investigating a dizzy patient

MOHAMMAD, S ASGHARTHE EAR INSTITUTE AUDIOLOGY CLINIC,

SCARBOROUGH GENERAL HOSPITAL,SCARBOROUGH, ON

Investigating a Dizzy patientDizzy Battery at a Glance

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.

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.

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.

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.

Anatomic and Basic Medical considerations

Anatomy of the vestibular system

Inner Ear:Bony and Membranous Labyrinths

Medial View

Anatomy of Vestibular System

Blood supply of Inner Ear

Irrigation ParallelsInnervation

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 

Vertebro-basilar arteries

Vertebro-basilar arteries

Vestibular system: central connections

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

Anatomic and Basic Medical considerations:

Multiple sensory inputs contribute to balance function.

Vestibular end organVisual 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.

Balance system

VisualSystem

Sensory Motor

EnvironmentalInteraction

Compare, Selectand Combine Senses

Select and AdjustMuscle Contractile Patterns

Generation ofBody Movement

VestibularSystem

Somato-Sensation

AnkleMuscles

TrunkMuscles

ThighMuscles

Initiate Automatic/Voluntary Movements

Determine BodyPosition

www.natus.com

Dynamic Equilibrium(The concept)

Central integratio

n

• Reflexes• Automatic and

adaptive postural responses

• Anticipatory postural set

• Voluntary movements

AnkleMuscle

s

Generation ofBody Movement

TrunkMuscle

s

ThighMuscle

s

Select and AdjustMuscle Contractile Patterns

Motor System Outputs Dynamic Control of the COG

www.natus.com

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

DIZZY TEST BATTERY

Rational for

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.

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.

Dizzy test battery:

Includes

Complete Audiological Assessment (PTA, ABR & Ecoch.G)

And Complete vestibular assessment (ENG, VAT, Rotary chair test, VEMP, CDP &

DVAT)

WHAT DO WE LOOK FOR

Vestibular Tests

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 CordBody

MusclesPeripheral

Central

MLF

RF

Brainstem Oculomotor Pathways

Eye Movement

Postural Movement

Vestibulospinal Pathways

Vestibular tests Evaluate VOR, VCR & VSRThere is no direct access to vestibular end organs

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

Vestibular Function Tests.

Test Looks for

ENGOculomotor TestsDix 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.

Vestibular Function Tests.

Test Looks for

Rotary Chair Test

Tests the Lateral SCC . Test of choice for Bilateral canal paresisInconclusive/equivocal ENG resultsTesting of special populations (pediatric, handicapped)Evaluation of vestibular compensationOtotoxicity 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.

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)

Vestibular Disorder . Total number Abnormalnumber

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)*

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.

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.

VIII N

Cochlear N

Vestibular N

PTA

ABR

Ecoch.G

Sup. Vest. N

Inf. Vest. N

Ant.SCC

Baseline thresholdsShape of audiogramRetrocochlear pathology/VEMP may add credibility

MD/EHDrop attacks

Lat.SCC

Utricle

Post.SCC

Saccule

VAT/Positioning/

vHITCaloric/

Posiit.Rot Chair/vHIT

VAT/Positioning/

vHITcVEM

P

PTAABR

Ecoch.G

VEMP

VAT/vHITENG

oVEMP

VATENGVEM

P

Dizzy batter

yPTAABR

Ecoch.G

ENGRotaryChairVAT

oVEMPcVEMPvHIT

Flow chart

oVEMP