Subarachnoid Hemorrhage from Ruptured Internal Carotid Artery Aneurysm: Association with Arterial Tortuosity

Many researchers have found a correlation between tortuous arteries and development of aneurysms in cerebral arteries. We decided to determine whether tortuosity of the internal carotid artery can be related to its aneurysm rupture. We retrospectively analyzed the internal carotid artery anatomy of 149 patients with internal carotid artery aneurysms. For each patient, we calculated relative length (RL), sum of angle metrics (SOAM), triangular index (TI), product of angle distance (PAD), and inflection count metrics (ICM). A total of 33 patients (22.15%) had subarachnoid hemorrhage. These patients had significantly lower SOAM (0.31 ± 0.17 vs. 0.42 ± 0.21; P < 0.01), TI (0.27 ± 0.09 vs. 0.31 ± 0.11; P = 0.03) and ICM (0.25 ± 0.11 vs. 0.31 ± 0.17; P = 0.04). In multivariate logistic regression analysis, higher SOAM (odds ratio, 0.780; 95% confidence interval, 0.619–0.961; P = 0.025) remained independently associated with lower risk of internal carotid artery aneurysm rupture. In addition, we found significant positive correlation of aneurysm dome size with SOAM (R = 0.224; P = 0.013) and PAD (0.269; P < 0.01). Our study also showed that age (R = 0.252; P = 0.036), Glasgow Coma Scale score (R = –0.706; P < 0.01), and TI (R = –0.249; P = 0.042) were independently correlated with modified Rankin Scale score on discharge. Lower tortuosity might be a protective factor against internal carotid artery aneurysm rupture and poor outcome after subarachnoid hemorrhage. Higher tortuosity is correlated with internal carotid artery aneurysm growth.