Herniation of the Facial Nerve in the Middle Ear

A tumor-like herniation of the tympanic portion of the facial nerve discovered during an anatomical dissection is presented to demonstrate its possible surgical hazard through confusion with a peripheral nerve neoplasm. Microscopic examination of serial sections showed all the nerve fibers taking an omega-shaped aberrant course through the herniation. An avascular strand arising from the promontory and crossing the intercrural space of the stapes was observed. It is assumed to be a remnant of the stapedial artery, and its persistence is thought to be responsible for the dehiscence of the facial canal and herniation of the nerve.