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
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