Transient evoked and distortion product otoacoustic emission profile in patients of otosclerosis: a preliminary report.

The aim of this study was to investigate the profile of transient evoked and distortion product otoacoustic emissions in patients of otosclerosis and to assess any change in otoacoustic emission profile after surgical intervention. This prospective study under tertiary referral centre setting included 31 patients suffering from otosclerosis, who underwent surgical intervention in the form of stapedotomy. Air-bone gap on pure tone audiometry, pre-operative profile and postoperative profile of transient evoked and distortion product otoacoustic emissions at 1 month and 3 months were the main outcome measures of the subjects. The patients demonstrated subjective improvement in hearing and significant closure of air-bone gap on pure tone audiometry. There was statistically significant improvement in amplitudes of both transient-evoked and distortion product emissions in the low frequency range, after surgery. Cochran's Q test was applied to compare the statistical significances among preoperative values, 1 month values and 3 months values for the recorded otoacoustic emissions. It was observed that despite significant improvement in hearing, OAEs were not detected in all patients and correlation with behavioural thresholds was poor. As a result of these findings, the following conclusions can be drawn. The profile of otoacoustic emissions in patients of otosclerosis is variable and does not correlate with hearing thresholds. All patients showed improvement in amplitudes of OAEs after surgical intervention and there was further improvement between the followup profile at 1 month and 3 months, but this was not found to be statistically significant. However, further studies with larger number of patients of otosclerosis can perhaps establish baseline profile of the evoked OAEs and the effect of fixation of stapes on reverse transmission of OAEs.