Otoacoustic Emissions In Patients With Tinnitus And Normal Hearing

Objectives:We studied the characteristics of Distortion productotoacoustic emissionsins(DPOAE) ,spontaneous otoacoustic emissions(SOAE) , transiently evoked otoacoustic emissions (TEOAE) in patientswith complaints of tinnitus and normal hearing ,explored causes of tinnitusand the relationship between tinnitus and otoacoustic emissions (OAE) . Methods:We evaluated 94 patients (155ears) with tinnitus. Theinclusion criterion that was to have thresholds of 25 dB or less in eachfrequency at tonal audiometry. DPOAE, TEOAE ,SOAE were performedin each patient respectively. History of occupational noise exposition waseliminated. Results: 1 . The incidences of DPOAE,TEOAE,SOAE in study groupwere87.1%,46.5%,23.8% respectively. 2.There was no correlation between the tone, loudness of tinnitus andthe frequency ,intensity of SOAE. 3.65.1% the DPOAE-gram presented lower amplitude or was absentin the frequency of tinnitus matched. 42.6%(66/155) had OAE absent orlowered in one or more higher frequencies, and there is obvious differencein the slope of I/O-gram between the study and control group;34.8%(54/155) had OAE absent or lowered in one or more lowerfrequencies, and there is no obvious difference in the slope of I/O-grambetween the study and control group. Conclusions:One of the theories that try to explain the pathogenesisof tinnitus is the damage of external hairy cells (EHC) in earlier stage.Potential pathological change in the middle ear is another factor. So OAEcould reflect cochlear lesion in early stage. DPOAE I/O-functions allow adifferentiation between middle and inner ear dysfunction.