Surgery for Unruptured Intracranial Aneurysms in the ISAT and ISUIA Era

Background: The ISAT and ISUIA studies, along with the improvement of endovascular treatment (EVT) have strongly influenced the management of intracranial aneurysms (IAs). We present our experience in the microsurgical treatment of unruptured IAs (UIAs) in this context. Methods: We retrospectively reviewed a consecutive series of non-giant UIAs selected for surgery during a five-year period. Patients and aneurysms characteristics, surgical results and outcome assessed by the Glascow Outcome Scale (GOS) at three month follow-up were studied. Results: Eighty-five patients underwent 93 surgical procedures to obliterate 113 UIAs. Those were incidental in 89% of the cases and mainly located on the middle cerebral artery (65%). Patients were assigned to surgery according to their medical history (young, previous subarachnoid haemorrhage), aneurysm characteristics (wide neck, branch at the neck, "small" size, associated "surgical" aneurysm) or failure of EVT (5%). Operatively, 48% of UIAs had thin wall or blebs and 71% were occluded with one titanium clip. Thrombectomy or temporary clipping were necessary in 4% and 11% of the cases, three aneurysms peroperatively ruptured, four were deemed unclippable, three paraclinoid UIAs had an intracavernous residue and 16% were wrapped because of a small neck remnant (class 2). The mortality rate was 0% and 4% of the patients experienced a definitive major neurological deterioration. Final GOS was unchanged in 96% of the patients. Conclusions: Despite reduction in operative cases and in appropriately selected patients ineligible to EVT, microsurgical clipping of non-giant anterior circulation UIAs can still achieve good outcome with very low mortality and neurological morbidity.