Background and Purpose—Smoking and hypertension are important risk factors for atherosclerotic carotid artery disease, but also for intracranial aneurysms. We studied the presence of aneurysms in a series of patients with internal carotid artery (ICA) stenosis and performed a systematic review of the literature to assess in patients with ICA stenosis the prevalence of intracranial aneurysms, gender differences in prevalence, and the size of the aneurysms found.

Methods—In a prospectively collected series of patients with symptomatic ICA stenosis >50% on CTA we assessed the proportion with intracranial aneurysms. We performed "Embase" and "Pubmed" searches for studies on patients with ICA stenosis (domain) and intracranial aneurysms (outcome measurement). We calculated overall prevalence and relative risks for gender, both with corresponding 95% confidence intervals (CI).

Results—We found an intracranial aneurysm in 8 of our 194 patients (4.1%; [95% CI 1.3 to 6.9]). The literature search resulted in 5 relevant and valid articles, totaling 4251 patients. The overall prevalence in all series combined was 3.2% (95% CI 2.7 to 3.7); the prevalence of aneurysms larger than 5 mm was 0.9% (95% CI 0.6 to 1.1). Women had a higher risk then men (relative risk 1.6; [59% CI 1.1 to 2.3]).

Conclusion—About 1% of patients with a symptomatic ICA stenosis have an intracranial aneurysm with a higher than negligible risk of rupture, but in deciding aneurysms treatment the risk of cardiovascular diseases other than aneurismal rupture should be taken into account. The proportion of patients with aneurysms seems higher in series of patients with ICA stenosis than in the general population.