• Erdem Güresir, Hartmut Vatter, Patrick Schuss, Johannes Platz, Jürgen Konczalla, Richard Du Mesnil de Rochement, Joachim Berkefeld, and Volker Seifert.
• 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.
• Stroke. 2013 Nov 1;44(11):3027-31.

Background And PurposeThe 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.MethodsBetween 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.ResultsThe 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.ConclusionsThe 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.

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