title: Is stereotactic radiosurgery the best treatment option for patients with a radiosurgery-based arteriovenous malformation score ≤ 1?
abstract: OBJECTIVE
  The best management of patients with brain arteriovenous malformations (BAVM) is controversial. The radiosurgery-based arteriovenous malformation (AVM) score (RBAS) was developed to predict outcomes for patients with BAVM having stereotactic radiosurgery (SRS).
  
  
  METHODS
  The RBAS is calculated for patients with BAVM having SRS at our center as part of our prospectively maintained SRS database (RBAS = [0.1] [AVM volume; cm(3)] + [0.02] [patient age; years] + [0.5] [AVM location; 0 = cerebral/cerebellar hemispheres/corpus callosum, 1 = basal ganglia/thalamus/brainstem]). Review of the SRS database from 1990 to 2009 identified 80 patients with a RBAS ≤1 and at least 1 year of follow-up. The primary end point of the study was a decline in modified Rankin Score. The mean follow-up after SRS was 68 months (range, 12-133).
  
  
  RESULTS
  The mean patient age was 25.2 years (range, 7-44). Seventy-six patients (95%) had superficially located BAVMs; the mean BAVM volume was 2.3 cm(3) (range, 0.1-8.0). The mean RBAS was 0.76 (range, 0.21-1.00). The patients' MRS before SRS was 0 (n = 52, 65%), 1 (n = 24, 30%), 2 (n = 3, 4%), and 3 (n = 1, 1%). BAVM obliteration was confirmed in 92% of patients with follow-up beyond 3 years (70/76; 95% confidence interval 84%-97%). No patient had a hemorrhage or a radiation-related complication after SRS. The observed rate of modified Rankin Score decrease after SRS was 0% (0/80; 95% confidence interval 0%-6%).
  
  
  CONCLUSIONS
  SRS provided a high rate of obliteration at very low risk for patients with BVAM with a RBAS ≤1. Patient outcomes after SRS are likely equivalent to resection for younger patients with small-volume BAVM who do not require a craniotomy for clot removal.
authors.affiliation: Department of Neurological Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Burrow
authors.affiliation: Department of Neurological Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota, USA; Department of Otorhinolaryngology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Link
authors.affiliation: Department of Neurological Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota, USA; Department of Radiation Oncology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA. Electronic address: pollock.bruce@mayo.edu.
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Pollock
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D023381:Endpoint Determination; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000473:pathology / Q000601:surgery*; D008297:Male; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
keywords: Arteriovenous malformation; Grading scale; Stereotactic radiosurgery