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Might vertebral artery hypoplasia truly be a benign anomaly?

Year: 2026
Type: article
Abstract: Introduction: The vertebral arteries are muscular arteries, branches of the subclavian artery, 15–20 cm in length and 3.0–5.0 mm in diameter. Hypoplasia of one vertebral artery can be seen in 1.4–26.5% of the healthy population. It may be bilateral or unilateral. There are different definitions of vertebral artery hypoplasia: a vertebral artery diameter of less than 2.0 mm, a diameter of less than 3.0 mm, a ratio of more than 1:1.7 between the two sides, a peak systolic velocity below 40 cm/s on Doppler ultrasonography, and a resistance index above 0.75. Although vertebral artery hypoplasia is mostly asymptomatic, it has been reported to cause posterior circulation infarcts, vertebral artery stenosis, or dissection. It can be found in patients presenting with dizziness, weakness, and headache. It is not clear whether a vertebral artery ending in the posterior inferior cerebellar artery (PICA) is clinically symptomatic or whether it leads to posterior circulation infarction. In this study, we retrospectively investigated whether patients with medullary infarction had vertebral artery hypoplasia in comparison with patients who had anterior circulation infarcts. We tried to determine whether vertebral artery hypoplasia and atresia constitute risk factors for medullary infarction regarding etiologic stroke subtypes.Methods: The study included 45 patients with acute medullary infarction on diffusion-weighted imaging (DWI) who presented to our clinic and 45 control patients with acute infarcts in the territory of the internal carotid artery and its branches. The demographic data, computed tomography angiography (CTA) or magnetic resonance angiography (MRA) findings, and etiologic stroke subtype according to the “Causative Classification System for Ischemic Stroke” were retrospectively determined for all patients. Vertebral artery hypoplasia was defined as a vertebral artery diameter below 2 mm in at least two consecutive segments between V1 and V4 on MRA or CTA, which could not be attributed to an acquired vascular disease such as atherosclerosis, dissection, vasospasm, or vasculitis. The groups were compared using the chi-square test, Fisher’s exact test, and the t-test; p<0.05 was considered significant.Results: The mean age of the 45 patients with medullary infarction was 58.11±13.59 (range: 29–77); 33 were men (73.33%) and 12 were women (26.67%). In the control group of patients with anterior circulation infarcts, the mean age was 67.04±14.0 (range: 27–91), with 27 men (60%) and 18 women (40%). There was no significant difference between the two groups. In 10 patients (22.22%), the medullary infarct was accompanied by infarcts in other brainstem regions, the occipital lobe, or the cerebellum; 35 (77.78%) had isolated medullary infarcts. The etiologic ischemic stroke subtype was large artery atherosclerosis in 23 patients (51.11%), cardioembolism in 2 (4.44%), lacunar in 4 (8.89%), dissection in 9 (20%), other rare causes in 2 (4.44%), and cryptogenic in 5 (11.11%). Structural asymmetry of the vertebral artery was present in 10 patients (22.22%) in the control group and 13 patients (28.89%) in the study group. Of the 13 patients with medullary infarction and vertebral artery hypoplasia, in 6 (13.33%) the vertebral artery ended in the PICA and the V4 segment was completely atretic, and in 9 the hypoplasia-atresia was in the right vertebral artery. (69.23%). In four patients, the infarct was outside the territory of the hypoplastic vertebral artery. In conclusion, 9 patients (20%) had a medullary infarct that could be attributed to a hypoplastic-aplastic vertebral artery (Figure 1). In three patients (6.67%), the medullary infarct was attributed to superimposed atherosclerotic occlusion of a hypoplastic vertebral artery (Figure 2). In the remaining 6 patients (13.33%), no clear cause other than hypoplasia could be established, although one was thought to be a lacunar infarct and one to be related to COVID-19 vaccination (13.33%); the age range of these patients was 43–77. Dissection was not the cause of stroke in any patient with a hypoplastic vertebral artery. No intracranial vertebral artery vasospasm causing medullary infarction was observed (Figure 1 and 2).Discussion/Conclusion: The side and sex predisposition of vertebral artery hypoplasia vary among ethnic populations. In an analysis of 80 patients, a vertebral artery ending in the PICA was found 3 times more often in patients with posterior circulation infarcts than in the healthy population. In our study, the frequency of vertebral artery hypoplasia or atresia was not different between patients with medullary infarcts and those with anterior circulation infarcts. Vertebral artery hypoplasia has not been defined as a stroke risk factor on its own. It may contribute to stroke when additional atherosclerotic risk factors are present. To distinguish acquired occlusion or narrowing of the vertebral artery from congenital hypoplasia or atresia, the following may be valuable: a hypo-/isodense thrombus along the vessel course on angiographic images, a double lumen, the crescent sign, the “pig tail” sign, alternating narrowing and dilatation, retrograde filling of the distal segment, the location of the occlusion (atherothrombotic if at the ostium, dissection if at the V3-V4 junction), normalization of an occluded or stenotic lumen on follow-up imaging, accompanying findings of atherosclerosis such as calcification, plaque, and stenosis along the course of the symptomatic vessel or in other extra-intracranial vessels, and findings of atherosclerotic chronic small vessel disease in the white matter on FLAIR series. Clinically, atherosclerosis, dissection, or congenital hypoplasia can also be distinguished by the presence of headache, minor neck trauma, and accompanying atherosclerotic risk factors.Keywords:
DOI: 10.66789/tjcvd.2026.888
Language: English
Field: Medicine
Open Access status: diamond
OpenAlex ID: W7225819363
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