title: Subarachnoid hemorrhage caused by previously diagnosed, previously unruptured intracranial aneurysms: a retrospective analysis of 25 cases.
abstract: OBJECTIVE
  We conducted a retrospective analysis of the clinical features of angiographically diagnosed unruptured intracranial aneurysms that were treated conservatively and subsequently ruptured.
  
  
  METHODS
  At our center, we reviewed the angiographic and clinical features of 25 patients with subarachnoid hemorrhage caused by previously unruptured aneurysms.
  
  
  RESULTS
  Eleven of the 25 patients died, including 1 patient who had undergone surgery. Ten patients had single aneurysms, and 15 had multiple aneurysms. Thus, multiple aneurysms were significantly more common than single aneurysms. The associated disease was cerebral infarction in 12 patients, previous subarachnoid hemorrhage from different aneurysm in 8 patients, intracerebral hemorrhage in 3 patients, and other conditions in 2 patients. Aneurysm size was able to be evaluated after rupture in 20 patients. At initial diagnosis, 16 aneurysms measured less than 5 mm in maximum diameter; the size of most aneurysms had increased by the time of rupture, although the aneurysm size remained less than 5 mm in five patients. No relationship was found between aneurysm rupture and patient age, aneurysm size at initial diagnosis, or time interval from diagnosis to rupture. The incidence of aneurysm rupture in patients with cerebrovascular disease, although higher than the incidence in patients with other underlying disease, was not significant.
  
  
  CONCLUSIONS
  We conclude that small unruptured intracranial aneurysms measuring less than 5 mm are susceptible to the risk of rupture, so that radical treatment or careful follow-up examination should be considered.
authors.affiliation: Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-Akita, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yasui
authors.forename: S
authors.initials: S
authors.lastname: Magarisawa
authors.forename: A
authors.initials: A
authors.lastname: Suzuki
authors.forename: H
authors.initials: H
authors.lastname: Nishimura
authors.forename: T
authors.initials: T
authors.lastname: Okudera
authors.forename: T
authors.initials: T
authors.lastname: Abe
mesh_terms: D000328:Adult; D000368:Aged; D017542:Aneurysm, Ruptured / Q000453:epidemiology; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D015994:Incidence; D002532:Intracranial Aneurysm / Q000150:complications*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000209:etiology*; D013997:Time Factors