Vertebral artery hypoplasia as an independent risk factor of posterior circulation atherosclerosis and ischemic stroke

Abstract

Vertebral artery hypoplasia (VAH) is a frequent anatomical variation of vertebral arteries, with emerging evidence suggesting that it contributes to posterior circulation ischemia. However, the relationship between VAH and ischemic stroke remains unknown. Hence, this study aimed to determine the prevalence of VAH in patients diagnosed with acute ischemic stroke who were followed up in a neurology clinic and to determine if it can potentially be a risk factor for atherosclerotic stenosis in vertebrobasilar circulation. This retrospective study included 609 patients diagnosed with acute ischemic stroke between January 1, 2019 and January 1, 2020. Demographic of patients, risk factors, radiological and clinical characteristics were evaluated. Posterior circulation was very common in patients with VAH, and the most common locations of atherosclerotic stenosis were V1 and V4 segments of the vertebral artery and the middle segment of basilar artery. Analysis of the risk factors for atherosclerotic stenosis in patients with posterior circulation acute ischemic stroke suggested that VAH was an independent risk factor. Findings of the study suggest that VAH pre-disposes atherosclerotic stenosis in vertebrobasilar circulation, although its mechanism remains unknown. Hemodynamic parameters associated with atherosclerosis could not be measured in vivo. Thus, to better understand the underlying mechanism, conducting studies that examine blood flow parameters with high-resolution magnetic resonance angiography in patients diagnosed with acute cerebral ischemia patients with VAH is warranted.

Clinical Characteristics of Patients with Vertebral Artery Hypoplasia

“…The results of studies published so far suggest a possible relationship between VAH and increased risk of ischemic stroke or transient ischemic attack (TIA) in posterior vascular area of the brain [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. An existence of a similar relationship was also suggested in the case of significant asymmetry of the VAs (diameter ratio higher than 1:1.7) [ 4 , 6 , 7 , 9 , 19 ].…”

Association of Left Vertebral Artery Hypoplasia with Posterior Circulation Stroke and the Functional Outcome of Patients with Atrial Fibrillation–Related Cardioembolic Stroke

“…It is associated with posterior circulation ischemic stroke due to stenosis in the hypoplastic segment and the resultant ipsilateral cerebellar hypoperfusion. [2][3][4][5] It is uncertain whether VAH influences cardioembolic stroke in the posterior circulation.…”

“…1,2 Previous studies reported that VAH is associated with ipsilateral atherosclerotic stenosis in the VA and posterior circulation stroke. 3,5 Thierfelder et al 4 reported that VAH could lead to relative hypoperfusion in the ipsilateral PICA. Bilateral VAH may have a unique pattern in the infarction territory that involves multiple vascular territories, and it is mostly bilateral.…”

“…It is associated with posterior circulation ischemic stroke due to stenosis in the hypoplastic segment and the resultant ipsilateral cerebellar hypoperfusion. [2][3][4][5] It is uncertain whether VAH influences cardioembolic stroke in the posterior circulation.Although conflicting results exist, previous studies have reported that cardiogenic cerebral embolisms have a right-sided propensity in acute stroke. 6,7 This is because the innominate artery, which supplies the right VA and right common carotid artery, has the largest caliber and travels superior and parallel to the direction of the ascending aorta.…”

Vertebral Artery Stenosis: A Narrative Review

“…Similar to several other conditions, the first line of treatment for the disease of the vertebral artery is the modification of risk factors, including physical activity, maintaining a healthy diet, and smoking cessation [12]. Cigarette smoking has been indicated as a risk factor in various causes of vertebral artery stenosis, such as vertebral artery hypoplasia, V1 diseases, and vertebral artery dissections; therefore, smoking cessation may help reduce the incidence of vertebral artery stenosis [9,10,49]…”