Stereotactic radiation therapy for large vestibular schwannomas.

Abstract

To evaluate the morbidity and tumor-control rate in the treatment of large vestibular schwannomas (VS) after stereotactic radiation therapy in our institution. Twenty-five consecutive patients (17 men, 8 women) with large VS (diameter 3.0 cm or larger), treated with stereotactic radiotherapy (SRT) or stereotactic radiosurgery (SRS) between 1992 and 2007, were retrospectively studied after a mean follow-up period of three years with respect to tumor-control rate and complications. Actuarial 5-year maintenance of pre-treatment hearing level probability of 30% was achieved. Five of 17 patients suffered permanent new facial nerve dysfunction. The actuarial 5-year facial nerve preservation probability was 80%. Permanent new trigeminal nerve neuropathy occurred in two of 15 patients, resulting in an actuarial 5-year trigeminal nerve preservation probability of 85%. Tumor progression occurred in four of 25 (16%) patients. The overall 5-year tumor control probability was 82%. Increased morbidity rates were found in patients with large VS treated with SRT or SRS compared to the published series on regular sized VS and other smaller retrospective studies on large VS.