Effect of Cochlear Hearing Loss on Tone Burst Evoked Stacked Auditory Brainstem Response

Abstract

The auditory brainstem response (ABR) is one of the most useful clinical procedures for the examination of auditory sensitivity and integrity of auditory system. The conventional ABR is not sensitive in detecting small acoustic tumors and small intracanalicular tumors. Stacked tone burst ABR is a new method developed to increase the sensitivity of ABR in detecting small tumours. It has been reported that cochlear hearing loss affects conventional ABR measures. Hence, it is possible that cochlear hearing loss also affects stacked ABR. Also a separate normative data was established for stacked ABR obtained from adding different frequency specific ABRs. In the present study tone burst ABRs for 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz were recorded from 22 ears with cochlear hearing loss and thirty five ears with normal hearing. Stacked ABR was constructed from these tone burst ABRs. The results indicated there is an effect of number of frequencies used for stacking and amplitude of ABR is largest when ABRs for all the four frequencies are stacked. The results also revealed that cochlear hearing loss affects the amplitude of stacked ABR and the reduction in amplitude increases with increase in severity of hearing loss.