Surgical anatomy of transcanal endoscopic approach to the tympanic facial nerve.

OBJECTIVES/HYPOTHESIS: Until recently, tympanic facial nerve surgery had been performed using microscopic approaches, but in recent years, exclusive endoscopic approaches to the middle ear have increasingly been used, particularly in cholesteatoma surgery. The aim of this report was to illustrate the surgical anatomy of the facial nerve during an exclusive endoscopic transcanal approach.

STUDY DESIGN

Retrospective video review of cadaveric dissections and operations on living patients in a tertiary university referral center.

METHODS

Between November 2008 and July 2010, a total of 12 endoscopic cadaveric dissections were performed by an exclusive endoscopic transcanal approach. All dissections were recorded and stored in a database. In July 2010, video recordings from those dissections were reviewed, and the anatomic variations and accessibility of the tympanic facial nerve were studied and noted. Two further video recordings from living patients affected by middle ear chronic disease were also included in our study.

RESULTS

In all 14 subjects, the transcanal endoscopic approach guaranteed direct access to the entire tympanic segment of the facial nerve after ossicular chain removal, allowing decompression of the nerve from the geniculate ganglion and the greater petrosal nerve to the second genu of the facial nerve. As in microscopic techniques, the cochleariform process and transverse crest (cog) may represent useful landmarks.

CONCLUSIONS

The tympanic facial nerve can be thoroughly visualized by an exclusive endoscopic transcanal approach, even in poorly accessible regions such as the second genu and geniculate ganglion. Further clinically based reports may strengthen our preliminary results.