title: Linear accelerator-based radiosurgery alone for arteriovenous malformation: more than 12 years of observation.
abstract: OBJECTIVE
  Although radiosurgery is an accepted treatment method for intracranial arteriovenous malformations (AVMs), its long-term therapeutic effects have not been sufficiently evaluated, and many reports of long-term observations are from gamma-knife facilities. Furthermore, there are few reported results of treatment using only linear accelerator (LINAC)-based radiosurgery (LBRS).
  
  
  METHODS
  Over a period of more than 12 years, we followed the long-term results of LBRS treatment performed in 51 AVM patients.
  
  
  RESULTS
  The actuarial obliteration rates, after a single radiosurgery session, at 3, 5, 10, and 15 years were 46.9%, 54.0%, 64.4%, and 68.0%, respectively; when subsequent radiosurgeries were included, the rates were 46.9%, 61.3%, 74.2%, and 90.3%, respectively. Obliteration rates were significantly related to target volumes ≥4 cm(3), marginal doses ≥12 Gy, Spetzler-Martin grades (1 vs other), and AVM scores ≥1.5; multivariate analyses revealed a significant difference for target volumes ≥4 cm(3). The postprocedural actuarial symptomatic radiation injury rates, after a single radiation surgery session, at 5, 10, and 15 years were 12.3%, 16.8%, and 19.1%, respectively. Volumes ≥4 cm(3), location (lobular or other), AVM scores ≥1.5, and the number of radiosurgery were related to radiation injury incidence; multivariate analyses revealed significant differences associated with volumes ≥4 cm(3) and location (lobular or other).
  
  
  CONCLUSIONS
  Positive results can be obtained with LBRS when performed with a target volume ≤4 cm(3), an AVM score ≤1.5, and ≥12 Gy radiation. Bleeding and radiation injuries may appear even 10 years after treatment, necessitating long-term observation.
authors.affiliation: Departments of Neurosurgery and Radiology, Nagasaki University School of Medicine, Nagasaki, Japan. Electronic address: takayuki@nagasaki-u.ac.jp.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsuo
authors.affiliation: Departments of Neurosurgery and Radiology, Nagasaki University School of Medicine, Nagasaki, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Kamada
authors.affiliation: Departments of Neurosurgery and Radiology, Nagasaki University School of Medicine, Nagasaki, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Izumo
authors.affiliation: Departments of Neurosurgery and Radiology, Nagasaki University School of Medicine, Nagasaki, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hayashi
authors.affiliation: Departments of Neurosurgery and Radiology, Nagasaki University School of Medicine, Nagasaki, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Nagata
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery*; D020300:Intracranial Hemorrhages / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010315:Particle Accelerators; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000453:epidemiology*; D016634:Radiosurgery / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D013997:Time Factors; D055815:Young Adult