One-Year Morbidity and Mortality Rates Associated with Clipping Unruptured Intracranial Aneurysms

Objective: To assess the morbidity and mortality rates associated with surgical ligation of unruptured intracranial aneurysms (UIA) over a 6-year period at a single institution.

Methods: A retrospective review of all patients operated on by three different neurosurgeons who underwent an orbitozygomatic (oz) or modified oz to have their UIA clipped from May 2012 to January 2018 at a tertiary academic hospital was performed.

Results: Of the 41 clipped UIA patients, 31 (73%) were female and the average age was 53 (SD: 13). On average, the cohort’s aneurysm dome was 6.9 mm (SD: 3.6 mm) with a neck width of 4.5 mm (SD: 2.0 mm). Nearly half (n = 21) of the cohort presented with multiple aneurysms, for a total of 49 clipped UIAs. The most common UIA locations were the middle cerebral artery (n = 31; 43%), anterior communicating artery (n = 5; 10%), internal carotid artery (n = 5; 10%), posterior communicating artery (n = 5; 10%), and anterior choroidal artery (n = 3; 6%). Surgical duration from 33 patients showed an average of 280 minutes (SD: 96), and the average length of stay from surgery to discharge was 7.5 days (SD: 5). The collective 30-day and 1-year mortality rates were both 0 for 35/41 patients (6 patients lost to follow-up). The collective 30-day and 1-year morbidity rates were 17.1% (6/35) and 8.6% (3/35), respectively. There was a 4.8% (2/41) intraoperative stroke rate, both of which had improved by 1-year follow-up. Postoperative complications included stroke in six patients (all of which had complete to near-complete recovery at 1-year follow-up), seizures in three patients (all of which were seizure free at 1-year follow-up), CSF leakage in one patient (subsequently repaired surgically), epidural hematoma in one patient (subsequently evacuated), orbital swelling in one patient (resolved by 1-year follow-up), unilateral hemiparesis in one patient (present at 1-year follow-up), and persistent long-term memory deficits in one patient (present at 1-year follow-up).

Conclusion: Depending on the size, UIAs have up to a 50% 5-year rupture risk, with ruptured aneurysms associated with a 69% mortality rate. Surgical clipping of UIAs is reported to have a 2.6 and 10.9% mortality and morbidity rate, respectively. Our single institutional retrospective review demonstrated a 0 and 8.6% 1-year mortality and morbidity rate, respectively. As such, surgical clipping is warranted to mitigate the potentially devastating consequences of aneurysm rupture. Nonetheless, surgical intervention carries numerous risks which should be discussed with the patient prior to surgery.