Outcome after treatment of unruptured intracranial aneurysms in a population-based cohort: a retrospective register study.

Abstract

Population-studies indicate that the incidence of aneurysmal subarachnoid hemorrhage (aSAH) is declining, and that the prevalence of unruptured intracranial aneurysms (uIA) is higher than previously assumed. This suggests the risk of aSAH from an uIA is lower than previously estimated. We therefore aimed to report institution- and population-specific outcomes after treatment of uIAs, and to describe time trends in treatment rates and modalities. This is a registry-based retrospective population-based observational cohort study from the University Hospital of North-Norway (UNN), which provides the only neurosurgical service in northern Norway (population 486,450). We retrieved data for the years 2007 through 2019 from UNN's clinical quality register. The main outcome was change in the modified Rankin Scale score (ΔmRS) after 12 months. Mortality and complication rates were secondary outcomes. We analyzed time trends with Poisson regression. 281 cases underwent treatment, 106/281 (38%) with endovascular and 175/281 (62%) with microsurgical techniques. The mean annual number of cases was 22. We found no significant time trends in the number of cases or treatment modality. 24/281 (9%) had an unfavorable outcome at 12 months, defined as >1 points worsening of the mRS score from baseline. The overall complication rate was 23% and the in-hospital mortality <1%. In this population-based cohort treated for uIA, the outcomes were comparable to those reported in previous reviews.