Vestibular findings after stereotactic radiosurgery in acoustic neurinoma

Abstract

Preoperative and postoperative vestibular function was determined in 9 patients with acoustic neurinoma treated by stereotactic radiosurgery with a gamma unit at Tokyo University Hospital. All of the patients had good vestibular function (CP ≤ 50%) before radio-surgery. Seven patients lost the caloric response within 12 months after radiosurgery. When the caloric response diminished, we found symptoms and signs of vestibular disturbance. On the other hand, the hearing level was relatively well preserved. The difference in the degree of preservation between cochlear and vestibular function might be due to the greater vulnerability of the vestibular nerve and its higher dose of irradiation.