Most people have never heard of the blood vessel disorder known as fibromuscular dysplasia (FMD), but doctors now recognize that it can be a hidden cause of high blood pressure (hypertension), strokes and brain aneurysms (due to bulging in the wall of an artery in the brain).

Recent development: Once considered a rare condition, FMD now appears to be more common than previously thought, possibly affecting up to 5 million adults in the US.

What you need to know…

What Is FMD?

In people with FMD, abnormal cell growth occurs on the walls of one or more arteries (blood vessels), typically in the carotid (neck) arteries (leading to the brain and renal arteries (leading to the kidneys). The normally smooth artery wall develops bumps, often resulting in a "string of beads" that can be seen on imaging tests used to examine blood vessels, such as ultrasound, a computed tomography angiogram (CTA) or magnetic resonance angiogram (MRA).

When cell growth becomes extensive, the artery narrows, disrupting blood flow and possibly resulting in hypertension, a stroke or an aneurysm. While atherosclerosis-fatty buildup in the arteries-occurs at the opening of a blood vessel, FMD occurs at the middle and end of a blood vessel.

Are You At Risk?

Though FMD typically strikes adults under age 50, doctors now are finding more and more previously undiagnosed cases in people age 60 and older perhaps due to the increasing use of imaging tests. FMD often is diagnosed as a result of an incidental finding on an unrelated radiological test. In many of these cases, the patient has no symptoms of the disorder.

No one knows what causes FMD. Genetics may play a role, but not everyone with FMD has a relative with the disease. FMD occurs more often in women (about 85% of cases) than in men. Researchers suspect that a gene predisposes an individual to the condition and that the gene is expressed due to outside influences, such as hormones.

Getting A Proper Diagnosis

FMD often goes undiagnosed because many doctors mistakenly believe that it is very rare. In fact, many medical schools don't even teach their students about FMD.

To complicate matters further, many people with FMD have no symptoms. When symptoms do occur, they are related to the arteries that are affected and the degree of narrowing that has developed.

Example: Since the majority of FMD cases occur in the arteries leading to the kidneys, high blood pressure may develop (due to narrowing of the renal arteries, which triggers a series of adverse effects). Abnormal kidney function and flank pain (occurring on one side of the body between the upper abdomen and the back) also can occur.

In about 25% to 30% of FMD patients, the disease affects the carotid arteries. In these people, symptoms may include severe and unrelenting headaches.. dizziness...ringing in the ears (tinnitus).. and neck pain.

FMD in the carotid artery also may lead to a swishing sound in the ears...temporary or permanent loss of vision in one or both eyes... brain aneurysms...and transient ischemic attacks (TIAs)-or "mini-strokes" as well as full-blown strokes.

Though less likely, FMD can affect the arteries supplying the liver, spleen and intestines, which may cause abdominal pain after eating, unexplained weight loss or gangrene of the bowel. If the arteries to the legs or arms are affected, pain or fatigue when using the affected limb can occur. In very rare cases, FMD may affect the coronary arteries in the heart, leading to angina (chest pain) or a heart attack.

Helpful: Regardless of your age, ask your doctor during all routine physicals to place a stethoscope on your neck and abdomen and listen for a bruil, a noise that indicates a narrowing of a blood vessel. If a bruit is heard, your doctor can follow up with the appropriate test, such as an ultrasound or CTA.

Important: Not all FMD patients have an audible bruit.

Best Treatment Options

FMD has no cure. The goal is to improve blood flow in the affected artery. Treatment depends on which artery is narrowed and the severity of the symptoms. Medication that alleviates high blood pressure, such as an angiotensin-converting enzyme (ACE) inhibitor, may be prescribed. Many patients take daily aspirin to help prevent clots from forming, thus reducing stroke risk.

FMD patients who have "new-onset" hypertension may require percutaneous transluminal renal angioplasty (PTRA). This procedure (usually outpatient involves inserting a catheter into the affected artery and inflating a small balloon to open the narrowed area.

Important finding: A study published in the Journal of Vascular Surgery showed that renal artery angioplasty reduced high blood pressure in 72% of the 29 FMD patients studied and the reduction was still evident five years after the procedure.

Finding The Right Doctor

If you have FMD—or suspect that you may—see a vascular specialist or a plıysician who is experienced in treating the organ affected by the disease.

For example: A nephrologist (kidney doctor) if FMD affects your renal arteries (or you are having kidney problems such as those described above)...or a neurologist if the carotid arteries are affected.

Cutting-Edge Research on FMD

Several medical centers in the US, including the Mount Sinai Medical Center in New York City and the Cleveland Clinic, participate in an international registry of FMD patients to help scientists conduct cutting-edge research to unravel some of the mysteries of the disease.

If you or a family member has been diagnosed with FMD, contact the Fibromuscular Dysplasia Society of America (FMDSA), 888709-7089,, which can provide information about the registry closest to you.

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