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Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

Published on: August 11, 2015

Outcome After Treatment of Unruptured Intracranial Aneurysms in a Population-Based Cohort: A Retrospective Register

Mathilde Vea Iversen¹, Tor Ingebrigtsen², Roar Kloster²

¹Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway.

World Neurosurgery

|June 23, 2026

Abstract

Background:

Population-studies indicate that the incidence of aneurysmal subarachnoid hemorrhage is declining, and that the prevalence of unruptured intracranial aneurysms (uIAs) is higher than previously assumed. This suggests the risk of aneurysmal subarachnoid hemorrhage 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.

Methods:

This is a registry-based retrospective population-based observational cohort study from the University Hospital of North-Norway, which provides the only neurosurgical service in northern Norway (population 486,450). We retrieved data for the years 2007 through 2019 from University Hospital of North-Norway's clinical quality register. The main outcome was change in the modified Rankin Scale score after 12 months. Mortality and complication rates were secondary outcomes. We analyzed time trends with Poisson regression.

Results:

A total of 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. Twenty-four of 281 (9%) had an unfavorable outcome at 12 months, defined as >1 points worsening of the modified Rankin Scale score from baseline. The overall complication rate was 23% and the in-hospital mortality <1%.

Conclusions:

In this population-based cohort treated for uIA, the outcomes were comparable to those reported in previous reviews.

Keywords:

Clinical quality register Outcome research Population-based Subarachnoid haemorrhage Treatment Unruptured intracranial aneurysms

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