Role of the endoscope in cochlear implantation: A systematic review

Abstract

Objective: To review the role of the endoscope in cochlear implantation (CI).

Methods: MEDLINE, ScienceDirect, Google Scholar and the Cochrane Library databases, as well as other sources, were searched by two independent reviewers. Studies including patients undergoing either exclusively endoscopic or endoscopically assisted CI were eligible for inclusion. Endoscopic CI approaches and postoperative complications were the primary outcomes. Secondary endpoints included the degree of round window (RW) microscopic visualisation according to St Thomas' Hospital classification and type of cochleostomy for electrode insertion in the scala tympani (ST).

Results: Fourteen studies met the inclusion criteria comprising 191 endoscopic or endoscopically assisted CI cases. The endoscope was used for better visualisation of the RW across all included studies, facilitated the insertion of the electrode in the ST and spared a mastoidectomy in a number of cases. No facial nerve palsy was reported in any of the studies. The most common complication was external auditory canal/tympanic membrane tear followed by chorda tympani injury.

Conclusion: The microscopic CI approach is still the gold standard. The endoscope facilitates the recognition of the RW area and leads to successful and safe implantation, particularly in difficult anatomical scenarios, ear malformations and advanced otosclerosis. Endoscopically assisted CI procedures offer the opportunity to avoid a posterior tympanotomy and reduce the risk of facial nerve injury. To date, the lack of long-term data does not permit the widespread adoption of completely endoscopic CI procedures without a mastoidectomy.

Keywords: cochlear implantation; deafness; endoscopy; facial nerve; round window.