What is cervical artery dissection?

There are four main arteries that supply blood flow to the brain. Two carotid arteries and two vertebral arteries. The carotid arteries can be felt on each side of the lower neck, immediately below the angle of the jaw. The vertebral arteries are located in the back of the neck near the spine and cannot be felt on physical exam.  

The artery walls are made up of three layers of different types of tissue, each with a specific function. Dissection occurs when a tear in the artery wall allows blood to leak between the layers and separate them. The effect has been described as what happens to a piece of plywood that gets wet.

Cervical artery dissection is a dissection of any of the arteries in the neck.  It can involve a carotid or vertebral artery and sometimes multiple arteries can be involved.

What causes cervical artery dissection?

Certain medical conditions such as Marfan or vascular Ehlers-Danlos syndromes – types of genetic connective tissue diseases – fibromuscular dysplasia or atherosclerosis (the accumulation of fatty plaque in the artery walls) put individuals at risk for developing cervical artery dissection. Cervical artery dissection in these patients is called "spontaneous," meaning that it occurs without trauma to the head or neck.

Cervical artery dissection also can occur in the general population as a result of blunt trauma injury to the neck, such as a high-speed car accident or a fall, with chiropractic manipulation, or from hyperextension of the neck in sports or exercise. Cervical artery dissection has also been reported after heavy weight lifting.  

High blood pressure and smoking increase the risk of cervical artery dissection. Some cases of cervical artery dissection also have been reported after invasive diagnostic procedures.

How does cervical artery dissection develop?

Cervical artery dissection begins as a tear in one layer of the artery wall. Blood leaks through this tear and spreads between the layers of the wall. As the blood collects in the area of the dissection, it forms a clot that limits blood flow through the artery. If the clot is large enough to completely block blood flow, this can result in a stroke. Equally dangerous, pieces of the clot can break off and travel up through the bloodstream, limit the blood flow to the brain and cause a stroke.

Depending on where the dissection occurs in the artery, it may cause the artery to bulge in the area where the blood is pooling. This bulging, blood-filled area is called a pseudoaneurysm. If within the brain, these can be fragile and carry a risk of breaking and causing bleeding around the brain (called a subarachnoid hemorrhage); however if in the neck, these rarely break, though they may produce symptoms by pressing on surrounding structures.  Sometimes pseudoaneurysms can form after the initial artery dissection.