title: Unruptured cerebral aneurysms do not shrink when they rupture: multicenter collaborative aneurysm study group.
abstract: BACKGROUND
  The International Study of Intracranial Aneurysms found that for patients with no previous history of subarachnoid hemorrhage, small (< 7 mm) anterior circulation and posterior circulation aneurysms had a 0% and 2.5% risk of subarachnoid hemorrhage over 5 years, respectively.
  
  
  OBJECTIVE
  To determine whether cerebral aneurysms shrink with rupture.
  
  
  METHODS
  The clinical databases of 7 sites were screened for patients with imaging of cerebral aneurysms before and after rupture. Inclusion criteria included documented subarachnoid hemorrhage by imaging or lumbar puncture and intracranial imaging before and after cerebral aneurysm rupture. The patients were evaluated for aneurysm maximal height, maximal width, neck diameter, and other measurement parameters. Only a change of ≥ 2 mm was considered a true change.
  
  
  RESULTS
  Data on 13 patients who met inclusion criteria were collected. The median age was 60, and 11 of the 13 patients (84.6%) were female. Only 5 patients had posterior circulation aneurysms. None of the aneurysms had a significant decrease in size. One aneurysm decreased by 1.8 mm in maximum size after rupture (7.7%). Six aneurysms had an increase in maximum size of at least 2 mm after rupture (46.2%) with a mean increase of 3.5 mm (± 0.5 mm).
  
  
  CONCLUSIONS
  Unruptured aneurysms do not shrink when they rupture. The large percentage of ruptured small aneurysms in previous studies were likely small before they ruptured.
authors.affiliation: Department of Neurosurgery, University of Florida, Gainesville, Florida 32610, USA. maryam.rahman@neurosurgery.ufl.edu
authors.forename: Maryam
authors.initials: M
authors.lastname: Rahman
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ogilvy
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Zipfel
authors.forename: Colin P
authors.initials: CP
authors.lastname: Derdeyn
authors.forename: Adnan H
authors.initials: AH
authors.lastname: Siddiqui
authors.forename: Ketan R
authors.initials: KR
authors.lastname: Bulsara
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Kim
authors.forename: Howard A
authors.initials: HA
authors.lastname: Riina
authors.forename: J
authors.initials: J
authors.lastname: Mocco
authors.forename: Brian L
authors.initials: BL
authors.lastname: Hoh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000473:pathology*; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000473:pathology*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D055815:Young Adult