Gamma knife surgery for trigeminal schwannoma

Trigeminal schwannomas are rare intracranial tumors. In the past, resection and radiation therapy were the mainstays of their treatment. More recently, neurosurgeons have begun to use radiosurgery in the treatment of trigeminal schwannomas because of its successful use in the treatment of vestibular schwannomas. In this article the authors evaluate the radiological and clinical outcomes in a series of patients in whom Gamma Knife surgery (GKS) was used to treat trigeminal schwannomas.

Twenty-six patients with trigeminal schwannomas underwent GKS at the University of Virginia Lars Leksell Gamma Knife Center between 1989 and 2005. Five of these patients had neurofibromatosis and one patient was lost to follow up. The median tumor volume was 3.96 cm(3), and the mean follow-up period was 48.5 months. The median prescription radiation dose was 15 Gy, and the median prescription isodose configuration was 50%. There was clinical improvement in 18 patients (72%), a stable lesion in four patients (16%), and worsening of the disease in three patients (12%). On imaging, the schwannomas shrank in 12 patients (48%), remained stable in 10 patients (40%), and increased in size in three patients (12%). These results were comparable for primary and adjuvant GKSs. No tumor growth following GKS was observed in the patients with neurofibromatosis.

Gamma Knife surgery affords a favorable risk-to-benefit profile for patients harboring trigeminal schwannomas. Larger studies with open-ended follow-up review will be necessary to determine the long-term results and complications of GKS in the treatment of trigeminal schwannomas.