--- title: Vertebral artery stenosis description: What vertebral artery stenosis (narrowing of the vertebral artery) is, why atherosclerosis of this artery can lead to a transient ischaemic attack and stroke in the back of the brain, how the narrowing is found, which treatment approaches guidelines describe, and when to call an ambulance. type: disease aliases: - narrowing of the vertebral artery - vertebral artery occlusion - occlusion and stenosis of vertebral artery - vertebral artery atherosclerosis - vertebrobasilar ischaemia sources: - tier: guideline org: minzdrav-rf title: Ишемический инсульт и транзиторная ишемическая атака year: 2024 url: https://cr.minzdrav.gov.ru/view-cr/814_1 - tier: reference org: msd-manuals title: Transient Ischemic Attack (TIA) (MSD Manual Professional Version) year: 2026 url: https://www.msdmanuals.com/professional/neurologic-disorders/stroke/transient-ischemic-attack-tia - tier: reference org: msd-manuals title: Ischemic Stroke (MSD Manual Professional Version) year: 2026 url: https://www.msdmanuals.com/professional/neurologic-disorders/stroke/ischemic-stroke - tier: reference org: msd-manuals title: Overview of Stroke (MSD Manual Professional Version) year: 2026 url: https://www.msdmanuals.com/professional/neurologic-disorders/stroke/overview-of-stroke - tier: reference org: msd-manuals title: Overview of Stroke (MSD Manual Consumer Version) year: 2026 url: https://www.msdmanuals.com/home/brain-spinal-cord-and-nerve-disorders/stroke/overview-of-stroke - tier: reference org: msd-manuals title: Ischemic Stroke (MSD Manual Consumer Version) year: 2025 url: https://www.msdmanuals.com/home/brain-spinal-cord-and-nerve-disorders/stroke/ischemic-stroke sources_checked: 2026-10-14 review: null --- Vertebral artery stenosis is a narrowing of a vertebral artery; a complete blockage is called an occlusion. This article is about narrowing caused by atherosclerosis, in which fatty deposits (plaques) build up in the artery wall. The vertebral arteries carry blood along the back of the neck, and inside the skull they join to form the basilar artery. They supply the back of the brain: the brainstem, the cerebellum and the posterior part of the cerebral cortex. The narrowing can cause a transient ischaemic attack (TIA) or a stroke; more about these in the article on [carotid artery stenosis](../carotid-artery-stenosis/).

The arteries are shown from the front, so the right side of the body is on the left. The vertebral artery starts from the subclavian artery. Both vertebral arteries rise through the neck and join inside the skull to form the basilar artery; blood flows up them to the back of the brain.

A plaque has narrowed the start of the left vertebral artery. Emboli that break off plaques in arteries most often come from the first parts of the carotid or vertebral arteries. Less blood gets past the narrowing, and the brain may not get enough of it. A blood clot can form on the plaque; a fragment of it may break off, travel with the blood and block an artery in the brain.

## Why it happens In atherosclerosis, plaques gradually grow and narrow the artery. A blood clot can form on a plaque: it may block the artery, or break off and block an artery in the brain. If the artery narrows slowly, other arteries sometimes widen and take over part of its work, and there may be no symptoms. Risk factors for stroke that can be changed include high blood pressure, diabetes, smoking, drinking too much alcohol, high cholesterol and obesity. More about them in the articles on [hypertension](../hypertension/) and [dyslipidaemia](../dyslipidemia/). This is not the same as subclavian steal syndrome: there the subclavian artery is narrowed before the vertebral artery branches off it, and when the arm is working, blood in the vertebral artery flows backwards; more in the article on [subclavian artery stenosis](../subclavian-artery-stenosis/). The Russian Ministry of Health guideline names the main mechanisms of atherothrombotic stroke as artery-to-artery embolism (by a thrombus or a fragment of atheroma), hypoperfusion or a combination of the two; embolism is most often associated with unstable plaques in the proximal segments of the carotid or vertebral arteries. The vertebral and basilar arteries form the posterior (vertebrobasilar) circulation of the brain; it communicates with the anterior circulation in the circle of Willis via the posterior communicating artery. In ICD-10, the stenosis is coded I65.0, "Occlusion and stenosis of vertebral artery". ## Symptoms When branches of the vertebral arteries are affected, the most common symptoms are dizziness and a spinning sensation (vertigo), double vision or loss of vision in both eyes, and weakness on one or both sides of the body. Slurred speech, confusion and loss of coordination can also occur. A TIA begins suddenly, usually lasts 2 to 30 minutes and then goes away completely. Repeated attacks in the back of the brain may differ somewhat from one another. Vertebrobasilar territory (MSD): unilateral or bilateral cranial nerve deficits (nystagmus, vertigo, dysphagia, dysarthria, diplopia, blindness), truncal or limb ataxia, crossed motor and sensory deficits, impaired consciousness, coma, and death if basilar artery occlusion is complete. With vertebral artery involvement, the Russian Ministry of Health guideline describes the medial medullary syndrome and the lateral medullary syndrome (Wallenberg–Zakharchenko): vertigo, ataxia, Horner syndrome, dysarthria, dysphagia, dysphonia, hiccups and sensory disturbances. Vertigo and nystagmus in a patient with suspected stroke suggest a vertebrobasilar stroke; neck pain may point to dissection. ## How it is diagnosed After a TIA or a stroke, doctors check blood flow in the arteries of the neck and head with ultrasound and/or CT or MR angiography. CT and MR angiography show the arteries of the back of the brain better than carotid ultrasound. After a TIA, tests are done quickly, usually in hospital: the risk of stroke is already high in the first day or two. The Russian Ministry of Health guideline (grade of recommendation A, level of evidence 1) recommends assessing blood flow in the vessels of the neck and head by radiological and/or ultrasound methods in patients with a TIA; CTA and contrast-enhanced MRA detect occlusions and stenoses of the precerebral and cerebral vessels and variants of the circle of Willis. ## How it is treated If the narrowing has already caused a TIA or a stroke, the doctor prescribes treatment that lowers the risk of another stroke. It is also important to deal with risk factors: smoking, high blood pressure and high cholesterol. The doctor decides exactly what to prescribe. The Russian Ministry of Health guideline does not advise open operations on the vertebral artery (removing the plaque, called endarterectomy, or moving the artery to a new site, called transposition) to prevent another stroke, even if symptoms keep coming back despite treatment with medicines: their benefit has not been proven. According to the MSD Manual, widening the artery from the inside through a catheter, sometimes with a stent, is possible in selected people whose artery is narrowed by 50–99% and whose symptoms keep coming back despite optimal treatment with medicines. The Russian Ministry of Health guideline: in ischaemic stroke or TIA due to symptomatic extracranial vertebral artery stenosis, optimal medical therapy is recommended to lower the risk of recurrent stroke (grade of recommendation C, level of evidence 5); endarterectomy and transposition of the vertebral artery for recurrent symptoms despite such therapy are not recommended because of insufficient evidence (grade of recommendation B, level of evidence 2). MSD: extracranial vertebral angioplasty and/or stenting can be used in selected patients with recurrent symptoms of vertebrobasilar ischaemia despite optimal medical treatment and a vertebral artery obstruction of 50–99%. ## When to call an ambulance The danger of stenosis is TIA and stroke, which are emergencies. Call an ambulance straight away on your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) if there is sudden weakness or numbness of one side of the face, an arm or a leg, difficulty speaking, confusion, double vision or loss of vision, or sudden dizziness or loss of balance and coordination, especially with a fall, even if the symptom goes away quickly. Sudden difficulty swallowing can also be a sign that the back of the brain is not getting enough blood. The Russian Ministry of Health guideline describes a quick test to recognise a stroke: ask the person to smile, to speak and to raise both arms. If they suddenly cannot do one of these, call an ambulance straight away, describe the symptoms and tell the paramedics when they began. Do not give the person anything by mouth: stroke is treated only in hospital. According to the Russian Ministry of Health guideline, the simplified scales used by ambulance staff are worse at detecting a stroke in the back of the brain than in the carotid territory, so the other signs above matter too. If the symptoms went away within a few minutes, it may have been a TIA. Still call an ambulance: the risk of stroke is highest in the first day or two.