Resolution of hemifacial spasm after posterior fossa exploration without vascular decompression.

A 57-year-old woman who had hemifacial spasm on the left side for 5 years underwent exploration of the cerebellopontine angle region for the purpose of microvascular decompression. At operation, however, no artery, vein, or other abnormality was noted at the facial nerve root exit zone. Consequently, the exploration was completed without additional manipulation or the placement of a protective barrier, but the patient awoke from the operation completely free of the spasm. The cause of the hemifacial spasm in this patient could not be explained by the currently predominating vascular compression theory.