title: A retrospective analysis on the natural history of incidental small paraclinoid unruptured aneurysm.
abstract: OBJECTIVE
  The optimal consensus concerning treatment of incidental small paraclinoid unruptured intracranial aneurysms (UIAs) remains controversial. The aim of this retrospective study was to reveal the natural history of small paraclinoid UIAs with the goal of informing the treatment plan.
  
  
  METHODS
  524 patients harbouring 568 paraclinoid UIAs (≤5 mm) were retrospectively evaluated during the mean follow-up of 35.4 months. The aneurysms were divided into two groups with respect to arterial branch: related (ophthalmic and superior hypophyseal artery), and non-related. Medical records were reviewed concerning multiple variables, such as sex, age, hypertension (HTN), diabetes mellitus, smoking and aneurysmal factors (size, arterial relationship, multiplicity and the occurrence of rupture and growth). The cumulative risk and the risk factors of aneurysmal rupture and growth were analysed.
  
  
  RESULTS
  Two aneurysmal (0.35%) ruptures and 17 growths (3.0%) were observed during the follow-up of 1675.5 aneurysm-years with an annual rupture of 0.12% and an annual growth of 1.01%. The cumulative survival without aneurysmal growth reached a significant difference in aneurysms ≥4 mm (p=0.001), HTN (p=0.002), and arterial branch-related location (p=0.001). Multivariate analysis disclosed that aneurysm ≥4 mm (HR, 4.41; p=0.003), HTN (HR, 5.74; p=0.003), arterial branch-related location (HR, 6.04; p=0.002), and multiplicity (HR, 0.27; p=0.042) were significant predictive factors for aneurysm growth.
  
  
  CONCLUSIONS
  Although incidental small paraclinoid UIAs have a relatively lower rupture and growth risk, patients with high-risk factors, including aneurysm ≥4 mm, HTN, arterial branch-related aneurysms, and multiple aneurysms must be monitored closely. The limitation of the retrospective nature of this study should be taken into consideration.
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, , Seoul, Korea.
authors.forename: Jin Sue
authors.initials: JS
authors.lastname: Jeon
authors.forename: Jun Hyong
authors.initials: JH
authors.lastname: Ahn
authors.forename: Won
authors.initials: W
authors.lastname: Huh
authors.forename: Young-Je
authors.initials: YJ
authors.lastname: Son
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Bang
authors.forename: Hyun-Seung
authors.initials: HS
authors.lastname: Kang
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Sohn
authors.forename: Chang Wan
authors.initials: CW
authors.lastname: Oh
authors.forename: O-Ki
authors.initials: OK
authors.lastname: Kwon
authors.forename: Jeong Eun
authors.initials: JE
authors.lastname: Kim
mesh_terms: D017542:Aneurysm, Ruptured / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D018450:Disease Progression; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000473:pathology / Q000628:therapy*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Cerebrovascular Disease; Stroke; Vascular Surgery