《耳鼻喉科学 Otolaryngology》课程教学课件（PPT讲稿）Ear_3、Hearing loss

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