Drilling and control of the internal auditory canal by fixed endoscope.

Preservation of vestibular structures, particularly the posterior semicircular canal, is essential to ensure hearing preservation in addition to complete tumour resection during retrosigmoid surgical resection of a vestibular schwannoma. Drilling of the internal auditory canal (IAC) is a delicate step, during which these structures can be accidentally perforated. The orientation of the IAC results in the formation of poorly visible zones that can predispose to perforation of these structures when drilling is performed with a microscope. Hand-held endoscopy exposes all of the operative field, but immobilizes one of the surgeon's hands, making this surgery even more delicate. Fixed endoscopy is a solution that gives the surgeon greater freedom of movement, while ensuring precise control of the surgical procedure. It allows identification and avoidance of vestibular structures, while allowing resection as close as possible to the tumour. The schwannoma can be entirely cleaved when the fundus of the IAC is correctly controlled, while sparing the facial and cochlear nerves.