title: Complications of Gamma Knife surgery: an early report from 2 Canadian centers.
abstract: OBJECTIVE
  Gamma Knife surgery (GKS) is used to treat benign and malignant brain tumors, arteriovenous malformations, trigeminal neuralgia, and other conditions. Patients experience reduced neurological morbidity from GKS compared with open microneurosurgery, but risks of radiation injury and technical limitations persist. The authors report treatment complications from the early experience of 2 Canadian GKS programs in Toronto and Sherbrooke.
  
  
  METHODS
  In Toronto, a prospective administrative database was searched for adverse events and incomplete treatment administrations. In Sherbrooke, data were acquired by chart review. Patients were accrued until August 1, 2007, and a total of 973 patients were included in this report.
  
  
  RESULTS
  During the radiosurgical procedure, 19 patients (2%) suffered anxiety or syncopal episodes, and 2 patients suffered acute coronary events. Treatments were incompletely administered in 12 patients (1.2%). Severe pain was a delayed complication: 8 patients suffered unexpected headaches, and 9 patients developed severe facial pain. New motor deficits developed in 11 patients, including edema-induced ataxia in 4 and one case of facial weakness after treatment of a vestibular schwannoma. Four patients required shunt placement for symptomatic hydrocephalus, and 16 patients suffered delayed seizures.
  
  
  CONCLUSIONS
  Gamma Knife surgery is a minimally invasive treatment modality for many intracranial diseases. Treatment is not risk free, and some patients will develop complications; these are likely to decrease as institutional experience matures. Expanding availability and indications necessitate discussion of these risks with patients considering treatment.
authors.affiliation: Division of Neurosurgery, University of Toronto, Ontario, Canada.
authors.forename: Shobhan
authors.initials: S
authors.lastname: Vachhrajani
authors.forename: Charbel
authors.initials: C
authors.lastname: Fawaz
authors.forename: David
authors.initials: D
authors.lastname: Mathieu
authors.forename: Cynthia
authors.initials: C
authors.lastname: Ménard
authors.forename: Michael D
authors.initials: MD
authors.lastname: Cusimano
authors.forename: Fred
authors.initials: F
authors.lastname: Gentili
authors.forename: Mojgan
authors.initials: M
authors.lastname: Hodaie
authors.forename: Brendan
authors.initials: B
authors.lastname: Kenny
authors.forename: Abhaya V
authors.initials: AV
authors.lastname: Kulkarni
authors.forename: Normand
authors.initials: N
authors.lastname: Laperriere
authors.forename: Michael
authors.initials: M
authors.lastname: Schwartz
authors.forename: May
authors.initials: M
authors.lastname: Tsao
authors.forename: Mark
authors.initials: M
authors.lastname: Bernstein
mesh_terms: D001927:Brain Diseases / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D002170:Canada; D015331:Cohort Studies; D016208:Databases, Factual; D006801:Humans; D011183:Postoperative Complications / Q000453:epidemiology; D016634:Radiosurgery / Q000009:adverse effects*; D012189:Retrospective Studies; D018570:Risk Assessment; D013997:Time Factors; D016896:Treatment Outcome