Differences in internal carotid artery tortuosity in ruptured and unruptured anterior circulation aneurysms. A matched case-control study

Abstract

Objective: Tortuosity of the internal carotid artery is believed to contribute to the formation of intracranial aneurysms, although there is scant literature on its role as a risk factor for rupture specifically. Therefore, this study investigated the influence of cervical internal carotid artery (cICA) tortuosity on rupture of aneurysms of the anterior cerebral circulation.

Methods: Angiographic imaging studies from patients who underwent endovascular embolisation for anterior circulation aneurysms at a tertiary centre were identified. 83 patients with a history of aneurysmal rupture and subarachnoid haemorrhage (SAH group) were matched for age, aneurysm location and size, history of subarachnoid haemorrhage and hypertension to 83 subjects with unruptured aneurysms (control group). cICA tortuosity was assessed utilising subjective (kinks, loops or coils) and objective (tortuosity index) parameters.

Results: Subjective cICA tortuosity was identified in 33.7% and 56.6% of patients in the SAH and control groups respectively (OR 0.39 [95% CI 0.21-0.75]). Objective cICA tortuosity was present in 35.7% and 46.8% of SAH and control patients (OR 0.63 [95% CI 0.32-1.27]). OR values are suggestive of cICA tortuosity as a negative predictor of aneurysmal rupture, with more predictive power attributed to the subjective assessment, despite the limited statistical significance of the objective results.

Conclusions: This study demonstrated an increased presence of cICA tortuosity in unruptured aneurysms compared to ruptured aneurysms, suggesting it is unlikely to represent a risk factor for rupture. Further research in the form of longitudinal observational studies of untreated aneurysms would aid in investigating cICA tortuosity as a protective factor.

Keywords: Arterial tortuosity; Internal carotid artery (ICA); Intracranial aneurysm; Neurointervention; Subarachnoid haemorrhage.