title: Natural history of small unruptured anterior circulation aneurysms: a prospective cohort study.
abstract: OBJECTIVE
  The natural history of small unruptured intracranial aneurysms of the anterior circulation in the European population is unclear. Therefore, the management of unruptured intracranial aneurysms <7 mm in the anterior circulation is controversial.
  
  
  METHODS
  Between June 1999 and June 2012, 384 unruptured intracranial aneurysms of the anterior circulation <7 mm in diameter underwent conservative treatment and regular annual follow-up in our institution. Patient- and aneurysm-specific information, as well as information on aneurysm enlargement and rupture, was entered into a prospectively conducted database.
  
  
  RESULTS
  The mean follow-up duration was 48.5±37 months. Three aneurysms enlarged during the follow-up period and were treated by surgical clipping. Three aneurysms were ruptured during the follow-up period. The overall annual incidence of subarachnoid hemorrhage was 0.2% during the follow-up. In the multivariate Cox proportional hazard regression analysis, hypertension (P<0.001; hazard ratio, 2.6; 95% confidence interval, 2.1-3.3) and <50 years of age (P=0.04; hazard ratio, 1.3; 95% confidence interval, 1.01-1.7) were significant independent predictors of aneurysm rupture.
  
  
  CONCLUSIONS
  The present data indicate that the annual incidence of subarachnoid hemorrhage associated with small anterior circulation unruptured intracranial aneurysms is low in this single-institution prospective cohort study. The natural course varies according to arterial hypertension and patient age.
authors.affiliation: From the Departments of Neurosurgery (E.G., H.V., P.S., J.P., J.K., V.S.) and Neuroradiology (R.D.M.d.R., J.B.), Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
authors.forename: Erdem
authors.initials: E
authors.lastname: Güresir
authors.forename: Hartmut
authors.initials: H
authors.lastname: Vatter
authors.forename: Patrick
authors.initials: P
authors.lastname: Schuss
authors.forename: Johannes
authors.initials: J
authors.lastname: Platz
authors.forename: Jürgen
authors.initials: J
authors.lastname: Konczalla
authors.forename: Richard Du Mesnil
authors.initials: Rdu M
authors.lastname: de Rochement
authors.forename: Joachim
authors.initials: J
authors.lastname: Berkefeld
authors.forename: Volker
authors.initials: V
authors.lastname: Seifert
mesh_terms: D000368:Aged; D017542:Aneurysm, Ruptured / Q000175:diagnosis / Q000453:epidemiology; D002560:Cerebrovascular Circulation; D016208:Databases, Factual; D005060:Europe / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis / Q000453:epidemiology; D013525:Surgical Instruments / Q000009:adverse effects; D013997:Time Factors; D016896:Treatment Outcome
keywords: aneurysm; subarachnoid hemorrhage