Vertebrobasilar insufficiency is a condition characterized by poor blood flow to the posterior (back) portion of the brain, which is fed by two vertebral arteries that join to become the basilar artery. Blockage of these arteries occurs over time through a process called atherosclerosis, or the build-up of plaque. Plaques are made up of deposits of cholesterol, calcium and other cellular components. They not only make the arteries ‘hard,’ they grow over time and can obstruct or even block the flow of blood to the brain.
The vertebrobasilar arteries supply oxygen and glucose to the parts of the brain responsible for consciousness, vision, coordination, balance and many other essential functions. Both restricted blood flow and the complete blockage of it — called ischemic events — have serious consequences for brain cells. Ischemia occurs when blood flow to the brain damages cells. An infarction occurs when the cells die. A transient ischemic attack (TIA), or “mini-stroke,” is an ischemic event that results in the temporary loss of brain function. If the resulting loss of brain function is permanent, it’ s called a stroke (an infarction or brain attack). A stroke can either be caused by blockage in the vertebral or basilar artery or the breaking off of a piece of plaque (embolus) that travels downstream and blocks a portion of the blood flow to the brain.
The vertebral arteries are branches of the subclavian (upper extremity) arteries. They arise, one on each side of the body, go through the vertebral column (spine) in the back of the neck, and enter the skull via the hole at the base of the skull called the foramen magnum. Inside the skull, the two vertebral arteries join up to form the basilar artery at the base of the medulla oblongata. The basilar artery supplies arterial branches to the brain stem, cerebella and occipital lobes, which control the autonomic nervous system (unconscious functions like breathing, heart rate, etc.), level of conscious, coordination, balance and vision.
A person with vertebrobasilar insufficiency (VBI) may experience symptoms lasting for a few minutes or permanent symptoms. These symptoms may include:
- Loss of vision in part or all of both eyes
- Double vision
- Vertigo (spinning sensation)
- Numbness or tingling
- Nausea and vomiting
- Slurred speech
- Loss of coordination, dizziness or confusion
- Trouble swallowing
- A drop attack — sudden generalized weakness
Because these symptoms may be warning signs of a stroke, anyone experiencing them should seek emergency medical care. Immediate treatment can increase the chance of a full recovery.
The risk factors for cerebrovascular disease are those associated with atherosclerosis:
- Hypertension (high blood pressure)
- Older age
- Gender: men have a higher risk before age 75; women have a high risk after 75
- Family history
- Genetic factors
- Hyperlipidemia (elevated fats in the blood)
Patients known to have atherosclerosis and diagnosed with coronary artery disease or peripheral artery disease are at greater risk for vertebrobasilar disease and stroke.
Studies of the vertebral and basilar arteries can be performed using magnetic resonance angiography (MRA) and standard angiography (X-ray study using injected dye). These are used to identify vertebrobasilar artery disease. A CT (X-rays and computer-generated 3-D images) or MR scan of the brain can be used to confirm that a stroke has already occurred.
Medication and lifestyle changes
Patients who have vertebrobasilar insufficiency, a history of stroke, or TIA (“mini-stroke”) should quit smoking immediately, attempt to lower cholesterol levels through diet, and exercise regularly. Physicians may also prescribe medication to control high blood pressure, lower blood cholesterol levels and block platelet function.
Location of the plaque causing the vertebrobasilar insufficiency will determine whether repair of the artery is possible. The further the plaque is from the brain, the more likely open surgical repair and/or endovascular repair will be considered as treatment options.
Open Surgical Repair
Three basic surgical procedures can be used to restore flow to the brain through the vertebral and basilar arteries. Bypass grafting involves placing a new blood vessel around the site of the narrowing. Direct arterial transposition involves moving a portion of the artery to an adjacent, healthy vessel and sewing the two together. Endarterectomy is the removal of the plaque from the affected artery. Hospital stays and recovery times vary, but are usually longer than with endovascular repair.
A newer technique called endovascular repair is used to treat vertebrobasilar insufficiency. It involves the placement of a catheter in an artery of the groin through a small nick in the skin. A balloon is advanced to the veterbral artery where it is inflated, expanding the artery wall. A tube-like metal stent may be inserted to keep the artery open and the blood flowing freely. Patients usually stay in the hospital for one or two days and quickly resume normal activities.