Preservation of Inner Ear Function in a Case of Vestibular Fistula Caused by Cholesteatoma Using the Underwater Technique.

A 70-year-old male presented with intermittent vertigo, dizziness, and left facial spasms. Otoscopic examination and temporal bone computed tomography revealed extensive cholesteatoma with lateral semicircular canal erosion and a vestibular fistula. Preoperative audiometry demonstrated severe mixed hearing loss with partial preservation of bone conduction thresholds. The patient underwent canal wall-down tympanomastoidectomy using the underwater technique, which involved continuous saline irrigation to stabilize the inner ear environment and minimize perilymph leakage. The fistula site was sealed with soft tissue, bone fragments, and bone pate. Postoperative pure-tone audiometry showed preserved bone conduction thresholds, and stabilometry analysis demonstrated temporary vestibular dysfunction, followed by gradual recovery. One-year postoperative CT confirmed successful closure of the fistula without recurrence. This case highlights the potential of the underwater surgical technique in cholesteatoma-associated vestibular fistulas. By maintaining a stable hydraulic environment and reducing mechanical trauma, this method may contribute to the preservation of cochleovestibular function.