Clinical analysis of Gamma Knife surgery for trigeminal schwannomas

Abstract

The authors sought to assess the clinical effect of Gamma Knife surgery (GKS) for trigeminal schwannomas. Between December 1994 and December 2003, 69 patients with trigeminal schwannomas underwent GKS, and 58 patients were followed up and reviewed at the Beijing Neurosurgical Institute. The mean target volume was 4.6 cm3. The mean peripheral dose was 13.1 Gy, and the mean central dose was 28.3 Gy. The mean radiological follow-up period was 42.5 months. Radiological follow-up demonstrated near-complete disappearance of the tumors in four patients (6.9%), in 34 patients (58.6%) a reduction was seen, in 16 patients (27.6%) no change was observed, and in four patients (6.9%) an enlargement was revealed. The overall tumor control rate was 93.1%. Improvement of presenting neurological symptoms was observed in 28 patients (48.3%), stabilization of presenting neurological symptoms was observed in 23 patients (39.6%), continued progression of presenting neurological symptoms was observed in seven patients (12.1%), and transient cranial nerve dysfunction was observed in six patients (10.4%). Among 13 patients with secondary trigeminal neuralgia, 10 patients had significant improvement or disappearance of trigeminal neuralgia after GKS. Gamma Knife surgery provides an effective and safe primary and/or adjunct treatment for patients with small- to moderate-sized trigeminal schwannomas, with a low risk of iatrogenic cranial neuropathy and great improvement of clinical symptoms.