Stereotactic radiosurgery and fractionated stereotactic radiotherapy for the treatment of nonacoustic cranial nerve schwannomas.

Abstract

To review outcomes after fractionated stereotactic radiotherapy (FSR) and stereotactic radiosurgery (SRS) for nonacoustic cranial nerve schwannomas. We reviewed medical records of 39 patients who received FSR or SRS for nonacoustic cranial nerve schwannomas at our institution during the period from 1996 to 2007. Tumors involved Cranial Nerves V (n = 19), III (n = 2), VI (n = 3), VII (n = 5), IX (n = 2), X (n = 5), and XII (n = 2) and the cavernous sinus (n = 1). Irradiation was performed after partial resection, biopsy, or no previous surgery in 16, 2, and 21 patients, respectively. Twenty-four patients received FSR, delivered in 1.8- to 2.0-Gy fractions to a median dose of 50.4 Gy (range, 45.0-54.0 Gy). Fifteen patients received SRS to a median dose of 12.0 Gy (range, 12-15 Gy). Mild acute toxicity occurred in 23% of the patients. The 2-year actuarial tumor control rate after FSR and SRS was 95%. The median follow-up period was 24 months. Changes in cranial nerve deficits after stereotactic irradiation were analyzed for patients with follow-up periods greater than 12 months (n = 26); cranial nerve deficits improved in 50%, were stable in 46%, and worsened in 4% of the patients. No significant difference was observed for FSR compared with SRS with regard to local control or to improvement of cranial nerve-related symptoms (P = 0.17). SRS and FSR are both well-tolerated treatments for nonacoustic cranial nerve schwannomas, providing excellent tumor control and a high likelihood of symptomatic improvement.