Gamma Knife surgery for hemifacial spasm related to cerebellopontine angle tumors Clinical article

Object. Most cases of tumor-related hemifacial spasm (HFS) are treated by open surgery. The authors report the effects of Gamma Knife surgery (GKS) on benign tumor-related HFS at a mean follow-up time of 84 months. Methods. Between 2000 and 2011,6 patients (5 women and 1 man) harboring single tumors of the cerebellopontine angle (4 meningiomas and 2 vestibular schwannomas [VSs]) and experiencing HFS underwent GKS as a primary treatment. The mean age of the patients at the time of radiosurgery was 52.7 years (range 45-60 years). The patients' tumors lay within the radiosurgical target area. In the 4 cases of meningioma, the mean radiosurgical treatment volume was 5.3 cm(3) (range 1.2-9.6 cm(3)), and the mean radiosurgical tumor margin dose was 14.1 Gy (range 12-18 Gy); in the 2 cases of VS, the treatment volume was 2.5 cm(3) in 1 patient and 11.2 cm(3) in the other, and the margin doses were 11.5 and 12 Gy, respectively. The mean duration of HFS symptoms was 15.5 months (range 3-36 months). Results. The mean follow-up period was 84 months (range 40-110 months). Overall, 4 (66%) of the 6 patients experienced complete relief from HFS without medication after GKS and 1 patient obtained a good outcome. The mean time for improvement to be realized was 12.6 months (range 3-24 months). Only 1 patient failed to experience relief from HFS, and coincidentally, the tumor did not shrink in that case. In all 6 patients (100%), tumor growth was controlled at a mean follow-up of 56 months after GKS: in 5 patients the tumor had decreased in size and in the other patient the tumor size remained unchanged. No new neurological deficit was noted after GKS, and 1 patient with facial numbness reported improvement after tumor shrinkage. Conclusions. Gamma Knife surgery appears to be effective in treating benign tumor related HFS and in controlling tumor growth. A reduction in tumor volume is related to spasm improvement. Although a time latency for spasm relief is associated with GKS, minimal side effects are expected. (http://thejns.org/doi/abs/10.3171/2012.7.GKS12999)