Ramsay Hunt syndrome mimicking intracanalicular acoustic neuroma on contrast-enhanced MR.

A 46-year-old woman had left-sided otalgia, tinnitus , hearing loss, and headaches centered on the left eye. Left peripheral facial nerve palsy occurred 2 days later, and the facial pain worsened. Brainstem auditory evoked potentials, usually abnormal in cases of acoustic neuroma, were normal. An MR study with TR = 2000, dual echo, and a 1 0-mm axial screening procedure showed only a vague asymmetric increase in signal intensity in the left internal auditory canal , possibly attributable to volume-averaging differences on the two sides. A second study with TR = 1000, TE = 40, coronal images, and 5-mm slice thickness was done after a standard dose of gadopentetate dimeglumine was given IV. Good definition of the right and left internal auditory canals was seen on two adjacent sections, and bright enhancement was seen within the canal on the symptomatic left side (Fig. 1A). The patient 's pain lessened after she began prednisone therapy. Twelve days after her initial office visit , she noticed several small vesicles in her left external ear. After a week of therapy with acyclovir, some improvement in seventh nerve function was seen. The patient returned for a follow-up MR study 4 months after the initial examination . At that time, she said that the left-sided facial weakness had improved "95%" and that her hearing was better. Repeat contrastenhanced coronal MR (1 000/40, 5-mm slice thickness) showed only slight residual enhancement on the left side (Fig . 1 B).