Fibromuscular Dysplasia and Stroke

What Is Fibromuscular Dysplasia?

Narrowing of the carotid artery. ADAM

Fibromuscular dysplasia (FMD) is a disease in which a short segment of a blood vessel (typically an artery) is narrowed by abnormal growth on its wall. This is caused by a process known as “fibromuscular hyperplasia.” FMD can affect any blood vessel in the body, but most commonly it affects the blood vessels that bring blood to the kidneys and the brain. When FMD affects blood vessels that feed the brain, it can lead to a stroke.

Symptoms of FMD in the Brain:

Very often people with FMD do not feel any symptoms. However, once the abnormal growth of the blood vessel wall affects blood flow to a part of the brain, a person may feel headaches, neck aches, ringing in the ears, lightheadedness, vertigo and nausea. They may also transiently stop seeing through one or both eyes, or even experience repeated bouts of loss of consciousness. Unfortunately in many cases, the first symptom of FMD is a transient ischemic attack or a stroke.

What Causes FMD?

Scientists have linked FMD with genes, hormones, and other factors, but the cause of FMD is still unknown. People at increased risk of FMD include:

How Is FMD Diagnosed?

There are several tests used to diagnose FMD, but the two most common ones are:
  • Duplex ultrasonography: This test measures the velocity of blood as it goes through a blood vessel. In blood vessels affected by FMD, blood flow velocity is increased as it rushes past narrow areas where the blood vessel wall is thickened by FMD.
  • CT angiography: This test involves the injection of a contrast dye into the area of the blood vessel affected by FMD. This contrast dye appears bright in an X-ray, so that bright areas represent the shape of the inside of the vessel of interest. The typical shape of blood vessels affected by FMD on CT angiography is referred to as a “string of beads,” because the bright areas on a CT scan, or CAT scan in fact look like a string of beads.

    How Is FMD Treated?

    Several techniques are used to reopen blood vessels affected by FMD. The most common ones include:
    • Percutaneous angioplasty and stenting: In this procedure, a special wire known as an “angiography catheter” is inserted into a blood vessel in the groin and directed all the way into the area of a blood vessel that is affected by FMD. Once there, a balloon which is connected to the tip of the catheter is slowly inflated, causing the narrow area of the vessel to expand. Sometimes, a special wire mesh called a stent is also placed in the area to prevent the same area of the blood vessel from being affected again by FMD.
    • Resection and anastomosis: This is a surgical procedure in which the affected area of the vessel is surgically removed.
    • Autograft placement: This surgical treatment of FMD involves the removal of the affected part of the vessel, and its replacement with a small segment of a vein previously harvested, typically from the leg.
    • Carotid endarterectomy: This procedure is performed to re-open the carotid artery when it is narrowed as a result of a variety of diseases, one of which is FMD. This type of surgery involves the manual removal of the blood vessel area which prevents normal blood flow.

    Read more about carotid artery occlusion and its treatment.

    David P. Slovut, M.D., Ph.D., and Jeffrey W. Olin, D.O. Fibromuscular Dysplasia, New England Journal of Medicine, 2004, 350:1862-1871

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