title: Small versus Large Ruptured Intracranial Aneurysm: Concerns with the Site of Aneurysm.
abstract: Although size is one of the strongest predictors, small aneurysms often rupture. We compared the characteristics of small and large ruptured intracranial aneurysms (RIAs) according to their location to find the factors associated with small RIAs in each location.
  
  
  
  Patients with subarachnoid hemorrhage due to saccular RIAs were consecutively enrolled. The sizes were dichotomized as small (<5 mm) or large, and the location was classified as paraclinoid-distal internal carotid artery, sidewalls of anterior or middle cerebral artery (MCA; sidewall), MCA-bifurcation, anterior or posterior communicating artery (Acom or Pcom, respectively), and posterior circulation RIAs. Independent factors associated with small RIAs compared to large RIAs were investigated in each location.
  
  
  
  Small RIAs were observed in 384 of 791 patients (48.5%), and were most commonly located at Acom (17.1%) followed by Pcom (9.0%) and sidewalls (7.2%). Female sex (OR 3.038; 95% CI 2.099-4.395), young age (OR 0.971; 95% CI 0.958-0.985), hypertension (OR 1.412; 95% CI 1.033-1.930) and multiple aneurysms (OR 1.942; 95% CI 1.335-2.824) were associated with small RIAs. By location, sidewall aneurysms (OR 2.183; 95% CI 1.049-4.542) were associated with small RIAs, whereas MCA-bifurcation (OR 0.318; 95% CI 0.168-0.599) and Pcom aneurysms (OR 0.511; 95% CI 0.277-0.944) were associated with large RIAs. The presence of multiple aneurysms (OR 4.69; 95% CI 1.45-21.19) was associated with small RIAs at sidewalls, and young age, female sex, hypertension and the presence of bilateral A1 (OR 1.85; 95% CI 1.09-3.13) were associated with small RIAs at Acom. Acom RIAs with bilateral A1 was smaller than those with unilateral A1 (4.7 ± 2.1 vs. 5.8 ± 2.6 mm; p < 0.001).
  
  
  
  Intracranial aneurysms which rupture below 5 mm are not uncommon, and the factors associated with small-sized RIAs differ according to location. Sidewall aneurysms, with multiple aneurysms and Acom aneurysms with bilateral A1 may rupture even at small size.
authors.affiliation: Department of Neurology Kyung Hee University Hospital, Kyung Hee University College of Medicine, Seoul, Korea.
authors.forename: Bum Joon
authors.initials: BJ
authors.lastname: Kim
authors.forename: Hyun Goo
authors.initials: HG
authors.lastname: Kang
authors.forename: Byeong-Duk
authors.initials: BD
authors.lastname: Kwun
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Ahn
authors.forename: Jisung
authors.initials: J
authors.lastname: Lee
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Dong-Wha
authors.initials: DW
authors.lastname: Kang
authors.forename: Jong S
authors.initials: JS
authors.lastname: Kim
authors.forename: Sun U
authors.initials: SU
authors.lastname: Kwon
mesh_terms: D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging / Q000209:etiology*; D002533:Cerebral Angiography / Q000379:methods; D000072226:Computed Tomography Angiography; D016208:Databases, Factual; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000209:etiology*; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging / Q000209:etiology*