Endoscopic diving technique for hearing preservation in managing labyrinth-invading cholesteatomas.

PURPOSE: Complete removal of the matrix over the existing fistula in the event of an extensive cholesteatoma with labyrinth invasion can result in total deafness. This study aimed to present a novel method of underwater endoscopic labyrinth dissection using continuous steroid irrigation (CSI) and systemic steroid administration for hearing preservation.
METHODS: The endoscopic diving technique (EDT) was used to dissect semicircular canals, revealing the underwater anatomy of membranous labyrinth structures, in two cadaver temporal bones. EDT with CSI was used in three clinical cases with extensive cholesteatoma.
RESULTS: On cadaver temporal bones, the anatomy of the lateral (LSC), superior (SSC), and posterior membranous semicircular canals with their respective ampullas and common crus was documented. In the first case managed with transcanal EDT, the LSC was eroded across almost its entire length. The fallopian canal was circumferentially eroded at the second genu and part of the mastoid segment. The cholesteatoma matrix was completely removed, and the membranous LSC was preserved. In the second and third cases, we were able to remove the cholesteatoma matrix along the eroded bony semicircular canals while keeping the membranes intact. No sensorineural hearing loss was detected in the postoperative masked pure-tone audiometry at a mean follow-up time of 12 months or cholesteatoma recurrence at the follow-up imaging.
CONCLUSIONS: EDT with CSI can be safely utilized in the course of temporal bone labyrinth dissections and provides advantages during cholesteatoma removal over the eroded labyrinth on preservation of the membranous structures, and thus may help preserve cochlear function.