Hearing loss7
1 Hearing loss
HearinglossHearingimpairmentHearingthreshold>25dBDeafness :severe hearing impairment inwhich any type of amplification is not useful2
2 Hearing loss ⚫ Hearing impairment, ⚫ Hearing threshold > 25 dB ⚫ Deafness : severe hearing impairment in which any type of amplification is not useful
Degree of hearing lossWHO,19910-25dBNormal hearing26-40dBMildhearing loss41-60dBModerate hearing loss61-80dBSevere hearing loss>80dBProfound hearing loss3
3 Degree of hearing loss WHO, 1991 Normal hearing 0 – 25dB Mild hearing loss 26-40dB Moderate hearing loss 41-60dB Severe hearing loss 61-80dB Profound hearing loss >80 dB
Types of Hearing lossOrganicMixedNon-organicConductiveOrg +PsychoPsychogenicSensorineural MalingeeringMixed
4 Types of Hearing loss | Organic Non-organic Mixed Conductive Psychogenic Org +Psycho Sensorineural Malingeering Mixed
Types of hearing lossExternal earMiddleearInnerearCochlearnerveSensori-neuraldeafnessConductivedeafnessMixeddeafnessFig.14-1:Types of deafness5
5 Types of hearing loss
ConductivehearinglossDuetointerferenceofconductionofsoundtoreachthecochleaFeature:Rinnetest-usuallynegative(BC>AC)Webertest-lateralizedtoworseearABCtest-normalLowfrequenciesmoreaffectedPuretoneaudiogram-BC>ACABgap>10dBHLnotusually>60dBSpeechdiscriminationisgood6
6 Conductive hearing loss ⚫ Due to interference of conduction of sound to reach the cochlea ⚫ Feature : Rinne test – usually negative (BC > AC) Weber test- lateralized to worse ear ABC test – normal Low frequencies more affected Pure tone audiogram – BC > AC AB gap > 10dB HL not usually > 60dB Speech discrimination is good
Congenital Causesof CHLanotiameatal atresiafixation -foot plate,malleus headossiculardiscontinuitycongenital cholesteatoma
7 Congenital Causes of CHL anotia meatal atresia fixation – foot plate, malleus head ossicular discontinuity congenital cholesteatoma
AcquiredcausesofCHLObstructionof EAC:wax,FB,furuncle,tumourTympanicmembrane-perforationMiddleear-fluid-OME.blood-infection-CSOM,AOM-tumourOssiclesdisruption-trauma,infectionfixation - otospongiosistympanosclerosisEustachiantube block8
8 Acquired causes of CHL ⚫ Obstruction of EAC : wax,FB,furuncle,tumour ⚫ Tympanic membrane – perforation ⚫ Middle ear – fluid – OME, blood - infection –CSOM, AOM - tumour ⚫ Ossicles disruption – trauma, infection fixation - otospongiosis tympanosclerosis ⚫ Eustachian tube block
atresia in the external canal
9 atresia in the external canal
CommoncausesofCHLOtitismedia-CSOM.AOM.OMETympanosclerosisTraumaticperforation of TM,barotraumaOtospongiosisImpactedwax10
10 Common causes of CHL ⚫ Otitis media – CSOM,AOM,OME ⚫ Tympanosclerosis ⚫ Traumatic perforation of TM, barotrauma ⚫ Otospongiosis ⚫ Impacted wax