title: Stereotactic radiosurgery for trigeminal schwannomas.
abstract: OBJECTIVE
  Traditionally trigeminal schwannomas (TS) have been treated microsurgically; however, this is often associated with significant morbidity, and complete excision remains a challenge. Stereotactic radiosurgery (SRS) offers a minimally invasive alternative in treating TS. We report on our cumulative experience of using SRS in the treatment of TS.
  
  
  METHODS
  Seventy-four TS patients (four with NF2) were treated with SRS using the Leksell Gamma Knife. Mean age (±1 SD) at treatment was 47.1 (15.5) years with a mean interval between presentation and treatment of 30.9 months. Thirty (40.5%) patients had undergone previous surgery on average 47.3 months prior to SRS. The average target volume was 5.3 cm(3) (range 0.4-19.9 cm(3)) and was treated with a mean prescription dose of 16.4 (3.9) Gy to the tumour margin.
  
  
  RESULTS
  Average follow-up was 48.2 months (range 6-168 months). Tumour size remained static in 58 (78.4%) patients and showed radiological evidence of shrinkage in 11 (14.9%). Tumour progression occurred in five (6.6%) patients on average 40 months after SRS (range 12-108). Progression-free survival (PFS) for all patients was 98.5% at 1 year, 92.7% at 5 years and 79.4% at 10 years. Log-rank analysis indicated a significantly worse outcome for NF2 patients (p = 0.001) who demonstrated a PFS of 100% at 1 year and 50% at 5 years. Seven patients developed adverse radiation effects whilst improvements in pre-treatment cranial nerve dysfunction were achieved in eight patients.
  
  
  CONCLUSIONS
  SRS is an effective treatment option in patients with residual or newly diagnosed TS. In view of the results of this study we would advocate a more front-line role for the Gamma Knife in the treatment of this tumour group.
authors.affiliation: The National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital, Sheffield, S10 2JF, UK.
authors.forename: John
authors.initials: J
authors.lastname: Yianni
authors.forename: Eduard Bogdan
authors.initials: EB
authors.lastname: Dinca
authors.forename: Jeremy
authors.initials: J
authors.lastname: Rowe
authors.forename: Matthias
authors.initials: M
authors.lastname: Radatz
authors.forename: Andras A
authors.initials: AA
authors.lastname: Kemeny
mesh_terms: D003390:Cranial Nerve Neoplasms / Q000175:diagnosis / Q000601:surgery*; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D020433:Trigeminal Nerve Diseases / Q000175:diagnosis / Q000601:surgery*