A vertebral artery dissection (VAD) is a tear in the inner wall of one of the two vertebral arteries, the blood vessels that run up through the neck and into the back of the brain. When this inner lining tears, blood seeps between the layers of the artery wall, forming a clot that can narrow or block blood flow. This matters because the vertebral arteries supply critical structures in the brainstem and cerebellum, and a dissection can lead to stroke in otherwise young, healthy people.
How the Injury Happens Inside the Artery
Your vertebral arteries have three layers, like most arteries: a smooth inner lining, a muscular middle layer, and a tough outer coat. A dissection starts when the inner lining develops a tear. Blood under arterial pressure forces its way into the space between the inner and middle layers, creating a pocket called a “false lumen.” As this pocket fills, it balloons inward and narrows the true channel where blood is supposed to flow.
The narrowing itself can reduce blood flow to the brain, but the bigger danger is what happens at the tear site. Blood pooling in the damaged area tends to clot, and pieces of that clot can break off and travel into smaller brain arteries, blocking them entirely. That’s how a dissection causes a stroke.
Where the Artery Is Most Vulnerable
Each vertebral artery travels from the base of the neck up through small bony tunnels in the vertebrae of the spine before entering the skull. Anatomists divide this path into four segments, labeled V1 through V4. The stretch between the top two vertebrae (C1 and C2) is the most common location for compression and dissection. At that level, the artery is relatively mobile and exposed as it loops around the uppermost vertebra before piercing through the membrane that surrounds the brain. That combination of mobility and sharp turns makes it susceptible to mechanical stress.
Common Causes and Triggers
VAD falls into two broad categories: traumatic and spontaneous. Traumatic dissections result from a direct injury or forceful movement of the neck. Car accidents, sports collisions, roller coasters, and even vigorous coughing or sneezing can generate enough force. Activities that involve sudden neck rotation or extension, like certain martial arts moves or overhead work, have also been linked to dissections. Cervical manipulation during chiropractic treatment is a recognized, though debated, trigger.
Spontaneous dissections happen without an obvious injury, and they point to an underlying weakness in the artery wall. People with heritable connective tissue disorders like Ehlers-Danlos syndrome, Marfan syndrome, or fibromuscular dysplasia have structurally weaker blood vessel walls and face a higher risk. High blood pressure and a history of migraines are additional risk factors. In practice, the line between traumatic and spontaneous dissections is blurry. A genetically fragile artery may tear from a minor movement that would be harmless to someone with normal vessels, making it hard to pinpoint the exact cause.
What It Feels Like
The most common symptoms are dizziness or vertigo (reported in about 58% of cases), headache (51%), and neck pain (46%). About 76% of patients experience head or neck pain at some point during their presentation, which means roughly one in four people with a vertebral artery dissection have no pain at all, making it easy to miss.
When pain does occur, it tends to appear on the same side as the damaged artery. It typically starts suddenly, feels sharp and severe, and is described by patients as unlike any headache they’ve had before. The pain usually settles into a persistent ache that gradually fades over one to three weeks. Posterior neck pain, sometimes extending up to the back of the head, is the classic pattern. Two-thirds of patients report head or neck pain as their very first symptom, often days before any neurological signs develop.
That gap between the initial pain and later neurological symptoms is critical. A person might dismiss a sudden, severe neck pain as a muscle strain, only to develop signs of stroke hours or days later. Neurological symptoms depend on which part of the brain loses blood flow but commonly include vertigo, difficulty swallowing, slurred speech, double vision, loss of coordination, and numbness or weakness on one side of the body.
Wallenberg Syndrome: A Specific Complication
One of the most recognizable stroke patterns from a vertebral artery dissection is Wallenberg syndrome, also called lateral medullary syndrome. It happens when blood flow is cut off to a specific area in the lower brainstem. The hallmark symptoms are difficulty swallowing, a hoarse voice, persistent hiccups, double vision, vertigo, and a distinctive pattern of numbness: loss of pain and temperature sensation on one side of the face and the opposite side of the body. Balance and coordination problems are common. Symptoms often affect only one side, which can make them confusing to the person experiencing them.
How It’s Diagnosed
CT angiography (CTA) is the most reliable first-line imaging test. When compared against the gold standard of conventional angiography (an invasive test where dye is injected directly into the arteries), CTA detected 100% of vertebral artery dissections in pooled studies. MR angiography, which uses magnetic resonance instead of radiation, detected about 77%. Ultrasound picked up about 71%. Because of its speed, wide availability, and high sensitivity, CTA is typically the go-to choice in emergency settings where stroke is suspected.
MRI with special fat-suppression sequences can directly visualize the blood clot within the artery wall, which makes it a useful complement to CTA, especially for confirming the diagnosis or monitoring healing over time.
Treatment: Blood Thinners Are the Mainstay
The primary goal of treatment is preventing stroke by stopping clots from forming at the dissection site. This means blood-thinning medication, and the main clinical question has been whether antiplatelet drugs (like aspirin) or anticoagulants (like warfarin) work better.
Two major randomized trials tackled this question with somewhat different results. The CADISS trial found no significant difference between the two approaches in preventing stroke and death. The TREAT-CAD trial, however, failed to show that aspirin alone was as effective as anticoagulation. When data from both trials were pooled (444 patients total), the anticoagulation group had a lower rate of ischemic stroke within three months without an increase in bleeding complications. The combined analysis found a more than sixfold higher rate of stroke in the antiplatelet group compared to the anticoagulation group.
In practice, the choice between the two depends on individual factors like whether the patient has already had a stroke, the size of the dissection, and bleeding risk. Treatment typically continues for three to six months, after which the artery has usually healed enough to reassess.
Recovery and Recurrence Risk
Most people with a vertebral artery dissection recover well, particularly those diagnosed and treated before a major stroke occurs. The artery itself often heals over weeks to months as the body reabsorbs the clot within the vessel wall.
Recurrence is uncommon. A large meta-analysis of 29 studies found that about 4% of patients experienced a recurrent dissection overall. The risk was roughly 2% within the first month and 7% within the first year. When a recurrence did happen, the risk of it actually causing a stroke was about 2%. These numbers are reassuring, especially for younger, active patients who worry about returning to exercise and normal life after recovery. People with underlying connective tissue disorders may face a somewhat higher recurrence risk and are typically monitored more closely over the long term.