title: Coiling of intracranial aneurysms: a systematic review on initial occlusion and reopening and retreatment rates.
abstract: OBJECTIVE
  The proportion of incompletely occluded aneurysms after coiling varies widely between studies. To assess overall outcome of coiling, we systematically reviewed the literature to determine initial occlusion, reopening, and retreatment rates of coiled aneurysms according to predefined criteria and subgroups.
  
  
  METHODS
  We searched PubMed and EMBASE (January 1999 to September 2008) for studies of >50 coiled aneurysms. Two reviewers independently extracted data. We grouped studies reporting on only ruptured aneurysms, posterior circulation aneurysms, and studies with large proportions of aneurysms >10 mm to assess possible determinants for incomplete occlusion, reopening, and retreatment.
  
  
  RESULTS
  Forty-six studies totalling 8161 coiled aneurysms met inclusion criteria. Immediately after coiling, 91.2% (95% CI, 90.6% to 91.9%) of the aneurysms were adequately occluded. Aneurysm reopening occurred in 20.8% (95% CI, 19.8% to 21.9%) and retreatment was performed in 10.3% (95% CI, 9.5% to 11.0%). Reopening rate was lower in studies reporting on ruptured aneurysms only compared with all studies (11.4% versus 20.8%; relative risk, 0.55; 95% CI, 0.47 to 0.64) and higher in studies focusing on posterior circulation aneurysms compared with studies with >85% anterior circulation aneurysms (22.5% versus 15.5%; relative risk, 1.5; 95% CI,1.2 to 1.7). Regression analysis showed higher retreatment rates with increasing proportion of aneurysms >10 mm (beta=0.252; 95% CI, 0.073 to 0.432). We could not find a relation between reopening and type of coils used.
  
  
  CONCLUSIONS
  At follow-up, one fifth of all coiled intracranial aneurysms shows reopening of which half is retreated. Possible risk factors for aneurysm reopening are location in the posterior circulation and size >10 mm. To confirm our findings, a meta-analysis on individual well-reported patient data is desirable.
authors.affiliation: Department of Radiology, Academic Medical Center Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. S.P.Ferns@amc.uva.nl
authors.forename: Sandra P
authors.initials: SP
authors.lastname: Ferns
authors.forename: Marieke E S
authors.initials: ME
authors.lastname: Sprengers
authors.forename: Willem Jan
authors.initials: WJ
authors.lastname: van Rooij
authors.forename: Gabriël J E
authors.initials: GJ
authors.lastname: Rinkel
authors.forename: Jeroen C
authors.initials: JC
authors.lastname: van Rijn
authors.forename: Shandra
authors.initials: S
authors.lastname: Bipat
authors.forename: Menno
authors.initials: M
authors.lastname: Sluzewski
authors.forename: Charles B L M
authors.initials: CB
authors.lastname: Majoie
mesh_terms: D020785:Central Nervous System Vascular Malformations / Q000453:epidemiology / Q000503:physiopathology / Q000601:surgery*; D002548:Cerebral Revascularization / Q000295:instrumentation* / Q000379:methods; D002986:Clinical Trials as Topic / Q000639:trends; D004621:Embolization, Therapeutic / Q000295:instrumentation / Q000379:methods; D006801:Humans; D002532:Intracranial Aneurysm / Q000453:epidemiology / Q000503:physiopathology / Q000601:surgery*; D019233:Retreatment; D016896:Treatment Outcome