Sensorineural high-frequency hearing loss after drill-generated acoustic trauma in tympanoplasty

Tympanoplasty can cause a sensorineural hearing loss by a mechanism of acoustic trauma. Although this lesion appears to be relatively infrequent in clinical practice, we believe that its low apparent incidence is caused when clinicians fail to assess the auditory frequencies above 8000 Hz. Twenty-four patients with normal bone-conduction audiometric thresholds scheduled for tympanoplasty were assessed with an electro-stimulation, bone-conduction high-frequency audiometer which can measure hearing frequencies up to 20 kHz before and after surgery. A measurable hearing loss was found in the upper limits of the audible frequencies in 9 patients (37.5%), and was considered important in 4 of them (16.7%). This hearing loss was recorded above the upper frequency limit of conventional audiometers. The findings in this study indicate that drilling of the temporal bone can impair the hearing level in the high frequencies in a significant number of patients. High-frequency audiometry is a very sensitive tool to assess any damage caused to the inner ear by surgical procedures carried out in the middle ear and temporal bone.