Facial nerve neuroma.

A 39-year-old woman was seen in our clinic for evaluation of a 9-month history of progressive fight facial weakness. More recently, she had noted a decrease in hearing on her right side, as well. On initial examination, she was noted to have a House-Brackmann grade 4/6 fight facial weakness. Examination of the ear canal detected a smooth, tan mass behind the posterior half of the tympanic membrane; the mass caused the eardrum to bulge outwardly (figure). Magnetic resonance imaging with gadolinium contrast showed an enhancement of the facial nerve extending from the area of the geniculate ganglion to its intraparotid segment.

The patient underwent surgery via a combined transmastoid-middle fossa approach. A facial nerve schwannoma was seen extending from the geniculate ganglion to the parotid gland and terminating just proximal to the pesanserinus; the schwannoma was completely removed. The tumor was removed without difficulty; the damaged incus and the head of the malleus were also removed. A sural nerve graft was placed from the labyrinthine segment of the facial nerve to the intraparotid stump. The head of the malleus was used as an interposition graft between the intact tympanic membrane and the stapes capitulum.

Facial nerve schwannomas are rare, accounting for less than 1% of all intratemporal mass lesions. They tend to grow slowly, and they are often asymptomatic until they have reached larger dimensions. The most common symptoms are hearing loss and facial paresis.

Because of their benign nature and slow growth, these tumors can be observed until significant symptoms develop. Even in the best of circumstances, however, cable grafting after excision will result in a House-Brackmann grade of only 4/6.

Peter A. Weisskopf, MD; Derald E. Brackmann, MD