The article describes a case of congenital hypoplasia of the left vertebral artery in a 57-year-old patient in combination with a cerebral infarction caused by vertebrobasilar insufficiency. Concomitant diseases: arterial hypertension, dyslipidemia, impaired fat metabolism (BMI – 33 kg/m2), high-risk coronary heart disease according to the SCORE scale. On the eve of hospitalization, he noted a short-term loss of consciousness when bending forward and impaired coordination of movements. Objective status: muscle strength was preserved in all muscle groups; muscle tone was not changed; sensory disorders were absent; he staggered in the Romberg pose; performed the finger test satisfactorily on both sides; his gait was uncertain. CT scans of the vessels of the neck and brain with angiography revealed a narrowing of the left vertebral artery. Its diameter is almost 1/3 smaller than that of similar sections of the right vertebral artery and varies from 1 mm at the C1 level to 2.5 mm in the V4 segment. A defect in the contrast of the left vertebral artery was found due to prolonged soft atherosclerotic plaque without signs of calcification. The left internal carotid artery has an S-shaped bend in the extracranial region at the C1–C2 level. At the mouth of the right internal carotid artery (at the level of the bifurcation of the right common carotid artery), a parietal calcified atherosclerotic plaque with a narrowing of the lumen to 15 % is detected. An MRI scan of the brain revealed a pattern of infarction of the left hemisphere of the cerebellum.

Conclusion: congenital asymptomatic hypoplasia of the vertebral artery is a risk factor for the development of cerebral circulatory disorders. The progression of systemic atherosclerotic vascular lesions contributes to the development of vertebrobasilar stroke.