title: Endovascular treatment of very small (3 mm or smaller) intracranial aneurysms: report of a consecutive series and a meta-analysis.
abstract: OBJECTIVE
  We performed a meta-analysis of published studies on the endovascular treatment of very small intracranial aneurysms, including 71 patients treated at our institution.
  
  
  METHODS
  We conducted a computerized MEDLINE search of the literature for reports on the treatment of intracranial aneurysms with a maximum dimension of </=3 mm by using the search terms "small," "tiny," "intracranial aneurysm," "endovascular," and "coil." A total of 7 studies, including our institution's consecutive case series of 71 intracranial aneurysms, were included in this study. We extracted information regarding intraoperative complications, procedural mortality and morbidity, immediate- and long-term angiographic outcomes, and retreatment rate. The meta-analysis was performed with the statistical package Comprehensive Meta-Analysis.
  
  
  RESULTS
  Approximately 61% of the aneurysms in this meta-analysis presented as ruptured, whereas 39% of the aneurysms were unruptured. Procedural rupture rates for very small aneurysms was 8.3% (95% CI, 6.0% to 11.4%). The mortality rate due to procedural rupture was 2.4% (95% CI, 1.2% to 4.7%). The morbidity rate due to thromboembolic complications was 1.9% (95% CI, 0.9% to 3.9%). Subarachnoid hemorrhage within 1 month of treatment occurred in 1.6% (95% CI, 0.6% to 3.7%) of cases. There was no statistically significant difference between unruptured and ruptured aneurysms for any of these outcomes.
  
  
  CONCLUSIONS
  Our meta-analysis suggests that treatment of very small aneurysms is feasible and effective in >90% of treated aneurysms. However, the risk of periprocedural rupture is higher than that reported for larger aneurysms. Similarly, the combined rate of periprocedural mortality and morbidity is not negligible (7.3%) and should be considered when considering the best therapeutic option for these aneurysms.
authors.affiliation: Mayo Medical School, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA.
authors.forename: Waleed
authors.initials: W
authors.lastname: Brinjikji
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lanzino
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Cloft
authors.forename: Alejandro
authors.initials: A
authors.lastname: Rabinstein
authors.forename: David F
authors.initials: DF
authors.lastname: Kallmes
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000473:pathology* / Q000628:therapy*; D007431:Intraoperative Complications / Q000175:diagnosis / Q000473:pathology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000009:adverse effects; D012189:Retrospective Studies; D016896:Treatment Outcome