title: Long-term outcomes of stereotactic radiosurgery for arteriovenous malformations in the thalamus.
abstract: BACKGROUND
  Arteriovenous malformations (AVMs) in the thalamus carry a high risk of hemorrhage. Although stereotactic radiosurgery (SRS) is widely accepted because of the high surgical morbidity and mortality of these lesions, precise long-term outcomes are largely unknown.
  
  
  OBJECTIVE
  To review our experience with SRS for thalamic AVMs based on the latest follow-up data.
  
  
  METHODS
  Forty-eight patients with thalamic AVMs were treated by SRS using the Leksell Gamma Knife and were followed. Long-term outcomes including the obliteration rate, hemorrhage after treatment, and adverse effects were retrospectively analyzed.
  
  
  RESULTS
  The annual hemorrhage rate before SRS was 14%. The mean follow-up period after SRS was 66 months (range 6-198 months). The actuarial obliteration rate confirmed by angiography was 82% at 5 years after treatment, and the annual hemorrhage rate after SRS was 0.36%. Factors associated with higher obliteration rates were previous hemorrhage (P = .004) and treatment using new planning software (P = .001). Persistent worsening of neurological symptoms was observed in 17% and more frequently seen in patients who were treated using older planning software (P = .04) and a higher margin dose (P = .02). The morbidity rate for patients who received treatment planned using new software with a margin dose not more than 20 Gy was 12%.
  
  
  CONCLUSIONS
  SRS for thalamic AVMs achieved a high obliteration rate and effectively decreased the risk of hemorrhage, with less morbidity compared with other modalities. Longer follow-up to evaluate the risk of delayed complications and the effort to minimize the morbidity is necessary.
authors.affiliation: Department of Neurosurgery, The University of Tokyo Hospital, Bunkyo-ku, Tokyo, Japan. kouga-tky@umin.ac.jp
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Koga
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shin
authors.forename: Keisuke
authors.initials: K
authors.lastname: Maruyama
authors.forename: Atsuro
authors.initials: A
authors.lastname: Terahara
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Saito
mesh_terms: D000293:Adolescent; D000328:Adult; D002543:Cerebral Hemorrhage / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery*; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000209:etiology; D011183:Postoperative Complications / Q000453:epidemiology; D016634:Radiosurgery / Q000009:adverse effects; D012189:Retrospective Studies; D013788:Thalamus / Q000098:blood supply / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult