA for the detection of A VMs, aneurysms, lobar ICHs and neoplastic ICHs (W ong et al., 2011; Yoon et al., 2009; Romero et al., 2009).
MRI/MRA MRI and CT show equal ability to identify the presence, size and location of an acute ICH. However, MR is superior to CT at detecting underlying structural lesions and delineating the amount of perihematomal edema and herniation (Broderick et al., 2007) a lthough n ot f or d iagnosing t he a ge of t he I CH ( see T able 1 f or M R interpretation). The appearance of ICH on MR depends on a variety of technical and biological variables, including field strength, sequences and age of the ICH and 3T MRI data on ICH are scarce, to date. MRI yield is highest in hemorrhagic ischemic stroke, cerebral amyloid angiopathy (CAA), AVM and neoplasms and is superior to CT for the identification of cavernoma and previous hemorrhages. MRI within 3 days from onset was shown to alter diagnosis in 14% and alter management in 20% of patients when compared to standard CT imaging (Wijman et al., 2010).
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Table 1. MR characteristics for ICH, modified after Linn and Brückmann, 2010. Digital subtraction angiography (DSA) DSA is still the gold standard to rule out or confirm AVMs or dAVFs, and is superior for t he a ssessment o f d etailed a ngioarchitecture c ompared t o C TA. O bvious indications for DSA in ICH management include presence of subarachnoid hemorrhage, p resence of a bnormal c alcifications o r “ pure” i ntraventricular hemorrhage. The yield of angiography declines in elderly patients with hypertension and central ICHs and the up to 1% risk of symptomatic cerebrovascular complications must be considered. Although previous studies have suggested that patients > 45 y ears w ith p reexisting h ypertension w ith c entral I CHs s hould n ot routinely undergo DSA (see Cordonnier et al., 2010), unexpected findings even in these patient categories do occur (see Table 2). Finally, if vasculitis is suspected, DSA is superior to CTA or MR/MRA.
Table 2. Yield of DSA in a cohort of 726 patients from 9 studies; modified from Cordonnier et al., 2010.
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Differential diagnosis
Small vessel disease associated with hypertension Chronic arterial hypertension results in microangiopathy, affecting small penetrating arteries (50-200 µm) most frequently but not exclusively from the MCA territory . Typical locations include the basal ganglia and thalamus, although up to 10% occur in t he p ons o r c erebellum ( Linn a nd B rückmann, 2 010) a nd w idespread c entral microhemorrhages may be observed. It should be noted that a proportion (5-15%) of lobar ICHs may also be associated with hypertension. In these patients, MRA , CT A or DSA imaging i s frequently normal.
Fig. 2 Typical appearance of central ICH associated with hypertension
Cerebral amyloid angiopathy (CAA, defined as β-amyloid protein deposition in wall of blood vessels of the cortex and leptomeninges) most commonly occurs in elderly people (>70 years). Besides being a frequent cause for lobar macrohemorrhage, widespread microbleeds ( oligodendrocytes > a strocytes > m icroglia. H ence, t here i s a n i nverse r elation between the CBF within the penumbra and duration the tissue within the penumbra
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will remain viable. Thresholds, similar to the thresholds for CBF exists for oxygen tension (PaO2). If P aO2 decreases below 65 mmHg (8.6 kP a) impaired mentation results, at 55 mmHg (7.2 kPa) memory is disturbed, below 30 mmHg (4 kPa) loss of consciousness occurs, and below 15 mmHg (2 kPa) infarction occurs.
In experimental models of infarct and peri-infarct penumbra zones, depolarisation waves s preading f rom t he c entre o f i schemia ha s b een d emonstrated. S uch depolarisation waves sever ely drains the already depleted metabolic reserve a nd hence pushes the zone, from being an ischemic penumbra zone, towards a zone of irreversible ischemia. Recently such spreading depression-like depolarisations have been demonstrated in patients following trauma or subarachnoidal haemorrhage (SAH). Th e s tandard p hysiological r esponse t o s preading c ortical d epression i s vasodilatation, securing the energy inflow to restore haemostasis. However, in some cases a resultant vasoconstriction is seen, resulting in severe ischemia.
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Conclusion Increased knowledge of cerebral blood flow regulation, metabolism and ischemia through research, is going to be one of the very prominent players in improving the outcome for patients with cerebrovascular diseases, whether primary of an ischemic or hemorrhagic nature.
References Al-Tamimi YZ, Orsi NM, Quinn AC et al. A review of delayed ischemic neurological deficits following aneurysmal subarachnoid hemorrhage: Historical overview, current treatment, and patophysiology. World Neurosurgery 2010;73(6):654-67 Astrup J, Symon L, Branston NM, Lassen NA. Cortical evoked potential and extracellular K+ and H+ levels of brain ischemia. Stroke 1977;8:51-57 Dreier JP, Major S, Manning A , et al. Cortical spreading ischemia is a novel process involved in ischaemic damage in patients with aneurysmal subarachn oid haemorrhage. Brain 2009;132:1866-81. Ryszard M P, H ansen-Schwartz J , D reier J , e t a l. C erebral v asospasm f ollowing subarachnoid hemorrhage: time for a new world of thought . Neurol Res 2009;31(2):151-8 Zauner A, Daugherty WP, Bullock MR, W arner DS. Brain oxygenation and en ergy metabolism: Part I – Biological function and pathophysiology. Neurosurgery 2002; 51: 289-302
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RECONSTRUCTIVE SURGERY IN CEREBRAL ISCHEMIA Endarterectomy versus stenting Vladimír Beneš Dept.Neurosurgery, 1st Faculty of Medicine, Charles Univ., ÚVN Střešovice, Prague, Czech Republic, mail
[email protected]
Objective. To s ummarise r ecent s urgical/interventional t reatment o ptions i n p atients w ith cerebral ischemia. The importance of the topic is obvious – stroke is the third leading cause of death and undoubtedly the leading cause of disability . Some 90% of all strokes is ischemic. Speciál emphasis will be directed to carotid endarterectomy and stenting.
Recent clinical and research development Surgery of the brain arterial supply is performed for stenoses and occlussions of brain supplying arteries, either to revascularise the brain or to exclude the source of brain embolization. Pathophysiologically, the embolic origin from a distant source is far more common than either hemodynamic origin or localised intracranial thrombosis. Atherosclerosis is almost exclusive underlying disease which means that patients treated are generally and seriously ill. Rather typical combination is cerebral ischemic symptoms in a patient with arterial hypertension, diabetes mellitus and ischemic h eart d isease. Th us, i ndividual r isk f actors h ave t o b e c arefully a nd pertinently assesssed prior to any active measures are taken (both, diagnostic and therapeutic). Clinical presentation is variable - asymptomatic lesions, TIAs, completed strokes (usually minor ones), stroke in evolution, rarely global isc hemia. In the diagnostics regular angiography retains its golden standard position to be supplemented by many n on-invasive t echniques s uch a s u ltrasonography, C T, M R, C T o r M R angiography, perfusion CT, XeCT CBF flow studies, SPECT and PET studies, etc. In each patient the brain arterial supply must be considered in its entirety (Fig.1.), i.e.from the heart down to the brain parenchymal network. In each patient usually three different sources of clinical symptoms can be and should be considered and evaluated – heart, magistral vessels, small brain vessels . Any surgical indication should be based upon the careful and detailed evaluation and considered in the light of evidence-based medicine (EC-IC bypass study, NASCET, etc.). Surgical possibilities are numerous and they will be listed bellow. However, in general there are 2 major possibilities of intervention: 1. Directly at the site of the lesion (e.g.carotid endarterectomy - CEA) or 2. Bypass procedures (e.g.EC -IC bypass). Decompressions for the ischemic mass-lesions do not fit into these 2 groups and they will be mentioned separately . Prior to the descriptio n of the sur gical possibilities, few important facts should be noted: 161
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1. All surgical procedures with very few exceptions are preventive measures, the surgical procedures are considered a means of secondary prevention in the treatment of a patient with cerebral ischemia. Thus, the majority of procedures are performed on an elective basis, few emergency or urgent options will be described separately. 2. With a therosclerosis b eing t he u nderlying c ause of c erebral i schemia, a ll patients must be adequately and life-long treated and followed. 3. For a ll p atients m anaged f or s ymptomes o f c erebral i schemia t he m ost dangerous condition is even small and short blood pressure decrease. Such a drop may cause permanent and catastrophic ischemic brain damage. During the surgery/intervention the BP is maintained some 20-30 mm Hg above the patients normal level. After the surgery/intervention the BP is continuously monitored and maintained at n ormal/slightly elevated levels for at lea st 24 hours 1. Aortic arch and its branches. The most common indication is the subclavian steal syndrome caused by either brachiocephalic trunk or subclavian artery stenosis/occlusion. Th e p atients ty pically p resent s ymptoms o f t ransient vertebro-basilar ischemia The treatment of choice is carotido-subclavian bypass which allows normalisation of the reversed vertebral artery flow and thus symptoms alleviation. Recently the interventional techniques should be considered f irst, e ither s tenting o r s imple P TA p rocedures m ay s olve t he stenosis and rarely even the occlusion. Not commonly is the neurosurgeon faced with thoracic outlet syndrome which may be caused by cervical rib, scalenic muscles compression or by the compression from C7 megatransversus. Various decompressive procedures are then employed. 2. Carotid artery (CA). The most commonly involved region is carotid bifurcation. Many and various surgical procedures are available. In this region also the surgery dominates over the interventional neuroradiology. a.
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Carotid stenosis. Endarterectomy (CEA) is the thrid most common surgical procedure and the first most frequent in vascular surgery. The reasonable and recently much studied alternative to CEA is carotid stenting (CAS, Fig.2.). The indications for CEA are well established (NASCET, ECST, ACAS, VA, Mayo). Whenever considering surgery, the AHA recommendations s hould always be kept in mind, i.e.symptomatology, stenosis degree, institutional morbidity/mortality rate ( MM), p atients g eneral r isks. In g eneral, A HA r ecently recommends CEA for patients with relevant symptoms and 50%+ stenosis at institutions with MM rate bellow 6% and in asymptomatic patients for stenosis 60%+ and MM rate bellow 3%.
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However, we see few unaddressed issues in CEA . Firstly , it is symptomatology. In all large studies asymptomatic stenosis was the one fr om which no symptomatology occured within the last six months. We thus find actually three groups of patiens. Those with symptomatology relevant to the stenotic vessel (NASCET patiens) – symptomatic patient, symptomatic vesel (SS). Second group are patients neurologically symptomatic from other territories but with asymptomatic stenotic vesel (AS) and the third group are completely asymptomatic p atiens ( AA). In o ur h ands t hese g roups ex hibit different MM in CEA group but the same MM in CAS patients (Tab.1.). The differencies are not statistically significant but they lead us to be more strict in surgical indications for AA patients and also we avoid CAS in asymptomatic patients. Second problem we see is the accuracy of our diagnostic methods. NASCET, ECST and ACAS were based on angiography, ACST on both, angiography and ultrasound. We have studied resected specimen on axial cuts and we have measured the steonsis diameter (ECST-like) and also p lanimetrically (F ig.X). T he r esults w ere c ompared w ith angiography, ultrasound and MRAG. In a region of 50% stenosis all techniques invariably underestimated actual stenosis. Angiography mostly so – underestimation was as much as 40% . The other techniques underestimated stenosis by some 10-20%. Recently CTAG is under study. The results pose some important questions – how much can we depend on large trials when the measurements are so much inac curate. However, there is nothing better available and indication criteria are generally accepted.. One serious doubt remains – same criteria used for CEA were taken over for CAS. This does not seem as scientifically sound approach. At least considering the results of some CAS studies. MM is reaching or even is higher than the recommended 6% MM. Additionally, in most studies asymptomatic and symptomatic patients are mixed and one can only wonder if the required MM of 3% in asymptomatic patients has been reached. The issue of CEA versus CAS has been addressed by 13 randomised trials. In the last three, EV A-3S, ICSS and CREST the results were in favor of surgery. In EVA-3S the MM rate in CEA was 3,9%, in CAS9,6% respectivelly. The trial has been prematurely terminated due to CEA superiority. ICSS and CREST trials results are summarised in Tab.2 and 3. As of recently these studies are the most important ones and should be followed when considering CEA and CAS. Certainly, CAS being such an a ttractive m ethod, w e c ould e xpect n ew s tudies a nd a lso development of CAS t echniques. Distal protection, common carotid balloon occlussion prior to the stent introduction, etc could improve the results and CAS in future and CAS could once again compete with 163
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CEA. Emotionally CAS is preffered by laymen and this fact should also be considered. We have compared our consecutive series of 1500 CEA with 600 CAS procedures which were done by our group. In our hands the results were statistically significantly better in CEA patients. We were unable to find any subgroup where CAS would be superior, nor contralateral occlussion, nor elderly patiens. We already have mentioned symptomatology. In summary, CEA is recently always the first line treatment, indications are set according to AHA g uidelines. Recently we never stent asymptomatic p atients. T he t echniques o f C EA a re w ell d escribed e.g.in Practical Handbook of Neurosurgery. CAS is reserved for special indications. All patients with restenosis are treated with CAS, as well as all carotid dissections. CAS is also used whenever we treat tandem lesion (e.g.bifurcation stenosis and cavernous ICA stenosis). Extremely rare p ostirradiotion s tenoses a re a lso t reated b y C AS. S ince w e perform all CEAs under general anesthesia we prefer CAS in patients with extremely high anesthesiological risks. Additionally , CAS is preferred in patients with specific anatomical conditions, e.g.high carotid bifurcation and in obese patients. Lastly, we prefer CAS in patients a fter the contralateral CEA where some peripheral nerve deficit (VII, XII) persists.
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b.
Carotid kinkink. Usual indications are repeated TIAs or minor stroke, sometimes head/neck position depend ent. Pathophysiologically TIAs are caused either by microemboli or by hemodynamic disturbances (simmilarly as the garden hose – whenever the hose is kinked, the flow stops, as soon as straightened, the flow is restored). The treatment is surgical restoration of laminar flow – exclusion of sharp bends. This can be achieved by resection of the kinked segment followed by either direct end-to-end suture or by reimplantation into the common CA. In many cases only the simple kink dissection, straitgtening and fixation by stitches to the surrounding structures is sufficient and dependable procedure.
c.
Carotid coiling. Indications are simmilar as in the kinks but coils are seldom symptomatic. Coil can be resected and shortened internal CA either sutured end-to-end or reimplanted into the common CA.
d.
Stump syndromes. Following internal CA thrombosis usually some sort of stump remains. Such a stump may easily be a source of emboli which by the way of natural (op hthalmic artery) or arteficial (EC -IC bypass) collaterals can embolise into the brain or retina. Common and external CA endarterectomy is performed and from within the vessel the internal CA orifice is closed using the continuous suture.
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e.
Carotid d esobliteration. In c ertain c ases d esobliteration o f t he thrombosed internal CA is possible and an attempt at desobliteration should b e m ade a t e very s tump s urgery. A s a n e lective p rocedure occluded internal CA is usual ly amenable to desobliteration in cases when retrograde flow in the internal CA is detectable as proximal as the region of foramen lacerum. I n cases where retrograde flow is detected as far as cavernous portion, desobliteration is sometimes successful. In cases with intracranial filling only , desobliteration is virtually impossible and should not be attempted on an elective basis.
f.
Carotid p seudoocclusion. In certain cases referred as carotid thrombosis some contrast media on angiography can be detected along the internal CA course. In these cases the stenosis is extremely tight and distal portion of the internal CA is collapsed, not thrombosed. Careful inspection of angiogramm is necessary. Simple CEA or stenting solves the problem. These findings should be coined 100% stenosis. Such cases are not any more seen since angiography lost its exclusive role and non-invas ive methods are currently used (CTA, MRA, ultrasound).
g.
External compression. Except for the postirradiation stenosis, which is caused by both, external compression and direct damage of the vessel wall, compression of the CA is extremely rarely seen in some neck soft tissue inflammatory processes. The treatment is either surgical artery deliberation or, more frequently, endovascular (in postirradiation stenosis).
3. Vertebral artery (VA). Due to its anatomical properties (2 VAs forming one basilar artery, i.e.the best possible collateral flow) very rarely indicated for reconstructive surgery. Its small diameter and thus much smaller inner surface also does not allow that easy emboli formation. a.
VA origin. Usual site of stenosis with possible emboli formation. Vertebro-basilar symptomatology, usually TIAs or minor strokes, are presenting s ymptoms. T ypical p rocedure i n t he t reatment o f V A stenosis is VA transposition – section at the origin from the subclavian artery and end-to-side anastomosis with the common carotid artery. This elegant surgery is recently replaced by interventional techniques, PTA or stent.
b.
VA in C6 through C1-2 . In t his s egment t ypical a therosclerotic stenoses are rarely seen. More frequently one may encounter kinkinks between t he t wo v ertebral f oramina o r a rterial c ompression b y osteophytes a t u ncovertebral r egion. I n t he f irst c ase a rtery deliberation a nd e ither k ink r esection o r k ink f ixation c an b e performed by lateral approach (Fig.5.). Resection of at least 2 adjacent
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anterior foraminal aspects is warranted. In the external compression osteophytes resection via the lateral or anterior approach is possible. The indications are rare. c.
Lesions above the C1 . In this segment of the V A, up to the V A junction, regular atherosclerotic stenoses are frequently seen. Symptomatic ones can be treated either by interventional techniques or using some form of bypass (common carotid-vertebral artery , occipital artery – PICA (Fig.6.), etc.). Very rare bow-hunter syndrome can be treated ether by VA deliberation or by C1-2 fixation.
4. Cavernous portion of CA. Following the CA bifurcation the second most frequent site of stenoses. These may either be separate or, rather frequently, are seen as a tandem lesions with CA bifurcation stenosis. The indications for treatment should be the same as for the ordinary CA stenosis. In this regions surgeries for ischemic symptoms are not performed. The stenosis is however easily m anaged v ia e ndovascular a pproach. B oth, s imple P TA, o r s tent introduction can be performed. The fate of the tandem lesions after the CEA remains to be studied. However , tandem lesion is recently one of the best indications for endovascular treatment. Both, bifurcation and tandem stenosis are easily managed at one procedure. 5. Intracranial vessels. Prior to any intracranial procedure for ischemic reasons some form of functional testing is necessary. The most frequently employed protocols call for cerebrovascular reserve capacity (CVRC) measurements. Impaired or lost CVRC can be detected by studies using XeCT CBF, SPECT, PET, perfusion CT, even TCD. Following the EC-IC Bypass Study all active measures for cerebral ischemia are individual and patient individualised.
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a.
EC-IC bypass. Very s imple, e legant a nd l ogical p rocedure w here branch of the superficial temporal artery is end-to-side anastomosed to one of the distal branches of the middle cerebral artery (Fig.8.). Thus the hemisphere can get some 18-20 ml blood per minute. After the publication of EC -IC Bypass Study the procedure was nearly abandoned. Several groups recently study the procedure in the light of the CVRC testing. In the past several years we have been indicating patients w ith p artial n eurologic d eficit, n one o r b order z one hypodensity on CT and impaired CVRC as determined on baseline and Acetazolamide challenged SPECT. The results are very safisfactory from both clinical and postop CVRC investigations aspects. Probably the time is ripe for another, more detailed randomised study.
b.
EC-IC bypass variations. There were many variations described. Technically almost any cerebral artery can be supplied via some form
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of arteficial anastomosis. For example, occipital artery – PICA bypass procedure is used, superficial temporal artery can be anastomosed to superior cerebral or superior cerebellar artery, both anterior cerebral arteries side-to-side anastomosis is described, etc. Sometimes highflow bypasses are employed using vein or arterial grafts (Fig.8.). These may e ither b e l ong e xtra-intracranial ( common C A t o i ntracranial internal CA or to proximal middle cerebral artery branch) or short intra-intracranial (short graft may bypass the cavernous portion of the internal CA). In general, possibilities and techniques (e.g.laser assisted suture) a re n umerous, i ndications ra re. M ost c ommonly t hese procedures a re u sed i n t he t reatment o f s kull ba se t umors a nd i n inaccessble aneurysms. In the treatment of cerebral ischemia of the atherosclerotic origin the indications are usually infrequent at best. c.
Direct procedures. Few middle cerebral artery embolectomies were published. T hese p rocedures m ay b e p erformed o n a n e mergency basis, on e c an h ardly i magine d irect s urgery o n a n el ective b asis. Endarterectomies a re no t u sed. P laques c ausing s tenoses o f intracranial CA or M1 segment are solved interventionally. Balloon dilatation and stent introduction is simmilar as in the treatment of vasospasms. Soft intracranial stents are now available and these are the f irst c hoice t reatment i n i ntracranial v essels s tenoses. T he indications for all stenoses from foramen lacerum distally are not yet clearly determined and each patient should be evaluated individually (Fig.9.). Emergency procedures (trombolysis) will be discussed in the timing section of this article.
6. Non-atherosclerotic conditions. There are numerous diseases and conditions causing cerebral ischemia. Only those more frequently encountered by neurosurgeons will be briefly mentioned. a.
Moya-moya disease. During the course of the disease major cerebral arteries at the brain get occluded and typical pathological collateral network a ppears (Fig.10.). Clinical symptoms are either those of cerebral ischemia or those of intracerebral/subarachnoid hemorrhage. The treatment of ischemic symptoms, especially in children are various forms of r evascularisation. M ost c ommonly u sed p rocedure i s encephalo-duro-arterio-myosynangiosis.
b.
Fibromuscular dysplasia. Magistral vessels, predominantly CAs at the neck region are affected. Angiographically „string of pearls“ is a typical sign. The treatment is medical, in some cases endovascular balloon dilatation and/or stenting can be employed.
c.
Arterial dissection, aneurysms and pseudoaneurysms. Symptoms are TIAs o r c ompleted s troke, u sually a m inor o ne. I n c ases w here
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anticoagulation t reatment f ails, e ndovascular p rocedures a nd revascualarisation ( EC-IC b ypass) s hould b e c onsidered o n a n individual basis. Aneurysms and pseudoaneurysms which usually are seen at the internal CA bellow the skull base are the results of arterial dissection. They are best treated by stenting (Fig.11.). Direct surgery with a n a ttempt a t d irect ve ssel r econstruction c an b e ex tremely hazardous and difficult. These lesions tend to extend up to the point of CA entry into the foramen lacerum. d.
Other reasons for revascularisation procedures. Such procedures are part of the regular treatment of skull base tumors, cavernous aneurysms, etc. They are mentioned in an appropriate section and the detailed description is beyond the possibilities of this article. Only one general remark. In every case, where the sacrifice of the major artery may b e n ecessary d uring t he s urgery, b alloon oc clusion t est wi th clinical or electrophysiological evaluation should be part of the routine presurgical work-up.
7. Emergency revascularisations. The outcome of ischemic event d epends on time and depth of the ischemic event. In its early stages the clinical symptoms may be reversible by the blood flow restoration. The blood flow can be restored either by systemic trombolysis (rTPA, urokinase) or by interventional (i.a.thrombolysis, m echanic t hrombectomy) o r r arely b y s urgical m eans (thromboendarterectomy). According to NIH protocol, intravenous trombolysis can be used up to 4,5 hours after the symptom onset and up to hypodensity smaller than 30% in one of the three major arterial territories. Intraarterial thrombolysis o r o ther m easures ( e.g.mechanical t hrombolysis) h ave m ore favourable time window – up to six hours for thrombolysis and up to 8 hours for mechanical trombus retrieval (Fig.12.). These conditions are very strict and time-wise difficult to fulfill in more than a certain fraction of patients. In USA some 10 % a nd i n E urope s ome 2 -5% of s troke p atients a re t reated b y emergency blood-flow restoration. However, since the stroke is getting more attention in professional and laymen public, the situation is improving. Also, the time scale for intraarterial procedures is much more suitable for health care organisation and many more patiens can enjoy the benefit of emergency treatment in near future. The above mentioned timing does not apply to basilar thrombosis. In a condition with nearly 100% mortality any treatment yelding better results is fully justifiable (Fig.13.). According to our experiences with em ergency c arotid d esobliteration, t he m ost i mportant f actor i s t he clinical d ynamics o f t he d isease. I n p atients w ith a brupt o nset a nd d eep neurological deficit since the very beginning, little can be achieved by active measures. However, in patients with dynamic deficit – stroke in evolution – the final r esults w ere i n 90 % o f o ur p atients e xcellent de spite t he f act, t hat immediatelly prior to surgery their clinical status was same deep and complete deficit as in the fixed defi cit group. P atients with fluctuat ing deficit ar e the 168
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best candidates for emergency revascularisation. The timing depends on their clinical condition, once their neurological deficit becomes stable and complete, there ma y b e a dditional 3 -4 h ours f or e ither su rgery o r t rombolysis ( NIH protocol). In patients with neck region CA thrombosis we always prefer surgery which is faster and easier than trombolysis. We also believe that the clot in this region is too big for the trombolytics and there is the danger of embolisation of the fragmented clot remnants into the cerebral circulation. Just opposite, embolic or thrombotic occlus ion of intracranial vessel is now exclusively managed by endovascular means. Possible surgical procedure is longer, more difficult, there is the retraction of the already damaged brain, etc. Recently, in our hands the preffered therapeutical modality is mechanical trombus retrieval. 8. Ischemic mass-lesions. Repeatedly publications on various decompressive procedures in supratentorial ischemic lesions appear in the literature. Considering the debilitating morbidity following the middle cerebral artery infarction t hese s urgeries d o n ot s eem t o a ttract m uch a ppraisal o f t he neurosurgical community. We consider decompression in younger patiens, in non-dominant hemisphere and preferebly with incomplete deficit and CT hypodensity only outside the basal ganglia. Patients exhibiting clinical masslesion caused by the malacia in anterior or posterior cerebral artery territory are extremely rare. Such patients should be evaluated individually . On the other hand, cerebellar infarction with mass-lesion effect can be considered the same neurosurgical emergency as an epidural hematoma. Depending on the patients status and disease dynamics there are three surgical options: 1. Ventricular drainage, 2. Bony decompression of the posterior fossa along with the foramen magnum opening, and 3. Malatic tissue resection. These infarction are typically in the distribution of either PICA (Fig.14) or superior cerebellar artery. In cases where the origins of these arteries are occluded, brainstem s igns a ppear i mmediatelly s ince t he o nset a nd s urgery i s n ot warranted (Fig.15.). In cases, where brainstem signs appear later being caused by t he m alatic t issue p ressure, de compression i s t o b e p erformed o n a n emergency basis. Cave: rapid increase of lesion volume can also be caused by hemorrhagic transformation of theischemic lesion.
Future questions and direction There are several trends in neurosurgery for cerebral ischemia. First, the shift towards non-invasive diagnostics along with empl oyment of various functional tests (TCD, SPECT, PET, EEG, etc). Modern investigation allows us to determine the ischemic status more individually and custom tailor the procedure for each individual patient. Second, recent rapid development of interventional neur oradiology is taking over and allows us to treat even the patients who are not fit enough to undergo open surgery. These techniques also allow to treat lesions previously deemed untreatable
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or inaccessible. Third, in near future the research development should allo w us to open t he therapeutic window (brain protection as an stroke on-site measure) more widely and thus trombolysis will be accessible to more patients. Comparison o f c erebral i schemic s troke w ith m yocardial i nfarction i s o bvious. Etiology is the same atherosclerosis, resulting tissue ischemia also, final necrosis too. In this comparison all the advantages are at the side of the heart – at the end the resulting necrosis in the myocardial infarction affects the muscle, which additionally survives far longer ischemic period in the ischemic stroke the affected tissue is the brain. The result of survived myocardial infarction is fully capable person with all capacities retained. The result in cer ebral ischemic stroke is usually permanent disability which dramatically affects the quality of life. We should push our research and clinical capacities to catch up with the treatment of the diseased heart. However, we shall never be able to get even. At the very end, the heart damaged by ischemic heart disease can be replaced by transplantation, the brain damaged by ischemic brain disease is causing dementia and brain trnasplantation is nonsence.
Highlights and conclusions Cerebral i schemia i s t he t hird l argest m edical m arket. R ecent n eurosurgical involvement in this area is insufficient. CEAs are taken over by vascular and general surgeons, E C-IC b ypasses a re su rviving a t s everal i nstitutions o nly, t rombolytic treatment is studied and propagated by neurologists, many delicate procedures are taken over by interventional radiologists. However, the target system is always the brain, the domain of neurosurgeons who are best suited to treat this system actively . Neurosurgeons are also the only ones capable of treatment related complications management. It is the strong authors convinction that young generation of neurosurgeons should get more involved in the field of cerebral ischemia. Supported by grants IGA 9640-4
Recommended reading AHA (http://circ.ahajournals.org/cgi/content/full/97/5/501). Beneš V, Urbánková E: Alternative M anagement of Carotid Kinkink. Z bl.Neurochir, 1989, 50:97-98. Beneš V, Steindler J: Emergency internal carotid artery desobliteration in patients with severe neurological deficit. 11th Intl Congress of Neurological Surgery. Monduzzi Editore, Bologna 1997. Pp.1059-1063.
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Beneš V , N etuka D , M andys V , V rabec M , M ohapl M , B eneš V Jr , K ramář F: Comparison between degree of carotid stenosis observed at angiography and in histological examination. Acta Neurochir (Wien). 2004 Jul;146(7):671-7. Netuka D, B eneš V, M andys V, H lásenská J , B urkert J , B eneš V J r.: A ccuracy o f angiography and Doppler ultrasonography in the detection of carotid stenosis: a histopathological study of 123 cases. Acta Neurochir (Wien)2006,148:511-520. Beneš V: Stenotic and occlusive vascular disease. In: European Manual of Medicine. Neurosurgery. Eds. Arnold W, Ganzer U. Eds Neurosurgery: Lumenta CB, Di Rocco C, Haase J, Mooij JJA. Springer 2010. Pp.210-221. Beneš V: Carotid endarterectomy. In: Sindou M: Practical Handbook of Neurosurgery, Vol.1. Springer Wien New York 2009:337-353. The EC/IC Bypass Study Group: Failure of extracranial-intracranial arterial bypass to reduce the risk of ischemic stroke. Results of an international randomized trial. N Engl J Med 1985, 313:191-200. Mayberg MR, W ilson SE, Yatsu F, Weiss DG, M essina L, Hershey LA, Colling C, Eskridge J, Deykin D, Winn HR, for the Veterans Affairs Cooperative Studies Program 309 Trialist Group. Carotid endarterectomy and prevention of cerebral ischemia in symptomatic carotid stenosis. JAMA. 1991;266:3289–3294. Mayo Asymptomatic Carotid Endarterectomy Study Group. Results of a randomized controlled trial of carotid endarterectomy for asymptomatic carotid stenosis. Mayo Clin Proc. 1992;67:513–518. Schmiedek P, Piepgras A, Leisinger G et al: Improvement of cerebrovascular resere capacity by EC -IC arterial bypass surgery in patients with ICA occlusion and hemodynamic cerebral ischemia. J Neurosurg 1994, 81:236-244. Sundt TM Jr: Occlusive Cerebrovascular Disease. WB Saunders Comp, Philadelphia 1987. Warlow CP. Symptomatic patients: the European Carotid Surgery Trial (ECST). J Mal Vasc. 1993;18:198–201. NASCET North American Symptomatic Carotid Endarterectomy Trial Collaborators: Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med 1991; 325: 445-453. Barnett HJ, Taylor DW, Eliasziw M, Fox AJ, Ferguson GG, Haynes RB, Rankin RN, Clagett GP, Hachinski VC, Sackett DL, Thorpe KE, Meldrum HE, for the North American Symptomatic Carotid Endarterectomy Trial Collaborators. B enefit o f c arotid e ndarterectomy i n p atients w ith s ymptomatic
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moderate or severe stenosis. N Engl J Med 1998; 339: 1415-1425. ECST European Carotid Surgery T rialists´ Collaborative Group. Randomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST). Lancet 1998; 351: 1379-1387. ACAS Executive C ommittee f or t he A symptomatic C arotid A therosclerosis S tudy. Endarterectomy for asymptomatic carotid stenosis. JAMA 1995; 273: 1421-1428. ACST Asymptomatic C arotid S urgery T rial ( ACST) C ollaborative G roup. P revention o f disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: randomised controlled trial. Lancet 2004; 363: 14911502. CaRESS CaRESS S teering C ommittee C arotid R evascularization U sing E ndarterectomy o r Stenting Systems (CaRESS) phase I clinical trial: 1-year results. J V asc Surg 2005 ; 42(2): 213-9. CAVATAS Endovascular v ersus s urgical t reatment i n p atients w ith c arotid s tenosis i n t he Carotid a nd V ertebral A rtery T ransluminal A ngioplasty S tudy ( CAVATAS): a randomised trial. Lancet 2001; 357: 1729-37. SAPPHIRE Yadav JS, Wholey MH, Kuntz RE, Fayad P, Katzen BT, Mishkel GJ, Bajwa TK, Whitlow P, Strickman NE, Jaff MR, Popma JJ, Snead DB, Cutlip DE, Firth BG, Ouriel K. Stenting and A ngioplasty w ith P rotection i n P atients a t H igh R isk f or E ndarterectomy Investigators. Protected carotid-artery stenting versus endarterectomy in high-risk patients. N Engl J Med 2004; 351(15): 1493-501. SPACE SPACE Collaborative Group, Ringleb P A, Allenberg J, Brückmann H, Eckstein HH , Fraedrich G, Hartmann M, Hennerici M, Jansen O, Klein G, Kunze A, Marx P, Niederkorn K, Schmiedt W, Solymosi L, Stingele R, Zeumer H, Hacke W. 30 day results from the SPACE trial of stent-protected angioplasty versus carotid endarterectomy in symptomatic patients: a randomised non-inferiority trial. Lancet 2006; 368: 123947. EVA 3s 172
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Mas JL, Chatellier G, Beyssen B, Branchereau A , Moulin T, Becquemin JP, Larrue V, Li`evre M, Leys D, Bonneville JF, Watelet J, Pruvo JP, Albucher JF, Viguier A, Piquet P, Garnier P, Viader F, Touzé E, Giroud M, Hosseini H, Pillet JC, F avrole P, Neau JP, Ducrocq X; EVA-3S Investigators. Endarterectomy versus stenting in patients with symptomatic severe carotid stenosis. N Engl J Med 2006; 355(16): 1660-71. Quoting "Vladimir Beneš" : CREST Mantese VA, Timaran CH, Chiu D, Begg RJ, Brott TG; CREST Investigators. The Carotid Revascularization E ndarterectomy v ersus S tenting Trial ( CREST): s tenting v ersus carotid endarterectomy for carotid disease.Stroke. 2010 Oct;41(10 Suppl):S31-4. ICSS International Carotid Stenting Study investigators, Ederle J, Dobson J, Featherstone RL, Bonati LH, van der Worp HB, de Borst GJ, Lo TH, Gaines P, Dorman PJ, Macdonald S, Lyrer PA, Hendriks JM, McCollum C, Nederkoorn PJ, Brown MM. Carotid artery stenting c ompared w ith en darterectomy i n p atients w ith s ymptomatic c arotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial. Lancet. 2010 Mar 20;375(9719):985-97. Epub 2010 Feb 25.
Fig.X
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Tab.2
Tab.3
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PLACE, ROLE AND TECHNIQUES FOR CEREBRAL BY-PASS SURGERY Luca Regli, Professor and Chairman, Rudolf Magnus Institute of Neurosciences, Department of Neurosurgery , University Medical Center Utrecht, NL
Background The possibility of providing extra blood flow to the brain exists since 1967 when the first STA-MCA bypass (superficial temporal artery-middle cerebral artery bypass) was done by M.G. Yasargil. Cerebral bypass surgery is a safe and elegant procedure that allows to r evascularize a rterial t erritories o f t he b rain. T he p urpose o f t his presentation is to review the current status of cerebral revascularization and evaluate the important steps for achieving the ideal bypass: 1. Indication, 2. Technique, and 3. Future developments (Neurosurg Focus. 2008;24(2):E2). Bypass surgery comes in two flavours: a. flow augmentation for occlusive cerebrovascular diseases and b. flow preservation for parent vessel occlusion in aneurysms and tumours. Literature review: Flow Augmentation: The results of an international randomized multicenter trial analysing the benefit of EC-IC bypass in preventing future stroke in patients with carotid artery or middle cerebral artery occlusion/stenosis where publis hed in 1985 (N Engl J Med 1985;313:1191-1200). Among 1377 randomized patients the study failed to show any benefit from EC-IC bypass. The t rial ha s b een l argely c ommented a nd c riticized f or n ot i dentifying a nd separately a nalyzing p atients w ith a nd w ithout h emodynamic c ompromise (cerebrovascular reserve deficit). Now a days modern neuroimaging techniques (PET, CT-xenon, CT -perfusion, MR-perfusion) make it possible to evaluate cerebral hemodynamics in patients w ith occlusive cerebrovascular d iseases. Prospective natural history studies have demonstrated the increased risk of subsequent stroke in patients with symptomatic carotid artery occlusion and increased oxygen extraction fraction on PET ( OEF = exhausted cerebrovascular reserve = misery perfusion). The 2-year ipsilateral stroke rate ranged from 26% to 57% and compared to stroke rates of 5% to 15% in patients with normal OEF (absolute risk reduction of 21% to 41% and relative risk reduction of 75% to 80%).(JAMA. 1998; 280:10551060; Radiology. 1999; 212:499-506; J Nucl Med. 1999; 40:1992-1998). Flow Preservation: Although t he p referred t reatment o ption o f a neurysms i s p rimary a neurysm exclusion with direct reconstruction of the parent artery ( coils or clips), some highly complex a neurysms c an no t b e r econstructed, b ecause of a l arge, c alcified o r atherosclerotic base, branches originating from the dome or a fusiform shape. One treatment option in these difficult aneurysms is parent artery sacrifice by trapping or proximal occlusion. The use of cerebral revascularization procedures in preventing ischemic neurological deficits in acute parent vessel sacrifice is well established 176
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(Neurosurgery. 2008; 63: 12-20; Neurosurgery . 2008 ;62(6 Suppl 3):1411-8; J Neurosurg. 1995 ;83:806-11; Neurosurgery. 1996 ;38:83-92 ). To predict tolerance for acute vessel sacrifice results from balloon test occlusion are the most reliable (AJNR. 2005; 26: 2602-9; Neurosurgery 2002; 50: 996-1004). Surgical Technique The French physician Carrel developed and published in 1902 the first arterial endto-side anastomosis utilizing fine suture material. The development of neurosurgical vascular bypass techniques made a leap in the 60’s , when the mer ging with the development in surgical magnification led to rapid growth of cerebral microvascular surgery. Since then, to construct a microvascular anastomosis, temporary occlusion of the recipient vessel and end-to-side attachment of a donor vessel with interrupted or continuous microsutures is still the standard technique in neurosurgery. Further more it is important to understand the amount of flow that the bypass is expected t o d eliver. T his a llows c ustomizing t he b ypass i n o rder t o m atch t he amount of flow needed to replace the sacrificed vessel. By choosing the adequate recipient artery (internal carotid artery, proximal or distal branches of the MCA, the ACA or the PCA) and donor vessel (STA, occipital artery, internal or external cervical carotid artery, a venous or arterial interposition graft) one can construct a high flow (>80ml/min), intermediate-flow (30-80ml/min) or low-flow (220/120 mmHg) on repeated measurements, or with severe cardiac failure, aortic dissection, or hypertensive encephalopathy
•
low b lood p ressure s econdary t o h ypovolaemia o r a ssociated w ith neurological deterioration in acute stroke should be treated with volume expanders
•
treatment of serum glucose levels >180 mg/dl (>10 mmol/l) with insulin titration is recommended
•
presence o f p yrexia ( temperature > 37.5°C) s hould p rompt a s earch f or concurrent infection, treatment with paracetamol and fanning is recommended.
Treatment of an brain oedema and elevated intracranial pressure Medical t herapy b egins f rom h ead p ositioning a t a n e levation o f up t o 3 0°, avoidance of noxious stimuli, pain relief, appropriate oxygenation and normalizing body temperature. Cerebral perfusion pressure should be kept above 70 mmHg. Intravenous glycerol (4 x 250 ml of 10% glycerol over 30–60 minutes) or mannitol (25–50 g every 3–6 hours) is first line medical treatment if clinical or radiological signs of space-occupying oedema occur. Thiopental given as a bolus can quickly and significantly reduce ICP, and can be used to treat acute crises. Decompressive surgery is indicated in cases of malignant MCA infarction. Inclusion criteria for combined pooled analysis of 93 patients included in the DECIMAL, DESTINY and HAMLET trials were age 18-60 years, NIHSSS >15, decrease in level of consciousness to a score of 1 or greater on item 1a of the NIHSS, infarct signs on CT of 50 % or more of the MCA territory or >145 cm³ on DWI, and inclusion
