What is fibromuscular dysplasia (FMD)?

Fibromuscular dysplasia (FMD) is the abnormal development or growth of cells in the walls of arteries, causing the vessels to narrow or bulge. The carotid arteries, which pass through the neck and supply blood to the brain, are commonly affected. Arteries within the brain and kidneys can also be affected. A characteristic-string of beads- pattern caused by the alternating narrowing and enlarging of the artery can block or reduce blood flow to the brain, causing a stroke or a mini-stroke. Some patients experience no symptoms of the disease, while others may have high blood pressure, dizziness or vertigo, chronic headache, intracranial aneurysm, ringing in the ears, weakness or numbness in the face, neck pain, or changes in vision. FMD is most often seen in person's age 25 to 50 years and affects women more often than men. More than one family member may be affected by the disease. The cause of FMD is unknown. An angiogram can detect the degree of narrowing or obstruction of the artery and identify changes such as a tear (dissection) or weak area (aneurysm) in the vessel wall. FMD can also be diagnosed using computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound (USG) scans.

This answer from the National Institute of Neurological Disorders and Stroke has been reviewed and/or edited by Dr. William D. Knopf.