An Integrated Approach to Balance Assessment. Approach. Anatomical Units in the Inner Ear

Transcription

1 An Integrated Approach to Balance Assessment Can we get better performance out of our diagnostic batteries with a systems approach? 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 complaint Medical diagnosis Functional performance: Computerized Dynamic Posturography Sensory Organization Test Self perceived handicap DHI scores Anatomical Units in the Inner Ear Bony shell considerations Membrane compartments Sensory epithelium (hair cell structures) Arterial supply Innervation pattern 1

2 Semicircular Canals Image: Jay W. McLaren, Ph.D. Sensory Epithelium Vestibular: Three Crista Horizontal Anterior/superior Posterior/inferior i Maculae Saccule Utricle Auditory: Organ of Corti Action: Vertical and anterior /posterior (A/P) translational movements Acceleration Maculea: Saccule Image: Jay W. McLaren, Ph.D. 2

3 Saccule: Primarily Vertical Translations Action: Lateral translations Acceleration and static head tilt Maculae: Utricle Image: Jay W. McLaren, Ph.D. Utricle Encoding: Static Tilt and Acceleration sen5/sense_5.html 3

4 On Top of a Long Stalk Labyrinthine Arterial Supply Image: David Dickman, Washington U. Disrupting the Blood Supply Labyrinthine artery Common cochlear a. Anterior vestibular a. = Catastrophic loss of Vestibulocochlear function = Loss of hearing, saccule (?) and posterior canal (?) function = Loss of utricle?, Anterior and horizontal canal function 4

5 Branches of CN VIII Auditory Vestibular Superior Inferior Vestibular Nerves Superior nerve Horizontal Crista Anterior Crista Utricle Saccule (Voit s) Inferior nerve Posterior Crista Singular nerve Saccule Saccular nerve Olivary-cochlear bundle (cochlear efferent supply) Vestibular Nerves 5

6 Major Nerves in the IAC Facial N. - Superior & Anterior Cochlear N. - Inferior & Anterior Superior Vestibular N. Inferior Vestibular N. <ANT IN NF> 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 Potential Syndrome Groupings Membrane based... Pars superior. Endolymphatic sac. Saccule. Cochlea. Vascular based... Pars superior. LSU. Pars inferior. Pars inferior + PSSC. Nerve based... LSU; Saccule, Posterior o canal. Cochlea. Facial. Bony dehiscence. Horizontal canal. Superior canal. Posterior canal. 6

7 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 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) 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 7

8 Test Audiologic Test by Eighth Nerve Branch Nerve Audiogram VEMP Caloric Response Cochlear Branch Inferior Vestibular Nerve Branch Superior Vestibular Nerve Branch Defined Syndromes Syndrome Cochlear N. (Audio) Superior Vestib N. (Caloric) Inferior Vestib N. (VEMP) Superior Normal Abnormal Normal Inferior Normal Normal Abnormal Cochlear Abnormal Normal Normal Defined Syndromes Syndrome Cochlear N. (Audio) Superior Vest. N. (Caloric) Inferior Vest. N. (VEMP) Posterior Normal Abnormal Abnormal Basement Abnormal Normal Abnormal Split Abnormal Abnormal Normal Global Abnormal Abnormal Abnormal 8

9 Syndrome Hearing Involvem ent Functional Results Caloric Normal VEMP Normal BPPV Vertigo CDP/ SOT Superior No No Yes 22% 38% DHI Split Yes No Yes 25% 69% Posterior/ Yes No No 5% 45% Cochlear Posterior No No No 0% 45% Basement Yes Yes No 0% 29% 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 Tumors > 8.5 mm Tumors By Syndrome 9

10 Summary Syndromes largely follow innervation and blood supply 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! Summary How good is history? Presenting complaint of vertigo is insufficient as a marker for vestibulopathy 10

11 Value of the VEMP Without a VEMP, cannot discern between a split syndrome (cochlear and superior nerve involvement) and a global syndrome. Tumor prevalence in the combined split + global l group was 9% Likelihood ratio dropped to 5.4 POINT: IF Audiological and Caloric are abnormal, run a VEMP Assessing the Status of Compensation Calorics? Posturography? Head Shake? Hyperventilation Test? The Team Approach to Diagnostics Physician Radiology/Imaging Physical Therapy Physical Therapy Audiology Nursing 11

12 Thank you for your kind attention! 12