title: Stereotactic radiosurgery with and without embolization for intracranial arteriovenous malformations: a systematic review and meta-analysis.
abstract: OBJECTIVE
  The effectiveness and risk of stereotactic radiosurgery (SRS) in the management of partially embolized intracranial arteriovenous malformations (AVMs) remain controversial. The aim of this analysis was to assess current evidence regarding the efficiency and safety of SRS for AVM patients with and without prior embolization.
  
  
  METHODS
  To compare SRS in patients with and without embolization, the authors conducted a meta-analysis of studies by searching the literature via PubMed and EMBASE for the period between January 2000 and December 2013, complemented by a hand search. Primary outcome was the rate of AVM obliteration on a 3-year follow-up angiogram. Secondary outcome was the rate of hemorrhage at 3 years after SRS. Tertiary outcome was permanent neurological deficits related to radiation-induced changes.
  
  
  RESULTS
  Ten studies eligible for analysis included 1988 patients: 593 had undergone embolization followed by SRS and 1395 had undergone SRS alone. The AVM obliteration rate was significantly lower in patients who had undergone embolization followed by SRS than in those who had undergone SRS alone (41.0% vs 59%, OR 0.46, 95% CI 0.37-0.56, p < 0.00001). However, the rates of hemorrhage (7.3% vs 5.6%, OR 1.17, 95% CI 0.74-1.83, p = 0.50) and permanent neurological deficits related to radiation-induced changes (3.3% vs 3.4%, OR 1.41, 95% CI 0.64-3.11, p = 0.39) were not significantly different between the two groups.
  
  
  CONCLUSIONS
  Embolization before SRS significantly decreases the AVM obliteration rate. However, there is no significant difference in the risk of hemorrhage and permanent neurological deficits after SRS alone and following embolization. Further validation by well-designed prospective or randomized cohort studies is still needed.
authors.affiliation: Department of Neurological Surgery, Neurological Institute, University Hospitals Case Medical Center, Cleveland, Ohio.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.forename: Junjie
authors.initials: J
authors.lastname: Zhong
authors.forename: Abhishek
authors.initials: A
authors.lastname: Ray
authors.forename: Sunil
authors.initials: S
authors.lastname: Manjila
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Bambakidis
mesh_terms: D003131:Combined Modality Therapy / Q000379:methods*; D004621:Embolization, Therapeutic; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery*; D016634:Radiosurgery; D016896:Treatment Outcome
keywords: AVM = arteriovenous malformation; SRS = stereotactic radiosurgery; arteriovenous malformation; embolization; outcome; stereotactic radiosurgery