Vestibular Function and Dysfunction Melanie Giesler.

Vestibular Function and Vestibular Function and DysfunctionDysfunction

Melanie GieslerMelanie Giesler

Vestibular Dysfunction Vestibular Dysfunction PrevalencePrevalence

Four percent of patients18-65 yo visit Four percent of patients18-65 yo visit PCP with complaint of “dizziness”PCP with complaint of “dizziness”

Three percent consider it “Severely Three percent consider it “Severely incapacitating”incapacitating”

Third most common complaint in Third most common complaint in elderlyelderly

Vestibular SystemVestibular System

System of balanceSystem of balance Membranous and bony labyrinth Membranous and bony labyrinth

embedded in petrous boneembedded in petrous bone 5 distinct end organs5 distinct end organs

3 semicircular canals: superior, lateral, 3 semicircular canals: superior, lateral, posteriorposterior

2 otolith organs: utricle and saccule2 otolith organs: utricle and saccule


Semicircular canals sense angular Semicircular canals sense angular accelerationacceleration

Otolithic organs (utricle and saccule) Otolithic organs (utricle and saccule) sense linear accelerationsense linear acceleration


Semicircular canals Semicircular canals are orthogonal to are orthogonal to each othereach other

Lateral canal Lateral canal inclined to 30 inclined to 30 degreesdegrees

Superior/postereor Superior/postereor canals 45 degrees canals 45 degrees off of sagittal planeoff of sagittal plane

Vestibular AnatomyVestibular Anatomy

Vestibular Blood SupplyVestibular Blood Supply

45% from AICA45% from AICA 24% superior 24% superior

cerebellar arterycerebellar artery 16% basilar16% basilar Two divisions: Two divisions:

anterior vestibular anterior vestibular and common and common cochlear arterycochlear artery

Vestibular Nerve SupplyVestibular Nerve Supply

Superior vestibular Superior vestibular nerve: superior nerve: superior canal, lateral canal, canal, lateral canal, utricleutricle

Inferior vestibular Inferior vestibular nerve: posterior nerve: posterior canal and sacculecanal and saccule

Vestibular FluidVestibular Fluid

Membranous labyrinth is surrounded Membranous labyrinth is surrounded by perilymphby perilymph

Endolymph fills the vestibular end Endolymph fills the vestibular end organs along with the cochleaorgans along with the cochlea


PerilymphPerilymph Similar to extracellular fluidSimilar to extracellular fluid K+=10mEQ, Na+=140mEq/LK+=10mEQ, Na+=140mEq/L Unclear whether this is ultrafiltrate of Unclear whether this is ultrafiltrate of

CSF or bloodCSF or blood Drains via venules and middle ear Drains via venules and middle ear

mucosamucosa


EndolymphEndolymph Similar to intracellular fluidSimilar to intracellular fluid K+=144mEq/L, Na+=5mEq/LK+=144mEq/L, Na+=5mEq/L Produced by marginal cells in stria Produced by marginal cells in stria

vascularis from perilymph at the cochlea vascularis from perilymph at the cochlea and from dark cells in the cristae and and from dark cells in the cristae and maculaemaculae

Absorbed in endolymphatic sac which Absorbed in endolymphatic sac which connected by endolymphatic, utricular connected by endolymphatic, utricular and saccular ductsand saccular ducts

Sensory StructuresSensory Structures

Ampulla of the semicircular canalsAmpulla of the semicircular canals Dilated end of canalDilated end of canal Contains sensory neuroepithelium, Contains sensory neuroepithelium,

cupula, supporting cellscupula, supporting cells

In the Ampulla…In the Ampulla…

Cupula is gelatinous Cupula is gelatinous mass extending mass extending across at right angleacross at right angle

Extends completely Extends completely across, not across, not responsive to responsive to gravitygravity

Crista ampullaris is Crista ampullaris is made up of sensory made up of sensory hair cells and hair cells and supporting cellssupporting cells


Hair cells have 50-100 stereocilia and a single kinocilium.


stereocilia are not true cilia, they are graded in height with tallest nearest the kinocilium.


Each afferent neuron has a baseline Each afferent neuron has a baseline firing ratefiring rate

Deflection of stereocilia toward Deflection of stereocilia toward kinocilium results in an increase in kinocilium results in an increase in the firing rate of the afferent neuronthe firing rate of the afferent neuron

Deflection away causes a decrease in Deflection away causes a decrease in the firing ratethe firing rate

Angular acceleration acts on Angular acceleration acts on the hair cells in the Ampullathe hair cells in the Ampulla

Angular acceleration acts on Angular acceleration acts on the hair cells in the Ampullathe hair cells in the Ampulla

Kinocilia are located closest to utricle Kinocilia are located closest to utricle in lateral canals and are on in lateral canals and are on canalicular side in other canalscanalicular side in other canals

Ampullopetal flow (toward the Ampullopetal flow (toward the ampulla) excitatory in lateral canals, ampulla) excitatory in lateral canals, inhibitory in superior/posterior canals inhibitory in superior/posterior canals

Ampullofugal flow (away from the Ampullofugal flow (away from the ampulla) has opposite effectampulla) has opposite effect

Physiology Semicircular Physiology Semicircular CanalsCanals

Semicircular canals Semicircular canals are pairedare paired Horizontal canalsHorizontal canals Right superior/left Right superior/left

posteriorposterior Left superior/right Left superior/right

posteriorposterior Allow redundant Allow redundant

reception of movementreception of movement Explains compensation Explains compensation

after unilateral after unilateral vestibular lossvestibular loss

Otolithic OrgansOtolithic Organs

Utricle and saccule sense linear Utricle and saccule sense linear accelerationacceleration

Cilia from hair cells are embedded in Cilia from hair cells are embedded in gelatinous layer gelatinous layer

Otoliths or otoconia are on upper Otoliths or otoconia are on upper surfacesurface

Otolithic OrgansOtolithic Organs

Calcium carbonate Calcium carbonate or calciteor calcite

0.5-30um0.5-30um Specific gravity of Specific gravity of

otolithic membrane otolithic membrane is 2.71-2.94is 2.71-2.94

Central region of Central region of otolithic membrane otolithic membrane is called the striolais called the striola

Vestibular PhysiologyVestibular Physiology

Senses and controls Senses and controls motionmotion

Information is Information is combined with that combined with that from visual system from visual system and proprioceptive and proprioceptive systemsystem

Maintains balance and Maintains balance and compensates for compensates for effects of head motioneffects of head motion

Vestibulo-ocular reflexVestibulo-ocular reflex

Vestibulo-ocular reflexVestibulo-ocular reflex Membranous labyrinth Membranous labyrinth

moves with head motionmoves with head motion Endolymph does not Endolymph does not

causing relative motioncausing relative motion Cupula on right canal Cupula on right canal

deflected towards utricle deflected towards utricle causing increase in causing increase in firing rate, left deflects firing rate, left deflects away causing a away causing a decrease in firing rate.decrease in firing rate.

Reflex causes Reflex causes movement of eyes to movement of eyes to the left with saccades to the left with saccades to rightright

Stabilizes visual imageStabilizes visual image

NystagmusNystagmus

If acceleration stops, and spin to right is at If acceleration stops, and spin to right is at constant velocity, sensation of motion constant velocity, sensation of motion stops after 14-20 seconds as does stops after 14-20 seconds as does nystagmusnystagmus

Cupula only takes 8-10 seconds to return Cupula only takes 8-10 seconds to return to equilibrium positionto equilibrium position

Vestibular integrator is the term for the Vestibular integrator is the term for the prolongation and is mediated by the prolongation and is mediated by the vestibular nuclei and cerebellumvestibular nuclei and cerebellum

Vestibulospinal ReflexVestibulospinal Reflex

Senses head movement and head Senses head movement and head relative to gravityrelative to gravity

Projects to antigravity muscles via 3 Projects to antigravity muscles via 3 major pathways:major pathways: Lateral vestibulospinal tractLateral vestibulospinal tract Medial vestibulospinal tractMedial vestibulospinal tract Reticulospinal tractReticulospinal tract

Office Examination of the Dizzy Office Examination of the Dizzy PatientPatient

Dix-Hallpike ManeuverDix-Hallpike Maneuver Used to provoke nystagmus and vertigo Used to provoke nystagmus and vertigo

commonly associated with BPPVcommonly associated with BPPV Head turned 45 degrees to maximally Head turned 45 degrees to maximally

stimulate posterior semicircular canalstimulate posterior semicircular canal Head supported and rapidly placed into Head supported and rapidly placed into

head hanging positionhead hanging position Frenzel glasses eliminate visual fixation Frenzel glasses eliminate visual fixation

suppression of responsesuppression of response

Dix-Hallpike ManuveurDix-Hallpike Manuveur

Dix-Hallpike ManuveurDix-Hallpike Manuveur

Positive testPositive test Up-beating nystagmusUp-beating nystagmus Nystagmus to the stimulated sideNystagmus to the stimulated side Rotary component to the affected earRotary component to the affected ear Lasts 15-45 secondsLasts 15-45 seconds Latency of 2-15 secondsLatency of 2-15 seconds Fatigues easilyFatigues easily

Pneumatic OtoscopyPneumatic Otoscopy

Positive and negative pressure applied Positive and negative pressure applied to middle earto middle ear

Hennebert’s sign/symptom – nystagmus Hennebert’s sign/symptom – nystagmus and vertigo with pressure, alternates and vertigo with pressure, alternates with positive and negative pressurewith positive and negative pressure

Can be present in patients with Can be present in patients with perilymphatic fistula, syphilis, perilymphatic fistula, syphilis, Meninere’s disease, SCC dehiscence Meninere’s disease, SCC dehiscence syndromesyndrome

Head Shake NystagmusHead Shake Nystagmus

Evaluates unilateral vestibular weaknessEvaluates unilateral vestibular weakness Head tilted back 30 degreesHead tilted back 30 degrees Shake back and forth for 30 seconds as Shake back and forth for 30 seconds as

quickly as possiblequickly as possible Unilateral vestibular deficit causes slow Unilateral vestibular deficit causes slow

phase nystagmus to the side of lesionphase nystagmus to the side of lesion Low sensitivity (27%) Low sensitivity (27%) Good specificity (85%)Good specificity (85%)

Head Thrust TestHead Thrust Test

Inhibitory response not as robust as the Inhibitory response not as robust as the stimulatory response to stimulate VORstimulatory response to stimulate VOR

Movements that overcome the inhibitory Movements that overcome the inhibitory response of vestibule will result in VOR lagresponse of vestibule will result in VOR lag

Head tilted 30 degrees Head tilted 30 degrees Rapid head movements to either side with Rapid head movements to either side with

focus on examiner’s nosefocus on examiner’s nose Patients have catch-up saccade when Patients have catch-up saccade when

rotated to side of weaknessrotated to side of weakness Sensitivity 75%, Specificity of 85% Sensitivity 75%, Specificity of 85%

Dynamic Visual AcuityDynamic Visual Acuity

Used for bilateral vestibular weaknessUsed for bilateral vestibular weakness Visual acuity checked on Snellen chartVisual acuity checked on Snellen chart Rechecked while rotating head back and Rechecked while rotating head back and

forth at 1-2 Hz.forth at 1-2 Hz. Loss of 2-3 lines considered abnormal – Loss of 2-3 lines considered abnormal –

usually b/l loss due to ototoxicity or usually b/l loss due to ototoxicity or aging.aging.

Romberg TestRomberg Test

Patient asked to stand with feet Patient asked to stand with feet together and eyes closedtogether and eyes closed

Fall or step is positive testFall or step is positive test Equal sway with eyes open and closed Equal sway with eyes open and closed

suggests proprioceptive or cerebellar suggests proprioceptive or cerebellar sitesite

More sway with eyes closed suggests More sway with eyes closed suggests vestibular weaknessvestibular weakness

Fukuda Stepping TestFukuda Stepping Test

Originally described by Fukuda using 100 steps Originally described by Fukuda using 100 steps on a marked floor.on a marked floor.

Patients are asked to step with eyes closed and Patients are asked to step with eyes closed and hands out in fronthands out in front

Rotation by more than 45 degrees is abnormalRotation by more than 45 degrees is abnormal Rotation usually occurs to the side of the lesionRotation usually occurs to the side of the lesion Rotation often found in asymptomatic patientsRotation often found in asymptomatic patients

Dysdiadochokinesia TestingDysdiadochokinesia Testing

Most commonly tested with the hand Most commonly tested with the hand slapping testslapping test

Abnormalities seen in patients with Abnormalities seen in patients with cerebellar dysfunctioncerebellar dysfunction

Poor sensitivity and specificityPoor sensitivity and specificity

Tandem Gait TestTandem Gait Test

Patients are asked to walk heal to toe Patients are asked to walk heal to toe in a straight line or in a circlein a straight line or in a circle

Complex function evaluates many Complex function evaluates many aspects of balanceaspects of balance

Poor performance seen in cerebellar Poor performance seen in cerebellar lesions, but can be seen in many lesions, but can be seen in many disordersdisorders

Poor sensitivity and specificityPoor sensitivity and specificity

Orthostatic HypotensionOrthostatic Hypotension

Most often in patients on BP meds with Most often in patients on BP meds with “light headedness” on sitting to standing“light headedness” on sitting to standing

Defined as drop of SBP 20mm HG or DPB Defined as drop of SBP 20mm HG or DPB 10mm HG within 3 minutes of standing10mm HG within 3 minutes of standing

Tilt exams offer objective measurements Tilt exams offer objective measurements with well established normswith well established norms

Patients with no symptoms will often “Tilt”Patients with no symptoms will often “Tilt”

Voluntary HyperventilationVoluntary Hyperventilation

Patients asked to over breathe for 90 Patients asked to over breathe for 90 seconds to 3 minutes (elevate pH – seconds to 3 minutes (elevate pH – vasoconstriction)vasoconstriction)

Hyperventilation causes symptoms in Hyperventilation causes symptoms in some anxiety disorderssome anxiety disorders

May provoke symptoms in normalMay provoke symptoms in normal Poor test for vestibular diagnosis but can Poor test for vestibular diagnosis but can

elevate pH, increase 8elevate pH, increase 8thth nerve firing - nerve firing - lesions in petrous apex, acoustic lesions in petrous apex, acoustic schwannoma, 8schwannoma, 8thth nerve demylination nerve demylination

Electronystagmography Electronystagmography (ENG)(ENG)

Divided into oculomotor tests, positional Divided into oculomotor tests, positional and positioning tests, and caloric testsand positioning tests, and caloric tests

Only vestibular test with the ability to Only vestibular test with the ability to test individual labyrinths separatelytest individual labyrinths separately

Relies on the vestibulo-ocular reflex Relies on the vestibulo-ocular reflex (VOR) to test the peripheral vestibular (VOR) to test the peripheral vestibular functionfunction

Mostly a test of HSCC function Mostly a test of HSCC function

Electronystagmography Electronystagmography (ENG)(ENG)

Oculomotor testsOculomotor tests All test eye movements that originate in All test eye movements that originate in

the cerebellumthe cerebellum Saccadic trackingSaccadic tracking Smooth pursuit trackingSmooth pursuit tracking Optokinetic testingOptokinetic testing

Oculomotor TestsOculomotor Tests

Saccadic trackingSaccadic tracking Patients concentrates on a randomly Patients concentrates on a randomly

moving targetmoving target Latency – difference in time between Latency – difference in time between

movement of object and eye (150-250 ms)movement of object and eye (150-250 ms) Velocity – speed of saccade 200-400 Velocity – speed of saccade 200-400

degrees/second low end of normaldegrees/second low end of normal Accuracy – amount of undershoot/overshoot Accuracy – amount of undershoot/overshoot

of target (75-120%) of target (75-120%)

Smooth Pursuit TestSmooth Pursuit Test

Tests ability to accurately and Tests ability to accurately and smoothly pursue a targetsmoothly pursue a target

Gain of eyes compared to movement Gain of eyes compared to movement of targetof target

Saccade movements eliminated from Saccade movements eliminated from calculationscalculations

Asymmetrical pursuit highly Asymmetrical pursuit highly suggestive of central disorderssuggestive of central disorders

Optokinetic TestsOptokinetic Tests

Vestibular system and optokinetic Vestibular system and optokinetic nystagmus allow steady focus on nystagmus allow steady focus on objectsobjects

Target is rapidly passed in front of Target is rapidly passed in front of subject in one direction, then the othersubject in one direction, then the other

Eye movements are recorded and Eye movements are recorded and compared in each directioncompared in each direction

Asymmetry suggestive of CNS lesionAsymmetry suggestive of CNS lesion High rate of false positive resultsHigh rate of false positive results

Caloric TestingCaloric Testing

Established and widely accepted method Established and widely accepted method of vestibular testingof vestibular testing

Most sensitive test of unilateral Most sensitive test of unilateral vestibular weaknessvestibular weakness

Patient positioned 30 degrees from Patient positioned 30 degrees from prone (HSCC vertical allowing max stim)prone (HSCC vertical allowing max stim)

Cold and warm water/air flushed into Cold and warm water/air flushed into EACEAC

How Do Calorics Work?How Do Calorics Work?

Patient is lying down Patient is lying down with horizontal canals with horizontal canals oriented vertically oriented vertically (ampulla up)(ampulla up)

Cold water irrigation Cold water irrigation causes endolymph in causes endolymph in lateral portion to lateral portion to become dense and fall become dense and fall causing deflection of causing deflection of cupula away from utricle cupula away from utricle with a decrease in the with a decrease in the firing ratefiring rate

This causes nystagmus This causes nystagmus with fast phase (beat) with fast phase (beat) away from the stimulusaway from the stimulus

How Do Calorics Work?How Do Calorics Work?

With warm water With warm water irrigation column of irrigation column of endolymph becomes endolymph becomes less dense, rises and less dense, rises and causes deflection of causes deflection of cupula toward the cupula toward the utricleutricle

Results in increase Results in increase firing rate and firing rate and nystagmus which beats nystagmus which beats towards the towards the stimulationstimulation

COWS (cold opposite, COWS (cold opposite, warm same)warm same)

Rotational Chair TestingRotational Chair Testing

Gold standard” in identifying bilateral Gold standard” in identifying bilateral vestibular lesionsvestibular lesions

Used to monitor for progressive bilateral Used to monitor for progressive bilateral vestibular loss (gentamicin toxicity)vestibular loss (gentamicin toxicity)

Used to quantify bilateral vestibular loss – Used to quantify bilateral vestibular loss – vestibular rehab vs. balance trainingvestibular rehab vs. balance training

Useful in testing children that will not Useful in testing children that will not allow caloric irrigationsallow caloric irrigations

Used with borderline caloric tests when Used with borderline caloric tests when water calorics cannot be used water calorics cannot be used

Rotational Chair TestingRotational Chair Testing

PosturographyPosturography

Used to tests integration of balance Used to tests integration of balance systemssystems

Useful in quantification of fall riskUseful in quantification of fall risk Most useful in following conditions:Most useful in following conditions:

Chronic disequilibrium and normal examsChronic disequilibrium and normal exams Suspected malingeringSuspected malingering Suspected multifactorial disequilibriumSuspected multifactorial disequilibrium Poorly compensated vestibular injuriesPoorly compensated vestibular injuries


5/6 – Vestibular dysfunction5/6 – Vestibular dysfunction2,3,5,6 – somatosensory and 2,3,5,6 – somatosensory and vestibular dysfunctionvestibular dysfunction3,6 – visual preference3,6 – visual preference1,2,3,4 or any combination with 1,2,3,4 or any combination with normal 5/6 - aphysiologicnormal 5/6 - aphysiologic

Dizzy Patient EvaluationDizzy Patient Evaluation

History – will give diagnosis in majority of disordersHistory – will give diagnosis in majority of disorders PhysicalPhysical

Head and Neck Exam Head and Neck Exam Spontaneous nystagmus on trackingSpontaneous nystagmus on tracking

Vertical or direction changing nystagmus = Vertical or direction changing nystagmus = MRI and neurology referral MRI and neurology referral

Pneumatic OtoscopyPneumatic Otoscopy If positive If positive consider consider diagnosis of fistula, Meninere’s, syphilisdiagnosis of fistula, Meninere’s, syphilis

Dix HallpikeDix Hallpike If positive, Eply maneuver twice, if still dizzy, ENGIf positive, Eply maneuver twice, if still dizzy, ENG

Head thrust test alone or with head shake nystagmus Head thrust test alone or with head shake nystagmus If positive, start vestibular exercisesIf positive, start vestibular exercises If no response - ENGIf no response - ENG

Rhomberg Test Rhomberg Test If equal sway with eyes closed and open neurology referral, ENGIf equal sway with eyes closed and open neurology referral, ENG


Fukuda stepping test if suspected vestibular Fukuda stepping test if suspected vestibular dysfunction and normal head shake/head thrust dysfunction and normal head shake/head thrust tests, or proceed to ENGtests, or proceed to ENG

Orthostatic measurements if directed by historyOrthostatic measurements if directed by history Dynamic visual acuity if possibility of bilateral Dynamic visual acuity if possibility of bilateral

lossloss AudiogramAudiogram

Obtain in every dizzy patient. Cost effective Obtain in every dizzy patient. Cost effective exam for acoustic neuroma, useful in other exam for acoustic neuroma, useful in other diagnosisdiagnosis


ENG Patients unresponsive to conservative treatment Severe symptoms are not suspicious of acute

vestibular infection Diagnosis uncertain and chronic symptoms Pre-op when vestibular ablation procedure

considered When documentation of vestibular function is

necessary When referred from neurology for evaluation


MRIMRI Any suspicion of central lesions by Any suspicion of central lesions by

physical, or objective testingphysical, or objective testing

Posturography/Chair testing/VEMPPosturography/Chair testing/VEMP

Not widely availableNot widely available

Of questionable clinical utilityOf questionable clinical utility

TreatmentTreatment

No ideal drugNo ideal drug Symptomatic txSymptomatic tx

control acute sx control acute sx Specific txSpecific tx

target underlying target underlying causecause

AnticholinergicsAnticholinergics AntihistaminesAntihistamines AntidopaminergicsAntidopaminergics MonaminergicsMonaminergics GABAergicsGABAergics

Specific TreatmentSpecific Treatment

Otosyphilis – PCNOtosyphilis – PCN Vertebrobasilar Insufficiency - TiclidVertebrobasilar Insufficiency - Ticlid Migraine – B-blocker (peds); Ca ch Migraine – B-blocker (peds); Ca ch

blocker/TCAs (adults)blocker/TCAs (adults) Vestibular Neuritis – antivirals/steroidsVestibular Neuritis – antivirals/steroids Meniere’s Disease – thiazides/Na restriction, Meniere’s Disease – thiazides/Na restriction,

vasodilators, chemical labrinthectomy with vasodilators, chemical labrinthectomy with streptomycin (IM) or gentamycin streptomycin (IM) or gentamycin (intratympanic)(intratympanic)

BPPV - EpleyBPPV - Epley

Vestibular Function and Dysfunction Melanie Giesler.

Documents

Transcript of Vestibular Function and Dysfunction Melanie Giesler.