[Selective injury of the vestibular and facial nerves following microvascular decompression procedures for hemifacial spasm: A case report].

Microvascular decompression procedures were carried out to relieve right hemifacial spasm in a 54-year-old man. His facial spasm was satisfactorily cured but he complained of severe vertigo, and slight facial palsy was also shown after the operation. Electronystagmograph disclosed spontaneous horizontal and rotatory nystagmus toward the non-operated (left) side. The postoperative caloric test showed profound dysfunction on the operated side. His hearing was well maintained postoperatively. These findings indicated, in addition to facial nerve injury, that the peripheral portion of the vestibular nerve was selectively damaged by the operative manipulations. It was shown that both the facial and vestibular nerves tended to be injured when the nerve trunk was shifted caudal-to-rostrally due to manipulations in the CP angle. It was stressed that caution should be paid to preserve not only the cochlear but also the vestibular nerve function in cerebellopontine angle manipulations.