Identification of cochlear and Retro cochlear causes in patients with tinnitus

ABSTRACT

This study was designed to identify the possible underlying site of lesion in patients with tinnitus through using Transient Evoked otoacoustic Emissions [TEOAEs], Auditory Brainstem Response [ARR] and Electrocochleography [ECOchG]. Forty subjects complaining of tinnitus were examined. The control group consisted of'24 ears with normal hearing sensitivity not involved with tinnitus. The study group comprised of 36 ears with hearing loss and 20 ears with normal hearing thresholds. TEOAEs revealed that 88.8% of tinnitus ears with hearing loss partially passed or failed to pass the emissions. Interestingly, 20% of tinnitus ears with normal hearing full in the fail to pass category. There was statistically significant difference between control amid study group for absolute latency of wave 1. In ABR test. EcochG results showed that there was no statistically significant difference of the summation potential [SP], action potential [AP] and SP/AP ratio. On individual analysis, two subjects showed increased SP/AP ratio who were finally diagnosed as having Meniere's disease. One subject revealed manifestations of retrocochlear lesion in ABR test results and proved later to have cerebello-pontine angle mass. The combination of TEOAEs, ABR and EcochG is useful to identify site of lesion in tinnitus subjects. EcochG is valuable in diagnosis of endolymphatic subjects. EcochG is valuable in diagnosis of endolymphatic hydrops, ABR for detection of retrocochlear lesion while TEOAEs is very promising for early detection of hidden cochlear pathology