The incidence of 30/01/11 evening when TWO ON The incidence of 30/01/11 evening when TWO ON DUTY DOCTORS were shot by a legislatorDUTY DOCTORS were shot by a legislator

We condemn the inhuman and antisocial act

DO YOU?

ASSESSMENT OF ASSESSMENT OF HEARINGHEARING

by:- Dr ZEESHAN AHMADNMCH PATNA INDIA

DECIBEL(dB)=1/10 Bel

• Bel is a base10 logarithmic ratio of intensity of given sound to threshold of hearing in normal subjects at 1000Hz

• The decibel originates from methods used to quantify reductions in audio levels in telephone circuits

• 1MSC=loss in 1 mile = 1.6Km• 1.056 TU = 1 MSC)• 1TU=1/10 Bel=1dB• Named after Alexander Graham Bell who

invented the telephone

Pathways for air and bone conduction

Auditory cortex

MGB

Inferior collliculus

Lateral lemniscus

Olivary nucleus(superior)

Cochlear nucleus

Eight cranial nerve

E.COLI-MA

PL Dhingra has simplified auditory pathway and made it easier to remember by a mnemonic

Tuning Fork TestsTuning Fork Tests

Tuning Fork Tests Tuning Fork Tests

Tuning fork is a device usually made of steel, magnesium or aluminum Tuning fork is a device usually made of steel, magnesium or aluminum that is used to tune musical instruments by musicians and we the doctors that is used to tune musical instruments by musicians and we the doctors use it to assess hearinguse it to assess hearing

We can set it into vibration by holding We can set it into vibration by holding the stem/handle in the hand and striking one the stem/handle in the hand and striking one of the tines against a firm but resilient surfaceof the tines against a firm but resilient surface It emits a tone at a particular pitch and has a clear musical qualityIt emits a tone at a particular pitch and has a clear musical quality It vibrates sinusoidally to generate a pure toneIt vibrates sinusoidally to generate a pure tone

When it vibrates properly, the tines move alternately away from and When it vibrates properly, the tines move alternately away from and toward one another toward one another

Several forks are available, each correspond to notes on the musical scale. Several forks are available, each correspond to notes on the musical scale. We have the following frequencies (4096, 2048,1024, 512, 256, 128, 64) We have the following frequencies (4096, 2048,1024, 512, 256, 128, 64) HzHz

Tuning Fork TestsTuning Fork Tests

Used before the development of audiometers with BC and Used before the development of audiometers with BC and the other sophisticated electronic devicesthe other sophisticated electronic devices

A century ago, they were used widely as an instrument A century ago, they were used widely as an instrument for testing hearingfor testing hearing

They illustrate the principles involved in certain modern They illustrate the principles involved in certain modern tests tests

Their use has declined but are still used by many Their use has declined but are still used by many physicians in their everyday practicephysicians in their everyday practice

Principle of Tuning Fork TestsPrinciple of Tuning Fork Tests

CHLCHL (OE or ME Disorder) (OE or ME Disorder)

Sounds delivered to the ear via AC will be attenuated Sounds delivered to the ear via AC will be attenuated If the sound is delivered to the ear via BC, bypassing the OE If the sound is delivered to the ear via BC, bypassing the OE

& ME, then the sound will be heard normally assuming & ME, then the sound will be heard normally assuming there is no disorder there is no disorder

SNHLSNHL (OE & ME Are Free From Disorders) (OE & ME Are Free From Disorders)

Sounds delivered to the ear via BC will be attenuated Sounds delivered to the ear via BC will be attenuated

Standard Tuning Fork TestsStandard Tuning Fork Tests

Purpose: Purpose: to diagnose the type of HLto diagnose the type of HL

Results from these tests are determined by the presence or Results from these tests are determined by the presence or absence of an occlusion effectabsence of an occlusion effect

1)1) Schwabach TestSchwabach Test2)2) Bing Bing 3)3) RinneRinne4)4) WeberWeber

Various positions of tuning fork during tuning fork tests

On mastoid

At the opening of EAC

Midline of skull

Schwabach TestSchwabach Test

Was once popular but no longer is in general use Was once popular but no longer is in general use

It compares pt’s hearing sensitivity with that of an examiner (assuming It compares pt’s hearing sensitivity with that of an examiner (assuming that he/she has a normal hearing)that he/she has a normal hearing)

The fork is set into vibration, stem is placed alternately against the The fork is set into vibration, stem is placed alternately against the mastoid process of the pt. and of the examinermastoid process of the pt. and of the examiner

Pt. should indicate whether the tone is heard or not each time the fork is Pt. should indicate whether the tone is heard or not each time the fork is placed is pressed against his/her mastoid processplaced is pressed against his/her mastoid process

Vibratory energy of the tines of fork decreases overtime, making the tone Vibratory energy of the tines of fork decreases overtime, making the tone softersofter

When the pt. no longer hears the tone, examiner immediately places the When the pt. no longer hears the tone, examiner immediately places the stem behind his or her own ear and using a watch, notes the number of stem behind his or her own ear and using a watch, notes the number of seconds the tone is audible after the pt. stops hearing itseconds the tone is audible after the pt. stops hearing it

Schwabach TestSchwabach Test

Normal Schwabach:Normal Schwabach: Both pt. & examiner stop hearing the tone at approximately the same Both pt. & examiner stop hearing the tone at approximately the same

time time Pt. has normal BCPt. has normal BC Pt. has normal hearing or CHLPt. has normal hearing or CHL Diminished Schwabach:Diminished Schwabach: Pt. stop hearing the sound much sooner than the examinerPt. stop hearing the sound much sooner than the examiner Pt. BC is impairedPt. BC is impaired Pt. has SNHLPt. has SNHL

Schwabach TestSchwabach Test

Can be quantified by recording the number of seconds an examiner Can be quantified by recording the number of seconds an examiner continues to hear the tone after a pt. has stopped hearing it continues to hear the tone after a pt. has stopped hearing it

Examiner hears the tone 10 sec longer than a pt. Examiner hears the tone 10 sec longer than a pt. pt. hearing is pt. hearing is “Diminished 10 seconds”“Diminished 10 seconds”

If pt. has CHL, BC is normal and they are expected to hear the tone for at If pt. has CHL, BC is normal and they are expected to hear the tone for at least as long as the examinerleast as long as the examiner

In some CHL, the pt’s hearing in the low-pitch range may appear better In some CHL, the pt’s hearing in the low-pitch range may appear better than normal, called than normal, called “Prolonged Schwabach”“Prolonged Schwabach”

Disadvantages:Disadvantages: Difficulties in the administration and interpretation of test Difficulties in the administration and interpretation of test in cases of MHLin cases of MHL plus it requires normal hearing by the examinerplus it requires normal hearing by the examiner

Bing TestBing Test

Premise:Premise:

Persons with Normal hearing and SNHL when they close off the opening of Persons with Normal hearing and SNHL when they close off the opening of the ear canal, loudness of a tone presented by BC increases the ear canal, loudness of a tone presented by BC increases “ Occlusion “ Occlusion Effect”Effect”

Observed primarily for low-pitched soundsObserved primarily for low-pitched sounds

Absent in pts. with CHLAbsent in pts. with CHL

Bing TestBing Test

Assesses the presence of CHLAssesses the presence of CHL

Tuning fork is placed on the pt.'s mastoid, while the ear canal is Tuning fork is placed on the pt.'s mastoid, while the ear canal is alternatively opened and closed by the examiner by depressing tragusalternatively opened and closed by the examiner by depressing tragus and and the pt. is asked to state which position is louder the pt. is asked to state which position is louder

When the ear canal is closed on a person with normal hearing or SNHL, When the ear canal is closed on a person with normal hearing or SNHL, low-frequency bone conducted signals are heard more loudly (Occlusion low-frequency bone conducted signals are heard more loudly (Occlusion Effect), the is a Effect), the is a "Positive Bing“"Positive Bing“

Pts. with CHL will not experience this sensation and the tone will be the Pts. with CHL will not experience this sensation and the tone will be the same when the ear canal is open and closed and the test will be a same when the ear canal is open and closed and the test will be a "Negative Bing""Negative Bing" because the ear already has a conductive impairment because the ear already has a conductive impairment

Rinne TestRinne Test

Compares pts' hearing sensitivity by BC to their sensitivity by ACCompares pts' hearing sensitivity by BC to their sensitivity by AC The tuning fork is set into vibration and held close the pt's earThe tuning fork is set into vibration and held close the pt's ear Tuning fork is alternatively held to the ear and then the base is placed on Tuning fork is alternatively held to the ear and then the base is placed on

the mastoid processthe mastoid process pt. is asked to state where the tone is louder, at the ear or at the mastoidpt. is asked to state where the tone is louder, at the ear or at the mastoid

Pts. with Pts. with normal hearing and SNHLnormal hearing and SNHL will hear the tone louder at the ear will hear the tone louder at the ear (Because AC is a more efficient means of sound transmission to the IE (Because AC is a more efficient means of sound transmission to the IE than BC) than behind the ear than BC) than behind the ear (Positive Rinne)(Positive Rinne)

Pts. with Pts. with CHL (more than mild) or MHLCHL (more than mild) or MHL will hear the tone louder with the will hear the tone louder with the stem of the fork behind the ear because their BC hearing is better than stem of the fork behind the ear because their BC hearing is better than their AC hearing their AC hearing (Negative Rinne)(Negative Rinne)

DisadvantagesDisadvantages

In Schwaback test, Bing test and Rinne Test:In Schwaback test, Bing test and Rinne Test:

There is always a danger of getting a response to the tone by the non-test There is always a danger of getting a response to the tone by the non-test ear (especially if the BC of the non-test ear is more sensitive than the BC ear (especially if the BC of the non-test ear is more sensitive than the BC of the test ear of the test ear ((

False negative results may occur False negative results may occur

Give rise to improper diagnosis of CHLGive rise to improper diagnosis of CHL

Weber TestWeber Test

A test of lateralizationA test of lateralization

Used for pts. reporting unilateral HLUsed for pts. reporting unilateral HL

The examiner places the stem of the tuning fork on the midline against the pt's The examiner places the stem of the tuning fork on the midline against the pt's foreheadforehead

The pt. should state if the tone is heard in the left ear, right ear, both ears or in The pt. should state if the tone is heard in the left ear, right ear, both ears or in the midlinethe midline

Weber effect is based onWeber effect is based on “Stenger Principle”:“Stenger Principle”: If two tones are identical except they are different in loudness, are introduced If two tones are identical except they are different in loudness, are introduced

simultaneously into both ears, only the louder tone will be perceived simultaneously into both ears, only the louder tone will be perceived

Two ears, one has poorer BC sensitivity, when the tone is being produced to Two ears, one has poorer BC sensitivity, when the tone is being produced to both ears with equal energy, the tone will be perceived softer or will not be both ears with equal energy, the tone will be perceived softer or will not be perceived at all in the poor earperceived at all in the poor ear

If the tone lateralizes to the poorer ear:If the tone lateralizes to the poorer ear:

That ear has improved BC sensitivityThat ear has improved BC sensitivity CHL in the poor ear CHL in the poor ear

If the tone lateralizes to the better/good ear:If the tone lateralizes to the better/good ear:

The cochlea with the best hearing sensitivity will detect the signalThe cochlea with the best hearing sensitivity will detect the signal SNHL or MHL in the poor earSNHL or MHL in the poor ear

If the sound is detected in the midline position:If the sound is detected in the midline position:

Normal hearingNormal hearing or equal amounts of the same type of HL in both ears (CHL, SNHL or MHL) or equal amounts of the same type of HL in both ears (CHL, SNHL or MHL)

If the sound lateralizes to the ear with greater conductive component:If the sound lateralizes to the ear with greater conductive component: Pt. has a bilateral lossPt. has a bilateral loss

Weber TestWeber Test

Advantages: Advantages:

QuickQuick EasyEasy Often helpfulOften helpful

Disadvantages:Disadvantages:

Difficult to interpret results in cases of unilateral CHL and MHLDifficult to interpret results in cases of unilateral CHL and MHL

Pure Tone AudiometryPure Tone Audiometry

Pure Tone AudiometryPure Tone Audiometry

-Audiometer is an electronic device which produces PURE TONES ,the intensity of which can be increased or decreased by 5dB steps

-Air conduction thresholds are measured from 125 to 8000 Hz

-Bone conduction thresholds from 250 to 4000 Hz

-The intensity of sound to be raised above normal to make it hear is a measure of degree of hearing impairment

-This is charted on a graph called AUDIOGRAM

Those mysterious markingsThose mysterious markings

Legends for PTA’sLegends for PTA’s

Air conductionAir conduction

Bone conductionBone conduction

How they do it (briefly)How they do it (briefly)

1.1. Otoscopy + explanationOtoscopy + explanation

2.2. Best ear?Best ear?

3.3. Start with AC on best earStart with AC on best ear

4.4. Start at 1000Hz at 60dBStart at 1000Hz at 60dB

5.5. Down by 10dB until no responseDown by 10dB until no response

6.6. Then up by 5dB until reponse (3 out of 5)Then up by 5dB until reponse (3 out of 5)

7.7. Up and down frequenciesUp and down frequencies

8.8. Same for boneSame for bone

Important concept…Important concept…

At Iowa State Fair in 1935, 10 At Iowa State Fair in 1935, 10 000 young women had 000 young women had their hearing measuredtheir hearing measured

This established the normal This established the normal hearing levels for pure tone hearing levels for pure tone Audiometry (0 db Audiometry (0 db Threshold)Threshold)

It’s a Normal PTAIt’s a Normal PTASensorineuronal/conductive abnormality ??

Pure Tone AveragePure Tone Average

--Degree of hearing loss is --Degree of hearing loss is computed by using average of computed by using average of HTL taken at 500 Hz, 1,000 Hz HTL taken at 500 Hz, 1,000 Hz and 2,000 Hz.and 2,000 Hz.

--The average of these three --The average of these three frequencies is called the Pure frequencies is called the Pure Tone Average or PTA and is the Tone Average or PTA and is the degree of hearing loss a person degree of hearing loss a person has expressed in dBhas expressed in dB

Hearing Loss TableHearing Loss Table

PTAPTA ClassificationClassification

0-200-20 NormalNormal

21-4021-40 Mild hearing lossMild hearing loss

41-6041-60 Moderate HLModerate HL

61-7061-70 Moderately severe HLModerately severe HL

71-9071-90 Severe HLSevere HL

>90>90 Profound hearing lossProfound hearing loss

And, we all know BC is not as good And, we all know BC is not as good as AC, don’t we?as AC, don’t we?

So, why does a So, why does a normal PTA look normal PTA look like this?like this?

Conductive LossConductive LossWhat’s this shows

Sensorineural LossSensorineural Loss

Mixed LossMixed LossNow what does this one shows

MaskingMasking

Used to prevent non-Used to prevent non-test ear hearing test ear hearing stimulus presented stimulus presented to test earto test ear

Interaural attenuationInteraural attenuation

BoneBoneAssumed to be 0dB, but probably Assumed to be 0dB, but probably

nearer 4-6dBnearer 4-6dB AirAirAssumed to be greater the 40dB, but Assumed to be greater the 40dB, but

varies between patientsvaries between patients Masking used to eliminate this Masking used to eliminate this

confounding factorconfounding factor

PTA limitationsPTA limitations

PTA in NOT always a ‘Gold Standard’ PTA in NOT always a ‘Gold Standard’ and infallibleand infallible

Limited by : patient, audiologist and Limited by : patient, audiologist and equipmentequipment

Beware on NOHLBeware on NOHL Try to supplement other simple testsTry to supplement other simple tests

Speech AudiometrySpeech Audiometry

Speech AudiometrySpeech Audiometry Speech Reception Threshold using Speech Reception Threshold using

spondaic wordsspondaic words Standardized word listsStandardized word lists Ascending series of presentationAscending series of presentation Minimum intensity at which 50% of words Minimum intensity at which 50% of words

are repeated correctlyare repeated correctly Excellent speech discrimination in Excellent speech discrimination in

conductive hearing loss patientsconductive hearing loss patients Poor speech discrimination in cochlear Poor speech discrimination in cochlear

hearing loss patientshearing loss patients Poorest speech discrimination in Poorest speech discrimination in

retrocochlear hearing loss patientsretrocochlear hearing loss patients

Imepedence AudiometryImepedence Audiometry

(Tympanometry + stapedial reflex)

Tympanometry

Definition:Definition:

Tympanometry is an Tympanometry is an electronic and acoustic electronic and acoustic measurement technique to measurement technique to assess middle ear statusassess middle ear status

Combined with otoscopy, it is Combined with otoscopy, it is an objective, fast, and highly an objective, fast, and highly accurate way to rule out accurate way to rule out outer and middle ear outer and middle ear pathologypathology

Principles of TympanometryPrinciples of Tympanometry

Introduces a pure tone into ear canal through Introduces a pure tone into ear canal through 3-3-function probe tipfunction probe tip

ManometerManometer (pump) varies air pressure against TM (controls (pump) varies air pressure against TM (controls mobility)mobility)

SpeakerSpeaker introduces 220Hz probe toneintroduces 220Hz probe tone MicrophoneMicrophone measures loudness in ear canalmeasures loudness in ear canal

TympanometryTympanometry

Janet Stockard Sullivan 2003

Here’s how it works...Here’s how it works...

These 5 second motion video otomacroscopy (MVOM) samples resent a view of a 58 year male right tympanic membrane during tympanometry.

The patulous pars flaccida was ejected at the outset of recording from a prior tympanometric trial.

The Middle Ear Analyzer was set to run from +400 daPa though -600 daPa. MVOM and tympanograms were video-captured 15 f/s .

The time lines between videos are only roughly coincident.

The negative slope of the tympanogram corresponds to the period of rapid pars flaccida ejection.

videosvideos

Taken from---http://www.rcsullivan.com/www/tympavi.htm

Normal tympanogram (Type A)Normal tympanogram (Type A)

Peak at 0 daPaPeak at 0 daPa

Best movement Best movement of drum when of drum when no extra no extra pressure on pressure on either side of either side of TMTM

Other Type A tympanogramsOther Type A tympanograms

Peak at 0daPa, but Peak at 0daPa, but unusually high unusually high

amplitudeamplitude

? Ossicular disruption? Ossicular disruption

Peak at 0daPa, but Peak at 0daPa, but unusually low unusually low

amplitudeamplitude

? Stapes fixation? Stapes fixation

Flat tympanogram (Type B)Flat tympanogram (Type B)

No PeakNo Peak

No best TM No best TM movement at movement at any pressureany pressure

Flat tympanogram (Type B)Flat tympanogram (Type B)

When tymp is flat, When tymp is flat,

usually means 1 of 3 usually means 1 of 3 things:things:

1.1. ArtefactArtefact

2.2. Fluid in MEFluid in ME

3.3. PerforationPerforation

Look at EAM vol.Look at EAM vol.

If large = perfIf large = perf

If normal = fluidIf normal = fluid

Negative tympanogram (Type C)Negative tympanogram (Type C)

Peak at < 0daPaPeak at < 0daPa

Best movement Best movement of drum when of drum when negative negative pressure in pressure in EAM thus EAM thus middle ear middle ear pressure must pressure must be less than be less than atmosphericatmospheric

Negative tympanogram (Type C)Negative tympanogram (Type C)

Can be further Can be further divided into:divided into:

C1 – peak C1 – peak between 0 and between 0 and -200 daPa-200 daPa

C2 – peak less C2 – peak less than -200daPathan -200daPa

Acoustic Reflex TestingAcoustic Reflex Testing

The stapedius muscle attaches to the neck of the stapesThe stapedius muscle attaches to the neck of the stapes Upon being triggered by loud sound, contraction of the Upon being triggered by loud sound, contraction of the

stapedius dampens motion of the stapes, reducing stapedius dampens motion of the stapes, reducing effectiveness of the ossicular chain effectiveness of the ossicular chain

In acoustic reflex testing, the probe tip produces a sudden In acoustic reflex testing, the probe tip produces a sudden loud tone and simultaneously records any drop in complianceloud tone and simultaneously records any drop in compliance

If the compliance drops, the tympanometer records the If the compliance drops, the tympanometer records the acoustic reflex as acoustic reflex as presentpresent • Interpret as no conductive component, and not more than Interpret as no conductive component, and not more than

moderately severe hearing lossmoderately severe hearing loss If compliance is not affected, the tympanometer records the If compliance is not affected, the tympanometer records the

reflex as reflex as absentabsent• Subject to wide range of interpretationSubject to wide range of interpretation

Interpreting results of acoustic Interpreting results of acoustic reflex testing: Summaryreflex testing: Summary

Reflex present = probable normal middle ear function Reflex absent = possible middle ear problem, severe sensorineural hearing loss, or several other possible explanations

OTOACOUSTIC EMISSIONSOTOACOUSTIC EMISSIONS

OAE’sOAE’s

They are low intensity sounds They are low intensity sounds produced by outer hair cells of a produced by outer hair cells of a normal cochleanormal cochlea

Can be elicited by a very sensitive Can be elicited by a very sensitive microphone placed in EACmicrophone placed in EAC

Absent when OHC are damagedAbsent when OHC are damaged Thus serve to test cochlear Thus serve to test cochlear

functioningfunctioning

Outer hair cellsOuter hair cells

Basilar membraneBasilar membrane

PerilymphPerilymph

Oval windowOval window

OssiclesOssicles

Tympanic membraneTympanic membrane

EACEAC

OAE’s

spontaneous evoked

Transient(click)

Distortion product(paired tones)

Spontaneous OAESpontaneous OAE

They are present in healthy normal They are present in healthy normal hearing personshearing persons

When hearing loss does not exceeds When hearing loss does not exceeds 30 dB30 dB

May be absent in 50% of normal May be absent in 50% of normal personspersons

Transient Evoked OAETransient Evoked OAE

-Evoked by clicks-Evoked by clicks

-Clicks are presented at 80-85 dB-Clicks are presented at 80-85 dB

Distortion Product OTOACOUSTIC Distortion Product OTOACOUSTIC EMISSIONSEMISSIONS

USES of OAE’sUSES of OAE’s

As a screening test for neonatesAs a screening test for neonates Distinguish cochlear from Distinguish cochlear from

retrocochlear HLretrocochlear HL To test hearing in meantally To test hearing in meantally

challanged and uncooperative challanged and uncooperative individuals after sedationindividuals after sedation

(Note- sedation doesn’t interferes with OAE’s)(Note- sedation doesn’t interferes with OAE’s)

Brainstem Evoked Response Brainstem Evoked Response AudiometryAudiometry

(BERA)(BERA)

BERABERABrainstem Evoked Response AudiometryBrainstem Evoked Response Audiometry

DefinitionDefinition

Bera is an objective way of Bera is an objective way of eliciting brain stem potentials in eliciting brain stem potentials in response to audiological click response to audiological click stimuli. These waves are stimuli. These waves are recorded by electrodes placed recorded by electrodes placed over the scalp.Thisover the scalp.This  investigation investigation was first described by Jewett and was first described by Jewett and Williston in 1971.Williston in 1971.

The standard electrode The standard electrode configurationconfiguration

--a non --a non inverting inverting electrode electrode over the over the vertex of the vertex of the headhead

--an inverting electrodes placed over --an inverting electrodes placed over the ear lobe or mastoid prominence. the ear lobe or mastoid prominence.

--One more earthing electrode is placed --One more earthing electrode is placed over the foreheadover the forehead

Cochlear nerves

Cochlear nucleus

Superior olivary complex

Nulclei of lateral lemniscus

 Inferior colliculus 

Uses of BERA:Uses of BERA:

1. It is an effective screening tool for 1. It is an effective screening tool for evaluating cases of deafness due to evaluating cases of deafness due to retrocochlear pathology i.e. (Acoustic retrocochlear pathology i.e. (Acoustic schwannoma). An abnormal BERA is an schwannoma). An abnormal BERA is an indication for MRI scan.indication for MRI scan.

2. Used in screening newborns for deafness2. Used in screening newborns for deafness 3. Used for intraoperative monitoring of 3. Used for intraoperative monitoring of

central and peripheral nervous systemcentral and peripheral nervous system 4. Monitoting patients in intensive care units4. Monitoting patients in intensive care units 5. Diagnosing suspected demyelinated 5. Diagnosing suspected demyelinated

disordersdisorders

BERA findings suggestive of BERA findings suggestive of retrocochlear pathology:retrocochlear pathology:

1. Latency differences between 1. Latency differences between interaural wave 5 (prolonged in interaural wave 5 (prolonged in cases of retrocochlear pathology)cases of retrocochlear pathology)

2. Waves I - V interaural latency 2. Waves I - V interaural latency differences - prolongeddifferences - prolonged

3. Absolute latency of wave V - 3. Absolute latency of wave V - prolongedprolonged

4. Absence of brain stem 4. Absence of brain stem response in the affected earresponse in the affected ear

Criteria for screening newborn Criteria for screening newborn babies using BERA: babies using BERA: 

1. Parental concern about hearing 1. Parental concern about hearing levels in their childlevels in their child

2. Family history of hearing loss2. Family history of hearing loss 3. Pre and post natal infections3. Pre and post natal infections 4. Low birth weight babies4. Low birth weight babies 5. Hyperbilirubinemia5. Hyperbilirubinemia 6. Cranio facial deformities6. Cranio facial deformities 7. Head injury7. Head injury 8. Persistent otitis media8. Persistent otitis media 9. Exposure to ototoxic drugs9. Exposure to ototoxic drugs

A COMPARISONA COMPARISON

BERABERA CERACERA

Recording is made from brain Recording is made from brain

stem potentialsstem potentials Recording is made from cortical Recording is made from cortical

potentialspotentials Click stimulus is used Click stimulus is used Tone stimulus is used Tone stimulus is used

Responses are not frequency Responses are not frequency specific specific

Responses are frequency specific Responses are frequency specific

Can be performed in awake and Can be performed in awake and

restless patientsrestless patients The patient must lie still through The patient must lie still through

out the processout the process Responses begin after 1 - 10 Responses begin after 1 - 10 milliseconds after stimuli milliseconds after stimuli

Response begins after 50 - 300 Response begins after 50 - 300 milliseconds after stimulation milliseconds after stimulation

Suitable for even young children Suitable for even young children Unsuitable for children Unsuitable for children

ElectrocochleographyElectrocochleography

Electrocochleography setupElectrocochleography setup

The recording electrode is a thin needle passed through the tympanic membrane onto the promontory under L/A or G/A

Non invasive

Electrode placed on TM

Invasive

ECochGECochG

It measures electrical potentials It measures electrical potentials arising in the cochlea and VIII nerve arising in the cochlea and VIII nerve in response to auditory stimuli within in response to auditory stimuli within first 5 millisecfirst 5 millisec

Response is in the form of Cochlear Response is in the form of Cochlear microphonics, Summation potential microphonics, Summation potential and Action potentialsand Action potentials

Final ThoughtFinal Thought

Tests are not infallible, they are only as good as those taking, administering and interpreting them…

A slideshow presentation A slideshow presentation

Prepared byPrepared by

Dr. ZEESHAN AHMADDr. ZEESHAN AHMADunder guidance ofunder guidance of

DR(Prof)CHANDRA SHEKHARDR(Prof)CHANDRA SHEKHAR(Head ENT deptt)(Head ENT deptt)

THANK YOUTHANK YOU