title: Risks of surgery for patients with unruptured intracranial aneurysms.
abstract: BACKGROUND
  With the widespread use of less invasive imaging tools, such as magnetic resonance angiography and computed tomographic angiography, unruptured cerebral aneurysms are found much more often than in the past. This retrospective study was undertaken to determine the risk factors for surgical intervention in a patient with an unruptured intracranial aneurysm.
  
  
  METHODS
  Over a 5-year period, 1,558 patients with intracranial aneurysms underwent surgery at our center. Of these, 310 patients (20%) with unruptured aneurysms were included in this study.
  
  
  RESULTS
  Out of 310 patients with unruptured aneurysms, 292 (95%) had a favorable outcome, and only one patient (0.3%) with a giant vertebral artery aneurysm died. Aneurysm size larger than 15 mm and location of the aneurysm in the posterior circulation were independent risk factors associated with less favorable outcomes. Patients with a single aneurysm had a better outcome than did patients with multiple aneurysms.
  
  
  CONCLUSIONS
  Our results support the contention that surgical treatment of unruptured intracranial aneurysms carries a low risk of morbidity and mortality and may improve the outcome in patients harboring cerebral aneurysms by preventing the devastating effects of subarachnoid hemorrhage. Aneurysm size, location, and number were risk predictors for surgical morbidity in patients with unruptured aneurysms.
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Y I
authors.initials: YI
authors.lastname: Orz
authors.forename: K
authors.initials: K
authors.lastname: Hongo
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: H
authors.initials: H
authors.lastname: Nagashima
authors.forename: M
authors.initials: M
authors.lastname: Osawa
authors.forename: K
authors.initials: K
authors.lastname: Kyoshima
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
mesh_terms: D000367:Age Factors; D000368:Aged; D017558:Elective Surgical Procedures; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012422:Rupture, Spontaneous; D016896:Treatment Outcome