[A case of facial nerve neurinoma originated from the cerebellopontine angle portion].

Facial nerve neurinomas are relatively rare and most of them appear at the vertical portion of the facial nerve. Facial nerve neurinoma originated from the cerebellopontine (c-p) angle portion is less frequently reported. A 51-year-old woman was admitted to our hospital complaining of severe headache and nausea. She had had dizziness and unsteady gait for the previous two weeks. She did not complain of hearing disturbance, but otological examination revealed sensorineural deafness. She had no facial palsy. Skull x-ray showed no erosion of the internal auditory canal. Plain CT-scan revealed a large, unenhanced, low-density mass in the right c-p angle cistern. At the time of the operation, this tumor originated from the right facial nerve. Histological diagnosis of this tumor was schwannoma. After the operation, right facial nerve palsy appeared but hardness of hearing was no worse than previously. This tumor seemed to be facial nerve neurinoma in the c-p angle cistern. To the present, 121 facial nerve neurinomas have been reported in the previous literature. Facial nerve neurinomas in the c-p angle cistern, however, have only been reported in 5 cases. The most frequent symptom of facial nerve neurinoma in the temporal bone is facial nerve palsy, but that of facial nerve neurinoma in the c-p angle cistern is hearing loss, as in an acoustic neurinoma. Preoperative diagnosis of facial neurinoma in the c-p angle cistern using neurological symptoms alone is difficult. Furthermore, differential diagnosis from acoustic neurinoma in the c-p angle cistern using only skull x-rays and CT-scanning is also difficult.(ABSTRACT TRUNCATED AT 250 WORDS)