title: Stereotactic Radiosurgery for Arteriovenous Malformations: The Effect of Treatment Period on Patient Outcomes.
abstract: BACKGROUND
  Stereotactic radiosurgery (SRS) has been performed on patients with cerebral arteriovenous malformations (AVMs) for over 40 years.
  
  
  OBJECTIVE
  To evaluate the impact of treatment period on obliteration, intracranial hemorrhage (ICH), and radiation-induced complications (RICs).
  
  
  METHODS
  Retrospective comparison of 381 AVM patients having SRS during a 20-year period (group 1, January 1990 through March 1997, n = 160; group 2, April 1997 through December 2009, n = 221). The median radiological and clinical follow-up after initial SRS was 77 months and 93 months, respectively.
  
  
  RESULTS
  Obliteration was 59.1% at 4 years and 85.1% at 8 years. Obliteration was more common in patients with hemispheric or cerebellar AVMs (P = .001), smaller prescription isodose volume (PIV) (P < .001), and group 1 patients (P < .001). The ICH rate was 7.7% at 4 years and 10.6% at 8 years. ICH was more common in older patients (P = .02), patients with deep AVM (P = .01), and larger PIV (P < .001). There was no difference in the ICH rate between the treatment groups (P = .18). The rate of permanent RICs was 4.4% at 4 years and 8.6% at 8 years. RICs were more common with larger PIVs (P < .001) and group 1 patients (P = .02). There was no difference in the number of patients having obliteration without new deficits between the 2 treatment periods (68.8% vs 73.3%, P = .33).
  
  
  CONCLUSIONS
  Advances in SRS procedures over the past 20 years have resulted in a lower risk of RIC, but fewer patients had AVM obliteration. Increasing the prescription dose for patients with medium- and large-volume AVMs by using current conformal dose-planning techniques may improve the obliteration rate while maintaining a low risk of RICs.
authors.affiliation: Departments of *Neurological Surgery,‡Radiation Oncology, and§Otorhinolaryngology, Mayo Clinic College of Medicine, Rochester, Minnesota.
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Pollock
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Link
authors.forename: Scott L
authors.initials: SL
authors.lastname: Stafford
authors.forename: Yolanda I
authors.initials: YI
authors.lastname: Garces
authors.forename: Robert L
authors.initials: RL
authors.lastname: Foote
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000150:complications / Q000601:surgery*; D020300:Intracranial Hemorrhages / Q000209:etiology; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000009:adverse effects / Q000379:methods*; D019106:Postoperative Hemorrhage / Q000209:etiology; D011832:Radiation Injuries; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult