Preservation of cranial nerve function after treatment of acoustic neurinomas with fractionated stereotactic radiotherapy. Preliminary observations in 26 patients.

Twenty-seven acoustic tumors in 26 patients were treated with multiple fractionated linear-accelerator-based stereotactic radiotherapy (SRT). All patients with intact pretreatment facial nerve function with either small or large tumor volumes have thus far experienced no treatment-related facial neuropathy, including 9 patients with a mean follow-up of 22.4 +/- 1.6 months. The incidence of evaluable trigeminal neuropathy was 13%, and in 5 of 7 patients with serviceable pretreatment hearing, audiometry was unchanged in the immediate posttreatment period. Longer follow-up will be necessary to evaluate hearing preservation after SRT. Tumor response with central necrosis was seen in all assessable patients. SRT can be performed for cerebellopontine angle tumors with accuracy and reproducibility. It achieves a biological response similar to single fraction radiosurgery and may lower the incidence of facial and trigeminal neuropathies.