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Investigating a Dizzy Patient
- 1. MOHAMMAD, S ASGHAR THE EAR INSTITUTE AUDIOLOGY CLINIC, SCARBOROUGH GENERAL HOSPITAL, SCARBOROUGH, ON Investigating a Dizzy patient Dizzy Battery at a Glance
- 2. Primary role of Ear The primary role of the ear (the inner ear) is equilibrium. This statement is based on the phylogenic development of the inner ear. Phylogeny is the sequence of the embryological development of a species. The earlier in the development, the more primitive or necessary is its function. The labyrinth portion (vestibular) of the inner ear precedes the development of the cochlea.
- 3. Importance of Vestibular system Could a species survive hard of hearing or even deafness? Sure, but the species probably would have evolved making better use of its remaining sensory modalities; i.e. peripheral vision, etc. However, could a species survive without the ability to stand, coordinate eye and head movement, or navigate through space? No. The species obviously could not survive.
- 4. Why Get Vestibular Tests? Recent studies have documented that vestibular tests are more accurate than clinical examination in identifying inner ear disorders (Gordon et al, 1996). Hearing pathway tests (audiometry, auditory brainstem response, electrocochleography) can also be used for the same purpose, and are frequently combined with vestibular tests.
- 5. Why Get Vestibular Tests? (conti) Vestibular tests can help determine if more expensive tests, such as magnetic resonance imaging (MRI), are needed. Recent studies (Levy and Arts, 1996) have shown that vestibular testing is much more accurate than clinical symptoms in predicting whether neuro-imaging tests will be abnormal. Vestibular tests can also document objectively vestibular conditions such as benign paroxysmal positional vertigo (BPPV), and perilymph fistula, which commonly occur after head injury; and bilateral vestibular ototoxicity, which commonly is a side effect of medication.
- 7. Anatomy of the vestibular system
- 8. Inner Ear: Bony and Membranous Labyrinths Medial View
- 9. Anatomy of Vestibular System
- 10. Blood supply of Inner Ear
- 11. Irrigation Parallels Innervation Blood supply Innervation Basilar A VIIIth N AICA Labyrinthine A Common Cochlear Artery Main Cochlear Artery Cochlea Auditory Nerve Vestibulo Cochlear artery Vestibular N Post Vest A Post SCC Ampulla Inferior division Majority of Saccule Ant Vestibular A Anterior SCC Ampulla Superior Division Horizontal SCC Ampulla Utricle Minority of Saccule
- 14. Vestibular system: central connections
- 15. Central connections. (Important for rehab) First order afferents : These are bipolar cells located deep in the internal auditory meatus. In children the number of cells is around 80000. In elderly it is 11000. So you can Imagine the incidence of imbalance in elderly
- 16. Anatomic and Basic Medical considerations: Multiple sensory inputs contribute to balance function. Vestibular end organ Visual system And Somatosensory system/proprioceptive system The information is integrated at the level of brainstem and cerebellum with influence from cerebral cortex including frontal, parietal and occipital lobes. The integrated input information results in various motor and perceptual outputs.
- 17. Balance system
- 18. Visual System Sensory Motor Environmental Interaction Compare, Select and Combine Senses Select and Adjust Muscle Contractile Patterns Generation of Body Movement Vestibular System Somato- Sensation Ankle Muscles Trunk Muscles Thigh Muscles Initiate Automatic/ Voluntary Movements Determine Body Position www.natus.com Dynamic Equilibrium (The concept) Central integration
- 19. • Reflexes • Automatic and adaptive postural responses • Anticipatory postural set • Voluntary movements Ankle Muscles Generation of Body Movement Trunk Muscles Thigh Muscles Select and Adjust Muscle Contractile Patterns Motor System Outputs Dynamic Control of the COG www.natus.com
- 20. Balance disorder/Different perspective Audiologist/ENT: Generally look at peripheral vestibular system Neurologist: Look at mainly central integration and Motor part. Geriatricians & Orthopedic specialists: Look at motor part and coordination
- 22. Rationale of dizzy test battery approach The ear has 10 sensory structure controlling the balance; Three semicircular canals (SCC) in each ear. Two Otolith organs Saccule and Utricle in each ear.
- 23. Rationale of dizzy test battery approach Innervated by Vestibular Nerve which divides in Sup and Inf vestibular Nerves. Sup Vest N supplies: Sup and Lateral SCC and Utricle. Inf Vest N supplies: Post SCC and the Saccule.
- 24. Dizzy test battery: Includes Complete Audiological Assessment (PTA, ABR & Ecoch.G) And Complete vestibular assessment (ENG, VAT, Rotary chair test, VEMP, CDP & DVAT)
- 25. WHAT DO WE LOOK FOR Vestibular Tests
- 26. Anatomical sites and causes of dizziness LSSC ASSC Utricle PSSC Saccule Sup Vest Nerve Inf. Vest Nerve Vestibular Nuclei Oculomotor Nuclei Eye Muscle Cerebellum Cerebral Cortex Eyes(vision) Spinal Cord Body Muscles Peripheral Central MLF RF Brainstem Oculomotor Pathways Eye Movement Postural Movement Vestibulospinal Pathways Vestibular tests Evaluate VOR, VCR & VSR There is no direct access to vestibular end organs
- 27. Audiological Evaluation. Tests Looks for Complete Hearing assessment Type and shape of H Loss may indicate the presence of diseases involving both hearing and balance disorders. Like Meniere’s Disease. (Fluctuating SN H Loss, Tinnitus, Dizziness and Fullness of ear) ABR Rules out Acoustic Neuroma and other retrocochlear pathologies. Ecoch.G Diagnostic test for Meniere’s Disease and Endolymphatic hydrops
- 28. Vestibular Function Tests. Test Looks for ENG Oculomotor Tests Dix Halpike Caloric Tests the Lateral SCC and also checks for central lesions involving vestibular system. Tests the Superior Vestibular Nerve. Also tests the BPPV. VAT (Vestibular Autorotation Test) Tests all the SCC canal including Lateral Sup and Inf SCC. Also tests the high frequency movements which cannot be tested with ENG. It compliments the results of ENG.
- 29. Vestibular Function Tests. Test Looks for Rotary Chair Test Tests the Lateral SCC . Test of choice for Bilateral canal paresis Inconclusive/equivocal ENG results Testing of special populations (pediatric, handicapped) Evaluation of vestibular compensation Ototoxicity management Tests the Superior Vestibular Nerve. vHIT (Video Head Impulse Test) Tests all the SCC canal including Lateral Sup and Inf SCC. Also tests the high frequency movements which cannot be tested with ENG. It compliments the results of ENG.
- 30. Vestibular Function Tests. Test Test cVEMP (Cervical Vestibular Evoked Myogenic Potentials) Checks for Saccule and Inf. vestibular nerve. (tinnitus and also compliments ABR for retrocochlear pathology) The only test which can check the Inf. Vestibular N Function. oVEMP (Ocular Vestibular Evoked Myogenic Potentials) Checks for Utricle and Sup Vest Nerve. (also compliments ABR for retrocochlear pathology)
- 31. Vestibular Disorder . Total number Abnormal number Normal number Meniere’s disease (Endolymphatic hydrops) 320 158 162 Vestibular schwannoma 306 238 68 SSCD 64 64 0 Tullio phenomenon 13 12 1 Vestibular neuritis/ Labyrinthitis 99 49 50 Sensorineural HL 46 4 42 Multiple sclerosis 167 101 66 VEMP: literature Review (1994-2006)*
- 32. Vestibular Functional Assessment Test Test BPPV Treatment Eply‘s, Semont’s and Log roll maneuver CDP (Computerized dynamic Posturography) It provides functional rather than site of lesion information. DVAT (Dynamic Visual Acuity Test) Test for oscillopsia associated with vestibular disorders.
- 33. Why Dizzy Battery As we can See no single test looks at all the vestibular sensory organs completely so the Test battery approach is recommended to completely evaluate the Balance function in a dizzy patient. This battery of tests performed together completely evaluates hearing and balance part of the ear (VIII N) including Superior and Inferior Vestibular Nerve.
- 34. VIII N Cochlear N Vestibular N PT A AB R Ecoch. G Sup. Vest. N Inf. Vest. N Ant.SCC Baseline thresholds Shape of audiogram Retrocochlear pathology/ VEMP may add credibility MD/EH Drop attacks Lat.SCC Utricle Post.SCC Saccule VAT/Positioni ng/vHIT Caloric/ Posiit.Rot Chair/vHIT VAT/Positioni ng/vHIT cVEMP PTA ABR Ecoch. G VEMP VAT/v HIT ENG oVEMP VAT ENG VEM P Dizzy battery PTA ABR Ecoch.G ENG Rotary Chair VAT oVEMP cVEMP vHIT Flow chart oVEMP
Editor's Notes
- Point to remember: Note the Vestibular nerve innervations of Sup and Inf. Vest N.
- Ant Vest Art follows the Sup Vest N Post Vest Art follows the In Vest N
- It is important to note the nerve distribution and the blood supply of vestibular system. Both can affect the balance. Like nerve can be affected in case of viral neuronitis or labyrinthits and blood supply can be affected by any vascular disease or cva affecting basilar artery or anterior inferior cerebellar artery
- Through Medial Longitudinal fasciculus to Occular Nerve (VOR) Through Vestibulospinal tract (Vestibulospinal reflex VSR) Through Vestibulocervical tract (Vestibulocoloic Reflex VCR)
- This is like presbyacoiuses, It has its implications on rehab. As you can see that there is no tonotopic innervation, so VRT will depend upon functional assessment determined by CDP.
- Let’s use our teaching Dynamic Equilibrium model to put this all together – examining the different systems, their interaction physiologically, as well as with the task and environment. Left side is the sensory input side - right side is motor output. The drivers of the balance systems: A Choice of Body Movement (volitional) or a reaction to a change in the environment (response) Peripheral Central – sensory integration area #39 [Cortical] – projections to……. This is a great model. It describes for us what we are trying to evaluate and treat relative to balance control. It also provides a basis for discussion about balance control – and as such is a great marketing (education) tool. Let’s think about the paradigms of the persons we speak with (market to) about our programs. [ASK THE AUDIENCE, SPECIFIC MEMBERS WHERE POSSIBLE] When I say balance to an ENT, where might they be focusing on this chart? An Audiologist? A Neurologist? An orthopedic therapist? [any other group you can think of based upon the audience’s composition]
- There are four types of motor responses that are of interest to us for balance control… Discuss each briefly.
- If we just do ENG we are just testing the Lateral SCC only and it will only give information about just 2 sensory organs out of 10 and Sup Vest N only. So having a normal ENG is not conclusive of the fact that vestibular system is normal. We can have normal Sup vestibular N function but may have vestibulopathy involving Inf Vestibular N. Therefore a test battery approach is recommended as it will test all the sensory structures and both Sup and Inf vestibular nerves.