Gamma knife radiosurgery for the treatment of cavernous sinus meningiomas.

OBJECTIVE We report on the efficacy of gamma knife radiosurgery for cavernous sinus meningiomas. METHODS Between January 1994 and December 1999, we used gamma knife radiosurgery for the treatment of 43 patients with cavernous sinus meningiomas. Forty-two patients were followed up for a mean of 49.4 months (range, 18-84 mo). The patients' average age was 55 years (range, 18-81 yr). Twenty-two patients (52%) underwent operations before radiosurgery, and 20 patients (48%) underwent radiosurgery after the diagnosis was made by magnetic resonance imaging. The tumor volumes ranged from 1.2 to 101.5 cm(3) (mean, 14.7 cm(3)). The tumors either compressed or were attached to the optic apparatus in 17 patients (40.5%). The marginal radiation dose was 8 to 15 Gy (mean, 11 Gy), and the optic apparatus was irradiated with 2 to 12 Gy (mean, 6.2 Gy). Three patients with a mean tumor diameter greater than 4 cm were treated by two-stage radiosurgery. RESULTS Thirty-eight patients (90.5%) demonstrated tumor growth control during the follow-up period after radiosurgery. Tumor regression was observed in 25 patients (59.5%), and growth was unchanged in 13 patients (31%). Regrowth or recurrence occurred in four patients (9.5%). The actual tumor growth control rate at 5 years was 92%. Only one patient (2.4%) experienced regrowth within the treatment field; in other patients, regrowth occurred at sites peripheral to or outside the treatment field. Twelve patients (28.6%) had improved clinically by the time of the follow-up examination. None of the patients experienced optic neuropathy caused by radiation injury or any new neurological deficits after radiosurgery. CONCLUSION Gamma knife radiosurgery may be a useful option for the treatment of cavernous sinus meningiomas not only as an adjuvant to surgery but also as an alternative to surgical removal. We have shown it to be safe and effective even in tumors that adhere to or are in close proximity to the optic apparatus.