title: Estimating the Risks of Adverse Radiation Effects After Gamma Knife Radiosurgery for Arteriovenous Malformations.
abstract: We evaluated risk factors associated with the development of adverse radiation effects (ARE) after stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVMs).
  
  
  
  We evaluated 755 patients with AVM who underwent a single Gamma Knife SRS procedure with at least a 2-year minimum follow-up. Eighty-seven patients (12%) underwent previous resection and 128 (17%) had previous embolization. The median target volume was 3.6 mL (range, 0.1-26.3 mL). The median margin dose was 20 Gy (range, 13-27 Gy).
  
  
  
  Fifty-five patients (7%) developed symptomatic ARE at a median follow-up of 75 months. The cumulative rates of symptomatic ARE were 3.2%, 5.8%, 6.7%, and 7.5% at 1, 2, 3, and 5 years, respectively. Factors associated with a higher rate of developing symptomatic ARE included larger AVM volume, higher margin dose, larger 12-Gy volume, higher Spetzler-Martin grade, and higher radiosurgery-based score. The rates of developing symptomatic ARE were higher in the brain stem (22%) or thalamus (16%), compared with AVMs located in other brain locations (4%-8%). Nineteen patients (3%) sustained irreversible new neurological deficits related to ARE, and 1 patient died. The rates of irreversible symptomatic ARE were 0.8%, 1.9%, 2.1%, and 2.8% at 1, 2, 3, and 5 years, respectively. The 5-year cumulative rates of irreversible symptomatic ARE were 9.1% in thalamus, 12.1% in brain stem, and 1.4% in other locations.
  
  
  
  The knowledge of ARE risk rates after AVM radiosurgery can assist informed consent for patients with AVM, their families, and healthcare providers.
authors.affiliation: From the Departments of Neurological Surgery (H.K., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), Radiation Oncology (J.C.F.), and the Center for Image-Guided Neurosurgery (H.K., J.C.F., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), University of Pittsburgh School of Medicine, PA. kanoh@upmc.edu.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kano
authors.affiliation: From the Departments of Neurological Surgery (H.K., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), Radiation Oncology (J.C.F.), and the Center for Image-Guided Neurosurgery (H.K., J.C.F., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), University of Pittsburgh School of Medicine, PA.
authors.forename: John C
authors.initials: JC
authors.lastname: Flickinger
authors.affiliation: From the Departments of Neurological Surgery (H.K., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), Radiation Oncology (J.C.F.), and the Center for Image-Guided Neurosurgery (H.K., J.C.F., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), University of Pittsburgh School of Medicine, PA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Tonetti
authors.affiliation: From the Departments of Neurological Surgery (H.K., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), Radiation Oncology (J.C.F.), and the Center for Image-Guided Neurosurgery (H.K., J.C.F., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), University of Pittsburgh School of Medicine, PA.
authors.forename: Alan
authors.initials: A
authors.lastname: Hsu
authors.affiliation: From the Departments of Neurological Surgery (H.K., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), Radiation Oncology (J.C.F.), and the Center for Image-Guided Neurosurgery (H.K., J.C.F., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), University of Pittsburgh School of Medicine, PA.
authors.forename: Huai-Che
authors.initials: HC
authors.lastname: Yang
authors.affiliation: From the Departments of Neurological Surgery (H.K., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), Radiation Oncology (J.C.F.), and the Center for Image-Guided Neurosurgery (H.K., J.C.F., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), University of Pittsburgh School of Medicine, PA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Flannery
authors.affiliation: From the Departments of Neurological Surgery (H.K., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), Radiation Oncology (J.C.F.), and the Center for Image-Guided Neurosurgery (H.K., J.C.F., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), University of Pittsburgh School of Medicine, PA.
authors.forename: Ajay
authors.initials: A
authors.lastname: Niranjan
authors.affiliation: From the Departments of Neurological Surgery (H.K., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), Radiation Oncology (J.C.F.), and the Center for Image-Guided Neurosurgery (H.K., J.C.F., D.T., A.H., H.-c.Y., T.J.F., A.N., L.D.L.), University of Pittsburgh School of Medicine, PA.
authors.forename: L Dade
authors.initials: LD
authors.lastname: Lunsford
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis* / Q000209:etiology*; D011829:Radiation Dosage; D016634:Radiosurgery / Q000009:adverse effects* / Q000639:trends; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: Gamma knife; T2 changes; adverse radiation effects; arteriovenous malformation; complication; radiation necrosis; stereotactic radiosurgery