Impacts of a Size Ratio on Outcome in Patients with Surgically Treated Unruptured Nondissecting Anterior Cerebral Artery Aneurysms.

Abstract

Anterior cerebral artery aneurysms (ACAs) are characterized by higher rupture rate and small size at rupture. It was shown that the aneurysm/vessel size ratio, and not the absolute size, might predict the risk of rupture in small unruptured intracranial aneurysms. The present study aimed to investigate the relationship between a size ratio and outcome in patients with unruptured nondissecting ACA aneurysms (UNDAs). A total of 187 consecutive patients with 12 A1 (6.2%), 149 anterior communicating artery (77%), and 33 distal ACA (17%) aneurysms were retrospectively evaluated. The size ratio was defined as (size of aneurysm)/(size of parent artery). Neurologic worsening (NW) was defined as an increase in score of 1 or more on the modified Rankin Scale (mRS). The mean age of the patient population was 63 ± 11 years and 132 UNDAs (68%) were seen in women. Complete, partial neck clipping, and aneurysm trapping were archived in 188 (97%), 2 (1.0%), and 4 (2.1%) UNDAs, respectively. An excellent outcome (mRS score 0) at 12 months was archived in 177 (93%) UNDAs overall and 177 (95%) in UNDAs with preoperative mRS score of 0 (n = 186). Postoperative ischemic lesions (odds ratio, 193; 95% confidence interval, 17-2205; P < 0.0001) and the size ratio >3.0 (odds ratio, 11; 95% confidence interval, 1.2-105; P = 0.031) were related to 12-month NW on multivariate analysis. The aneurysm size was not related to 12-month NW. The present study showed that the size ratio, and not the absolute size, was related to 12-month NW in surgically treated UNDAs.