A retrospective registry analysis found no correlation in stroke patients who had primarily small, saccular aneurysms.
There appears to be no association between the presence of unruptured intracranial aneurysms and the risk of stroke, according to a recent retrospective analysis of registry participants.
“Despite recent advances in stroke care, one-third of ischemic strokes remain classified as cryptogenic,” write the authors, led by Monica Lin Chen, BA (Weill Cornell Medicine, New York, NY), in a paper published online recently in Stroke.
“It has been suggested that unruptured intracranial aneurysms may form a nidus for thrombus formation and downstream embolization resulting in brain infarction,” they note. “Because unruptured aneurysms affect ~3% of the adult population and are often found incidentally during evaluation for ischemic cerebrovascular events, they may represent an underappreciated source of strokes that are currently cryptogenic.”
The investigators conducted a within-subjects case-control study of 1,541 acute ischemic stroke patients prospectively enrolled in the Cornell Acute Stroke Academic Registry (CAESAR) from 2011 to 2016. All had received an MRI of the brain and arterial imaging of the head within 14 days of admission. Reviewers blinded to the study hypothesis ascertained aneurysms from the neuroradiologist’s clinical report of the arterial imaging findings. Aneurysms of the anterior communicating artery or in the posterior circulation were not counted in the analysis.
In all, 11.4% of the registry patients had an intracranial aneurysm. There was no difference in the prevalence of aneurysms occurring on the side ipsilateral versus contralateral to the infarction, with a risk ratio (RR) of 1.2 (95% CI 0.9-1.5).
In a secondary analysis of the 1,244 patients with stroke in a single anterior circulation territory, there was no significant association between aneurysms and ipsilateral stroke (RR 1.2; 95% CI 0.8-1.9). Similarly, there was no association found between aneurysms and ipsilateral strokes in the 619 patients with cryptogenic stroke (RR 1.4; 95% CI 0.9-2.0) or in the 485 patients with cryptogenic stroke in a single anterior circulation territory (RR 1.7; 95% CI 0.8-3.3).
Additionally, the results did not change when the investigators counted only those aneurysms that were > 3 mm in diameter or > 5 mm in diameter.
Literature Limited on Possible Correlation
“Our findings suggest that unruptured aneurysms are unlikely to be a significant cause of stroke at a population level,” write the authors. “However, our results do not rule out that specific aneurysms can in rare cases result in thromboembolic stroke. The risk of thromboembolism from an aneurysm likely depends on various lesion characteristics such as size and location.”
Commenting on the study for Neurovascular Exchange, Kimon Bekelis, MD, (Dartmouth-Hitchcock Medical Center, Lebanon, NH), indicated that it is important due to the “limited literature on the correlation of stroke and unruptured cerebral aneurysms.”
Since no link between the presence of aneurysms and stroke risk was observed, the study does not suggest any need for a change in clinical management, he added. He noted some limitations, however.
“This is a retrospective analysis, and therefore it suffers from selection bias. The results cannot be generalized to aneurysms less of 5 mm,” Bekelis said. “Additionally, posterior circulation aneurysms, anterior cerebral, or anterior communicating aneurysms were excluded.”
Chen ML, Gupta A, Chatterjee, A et al. Association between unruptured intracranial aneurysms and downstream stroke. Stroke 2018;Epub ahead of print.
Chen and Bekelis report no relevant conflicts of interest.