title: Gamma Knife surgery for hemifacial spasm related to cerebellopontine angle tumors.
abstract: OBJECTIVE
  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.
authors.affiliation: School of Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Cheng-Siu
authors.initials: CS
authors.lastname: Chang
authors.forename: Chun-Chao
authors.initials: CC
authors.lastname: Chuang
authors.forename: Ming-Fan
authors.initials: MF
authors.lastname: Wu
authors.forename: Wen-Shan
authors.initials: WS
authors.lastname: Liu
authors.forename: Hsien-Tang
authors.initials: HT
authors.lastname: Tu
authors.forename: Chuan-Fu
authors.initials: CF
authors.lastname: Huang
mesh_terms: D002530:Cerebellopontine Angle / Q000473:pathology / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D019569:Hemifacial Spasm / Q000209:etiology / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008579:Meningioma / Q000150:complications / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D009442:Neurilemmoma / Q000150:complications / Q000473:pathology / Q000601:surgery*; D009464:Neuroma, Acoustic / Q000150:complications / Q000473:pathology / Q000601:surgery*; D016634:Radiosurgery / Q000295:instrumentation*; D016896:Treatment Outcome; D047368:Tumor Burden