Evaluation of drill generated acoustic trauma on the non–operated ear following mastoid surgery

Dr. B.V.Chandre Gowda; Dr. Amrita Suzanne Mathew

Volume : IV, Issue : VI, June - 2015

Evaluation of drill generated acoustic trauma on the non–operated ear following mastoid surgery

Dr. B. V. Chandre Gowda, Dr. Amrita Suzanne Mathew

Abstract :

Objectives:To evaluate the effect of mastoid drilling on he� in the contralateral normal ear and to determine the nature and duration of he� loss. Materials and methods:60 consenting adults,aged 18–50years,with unilateral squamosal chronic otitis media with contralateral normal he� preoperatively,undergoing modified radical mastoidectomy(MRM),were included in a prospective observational study.Clinical evaluation,pure tone audiometry(PTA)and relevant investigations were done.Postoperatively,patients underwent PTA on days 1,3,5,7 and 1,3,6months. Results:Mean age was 31.47�3.38 years.Preoperative mean bone conduction(BC) threshold was 8.5�1.9 dB.Mean drilling time was 44.53�10.02 minutes.Postoperatively,high frequency sensorineural he� loss(SNHL) was noted in the nonoperated ear in 79%,23%,9% and 2% of patients on days 1(p<0.001),3,5 and 7 respectively,with mean BC thresholds of 35.58�17.83 dB,17.46�11.13 dB,13.61�9.02 dB and 9.01�4.17dB respectively.100% of patients had normal he� at 1,3 and 6 months. Conclusion: Drill induced noise during mastoidectomy causes temporary high frequency SNHL in the nonoperated ear due to transcranial conduction of viation