Cochlear Implantation in a Patient with Intractable Tinnitus: A Case Report of an Endoscope-Assisted Approach.

Preservation of residual hearing and vestibular function is a crucial factor in cochlear implantation (CI), especially in patients with residual low-frequency hearing thresholds. We report a case of a patient who underwent unilateral endoscope-assisted CI with a challenging surgical view following rigorous posterior tympanotomy. A 53-year-old male presented with left-sided intractable tinnitus due to sudden sensorineural hearing loss that had occurred 10 years prior. Due to the abnormal location of the round window (RW), which was far more posterior and inferior than usual and impeded insertion of the electrode using the conventional RW approach, endoscope-assisted CI was performed. Pure-tone audiometry at 3 months after CI revealed satisfactory hearing thresholds. Furthermore, there was alleviation of the left-sided tinnitus, which was indicated by a marked decrease in both the subjective visual analog scale loudness and Tinnitus Handicap Inventory scores. With proper indications, we strongly recommend applying the RW approach with endoscopic assistance over conventional bony cochleostomy for the preservation of low-frequency hearing thresholds in cases where RW visualization is insufficient following posterior tympanotomy.