Facial nerve decompression complications.

Every structure contained within the temporal bone in close proximity to the facial nerve is at risk during intratemporal bone surgery on the facial nerve. We present a review of the causes of injuries to these structures and of ways to prevent such injuries. This review includes information drawn from pertinent literature, from the author's experience managing 139 patients undergoing temporal bone surgery for a variety of facial nerve disorders between 1974 and 1981, from an analysis of 43 of our patients whose hearing was evaluated before transmastoid facial nerve surgery and again 6 months after surgery, and from the experiences of colleagues. We found that the most frequent complication of intratemporal facial nerve surgery is auditory involvement. An air-bone gap of 15 dB or greater was noted in 14% of the 43 patients studied and a sensorineural loss, primarily at the 4000 and 8000 cycles, occurred in 51% of these patients. A decrease in discrimination of 15% or greater was noted in 7% of patients, and a shift in speech reception threshold of 15 dB or greater was noted in 16% of the patients. Twelve percent of the patients had tinnitus following surgery and 5% required a hearing aid as a result of a combined sensorineural and conductive hearing loss which occurred in their better hearing ear as a result of surgery. Structures less commonly injured during transmastoid decompression of the facial nerve included the facial nerve itself, the chorda tympani nerve, the balance function of the labyrinth, the cochlea, the ossicles, the sigmoid sinus and superior petrosal vein, the middle meningeal artery and the stylomastoid artery, the dura, and the brain. We review all of these complications, as well as discuss the incidence of cerebrospinal fluid leak and infection which also may result from this type of surgery.