Outcomes of Microsurgical Treatment for Unruptured Intracranial Aneurysms: A 7-Year Institutional Review

The optimal management of unruptured intracranial aneurysms (UIAs) remains controversial. Options include observation, endovascular treatment, microsurgical intervention, or a combination. However, clear outcome data for UIA treatment remain elusive. This study analyzed UIA treatment outcomes at a quaternary center and explored factors associated with poor neurological outcomes.

All records of patients treated for UIA from 2014 through 2020 were retrospectively reviewed. Inclusion criteria were availability of treatment data, adequate follow-up, and a modified Rankin Scale (mRS) score of ≤2 at admission. Outcomes analyzed included 1-year mRS scores, with a poor neurological outcome defined as an mRS score of >2. Multivariate logistic regression analysis included variables with P < .2 on univariate analysis.

A total of 390 patients met the inclusion criteria (294 [75.4%] women, 96 [24.6%] men). Forty-one (10.5%) had previous aneurysmal subarachnoid hemorrhages (SAHs). The mean (SD) population, hypertension, age, size of aneurysm, earlier SAH from another aneurysm, site of aneurysm (PHASES) score was 4.5 (2.7). Thirty-eight patients (9.7%) had mRS scores >2 at the 1-year follow-up. Of 555 UIAs, 388 (69.9%) were saccular and 77 (13.9%) were in the posterior circulation. Multivariate analysis showed that no tobacco use (odds ratio [OR] 4.35, 95% CI: 1.72-12.5, P = .003), diabetes mellitus (OR 3.09, 95% CI: 1.00-9.29, P = .045), hyperlipidemia (OR 4.33, 95% CI: 1.33-14.0, P = .01), and PHASES score ≥6 (OR 3.92, 95% CI: 1.30-12.7, P = .02) were predictors of poor neurological outcome at the 1-year follow-up. Of the 555 UIAs treated, 1 (0.2%) required retreatment and 12 (2.5%) residual aneurysms were noted on follow-up, with no aneurysmal SAH post-treatment.

Microsurgical treatment of UIAs is associated with low rates of residual aneurysms, retreatment, and poor neurological outcomes. Risk factors for a poor neurological outcome included no history of tobacco use, presence of diabetes mellitus, hyperlipidemia, and a high PHASES score. These findings refute the potential value of treating patients with low PHASES scores.