An Integrated Approach to Balance Assessment • Can we get better performance out of our diagnostic batteries with a systems approach? pp • VIIIth Nerve syndromes (al a Zapala, et al.) • Compensation Status • Links to Functional Status

Approach • Hard to study labyrinth directly • Group by test results – Look for trends in • Chief Chi f complaint l i • Medical diagnosis • Functional performance: – Computerized Dynamic Posturography Sensory Organization Test

– Self perceived handicap • DHI scores Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Anatomical Units in the Inner Ear • • • • •

Bony shell considerations Membrane compartments Sensory epithelium (hair cell structures) Arterial supply Innervation pattern

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Semicircular Canals

Image: Jay W. McLaren, Ph.D.

Sensory Epithelium • Vestibular: – Three Crista • Horizontal • Anterior/superior • Posterior/inferior P t i /i f i

– Maculae • Saccule • Utricle

• Auditory: – Organ of Corti Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Maculea: Saccule • Action: – Vertical and anterior /posterior (A/P) translational movements – Acceleration

Image: Jay W. McLaren, Ph.D.

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Saccule: Primarily Vertical Translations

Maculae: Utricle • Action: – Lateral translations – Acceleration and static i head h d tilt il

Image: Jay W. McLaren, Ph.D.

Utricle Encoding: Static Tilt and Acceleration

www.utdallas.edu/~tres/integ/ sen5/sense_5.html Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

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“On Top of a Long Stalk”

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Labyrinthine Arterial Supply

Image: David Dickman, Washington U.

Disrupting the Blood Supply • Labyrinthine artery = Catastrophic loss of Vestibulocochlear function

• Common cochlear a. = Loss of hearing, saccule (?) and posterior canal (?) function

• Anterior vestibular a.

= Loss of utricle?, Anterior and horizontal canal function

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Branches of CN VIII • Auditory • Vestibular – Superior – Inferior

Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Vestibular Nerves • Superior nerve – Horizontal Crista – Anterior Crista – Utricle – Saccule (Voit’s)

Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Vestibular Nerves • Inferior nerve – Posterior Crista • Singular nerve – Saccule S l • Saccular nerve – Olivary-cochlear bundle (cochlear efferent supply) Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

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Major Nerves in the IAC

• Facial N. - Superior & Anterior • Cochlear N. - Inferior & Anterior • Superior Vestibular N. • Inferior Vestibular N.

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Nerve Based Syndromes • Superior nerve (LSU) – Loss of superior and horizontal canal function – Loss of utricular function

• Inferior nerve – Loss of posterior canal function – Loss of Saccule?

• Cochlear nerve • Facial nerve Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Potential Syndrome Groupings • Membrane based... – – – –

Pars superior. Endolymphatic sac. Saccule. S ccu e. Cochlea.

• Vascular based...

• Nerve based... – – – – –

LSU; Saccule, os e o ccanal.. Posterior Cochlea. Facial.

• Bony dehiscence.

– Pars superior. • LSU.

– Pars inferior. – Pars inferior + PSSC.

– Horizontal canal. – Superior canal. – Posterior canal.

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Zapala, Pratt & Schaedler • Consecutive series of 1578 patients assessed for potential vestibular disorders – Selected subset with unilateral vestibulopathy who received comprehensive battery – No complicating medical conditions • (No concurrent middle ear, nervous system, musculoskeletal disease or other factor)

• Grouped cases based on audiometric and vestibular assessment results Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Vestibular Function Tests • Standard ENG/VNG – Caloric test – Positional and positioning studies – Ocular motor inventory

• • • •

Rotary chair Computerized Dynamic Posturography (CDP) Vestibular Evoked Myogenic potentials (VEMPs) Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Four Site of Lesion Tests • Audiological evaluation – Organ of Corti and cochlear nerve

• Bilateral, bi-thermal caloric test – Horizontal semicircular canal and superior vestibular nerve

• Vestibular evoked myogenic potentials (VEMPs) – Saccule and inferior nerve

• Dix - Hallpike test – Posterior semicircular canal Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

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Audiologic Test by Eighth Nerve Branch Test

Nerve

Audiogram

Cochlear Branch

VEMP

Inferior Vestibular Nerve Branch

Caloric Response

Superior Vestibular Nerve Branch Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Defined Syndromes Syndrome

Cochlear N. (Audio)

Superior Inferior Cochlear

Normal Normal Abnormal

Superior Vestib N. (Caloric) Abnormal Normal Normal

Inferior Vestib N. (VEMP) Normal Abnormal Normal

Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Defined Syndromes Syndrome

Cochlear N. (Audio)

Superior Vest. N. (Caloric)

Inferior Vest. N. (VEMP)

Posterior Basement

Normal Abnormal

Abnormal Normal

Abnormal Abnormal

Split

Abnormal

Abnormal

Normal

Global

Abnormal

Abnormal

Abnormal

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Functional Results Syndrome

Hearing Involvem ent

Caloric Normal

VEMP Normal

BPPV

Vertigo

CDP/ SOT

DHI

Superior

No

No

Yes

22%

38%

64

45

Split

Yes

No

Yes

25%

69%

62

40

Posterior/ Cochlear

Yes

No

No

5%

45%

57

41

Posterior

No

No

No

0%

45%

58

37

Basement

Yes

Yes

No

0%

29%

54

39

Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Prevalence of Vestibular Schwannoma • 62 cases on record in the clinic during the analysis period – Most were being followed either without treatment or post treatment

• 16 Had received vestibular and Audiological studies including VEMPs – “Discovered” tumors Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Tumors > 8.5 mm

Tumors By Syndrome

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Summary • Syndromes largely follow innervation and blood supply

Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Summary • Syndromes involving … – The horizontal canal (superior nerve distribution or anterior vestibular artery) • Higher % experience vertigo • Higher % experience BPPV • Greater perception of handicap

– The saccule (inferior nerve distribution) • Less likely to complain of vertigo • Less secondary BPPV • Poorer postural stability (lower SOT scores)

We could not demonstrate this without VEMPS! Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Summary • How good is history? – Presenting complaint of “vertigo” is insufficient as a marker for vestibulopathy p y

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Value of the VEMP • Without a VEMP, cannot discern between a split syndrome (cochlear and superior nerve involvement) and a global syndrome. –T Tumor prevalence l in i the th combined bi d split lit + global l b l group was 9% – Likelihood ratio dropped to 5.4

• POINT: – IF Audiological and Caloric are abnormal, run a VEMP Zapala, Pratt, Schaedler-Mayo ClinicJacksonville

Assessing the Status of Compensation • • • •

Calorics? Posturography? Head Shake? Hyperventilation Test?

The Team Approach to Diagnostics • • • • •

Physician Radiology/Imaging Physical Therapy Audiology Nursing

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Thank you for your kind attention!

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