Fibromuscular dysplasia (FMD) is a condition that causes extra cells to grow inside the walls of arteries. Arteries are blood vessels that carry blood from your heart to the rest of your body. The extra cell growth narrows the arteries, allowing less blood to flow through them. It can also lead to bulges (aneurysms) and tears (dissections) in the arteries.

FMD typically affects medium-sized arteries that supply blood to the:

  • kidneys (renal arteries)
  • brain (carotid arteries)
  • abdomen or intestines (mesenteric arteries)
  • arms and legs

Reduced blood flow to these organs can lead to permanent damage.

FMD affects between of Americans. About one-third of people with this condition have it in more than one artery.

FMD doesn’t always cause symptoms. When it does, the symptoms depend on which organs are affected.

Symptoms of reduced blood flow to the kidneys include:

Symptoms of reduced blood flow to the brain include:

Symptoms of reduced blood flow to the abdomen include:

Symptoms of reduced blood flow to the arms and legs include:

  • pain in the affected limb when walking or running
  • weakness or numbness
  • temperature or color changes in the affected limb

Doctors aren’t sure what causes FMD. However, researchers have settled on three main theories:

Genes

About of FMD cases occur in members of the same family, suggesting genetics may play a role. However, just because your parent or sibling has the condition doesn’t mean you’ll get it. In addition, family members can have FMD that affects different arteries.

Hormones

Women are more likely to get FMD than men are, which suggests that female hormones may be involved. However, more research is needed to confirm this.

Abnormal arteries

A lack of oxygen to the arteries while they’re forming could cause them to develop abnormally, leading to decreased blood flow.

While the exact cause of FMD is unknown, there are a few factors that may increase your chance of developing it. These include:

  • being a woman under the age of 50
  • having one or more family members with the condition
  • smoking

Your doctor might suspect that you have FMD after hearing a swooshing sound when listening to your artery with a stethoscope. In addition to evaluating your other symptoms, they may also use an imaging test to confirm your diagnosis.

Imaging tests used to diagnose FMD include:

  • Duplex (Doppler) ultrasound. This test uses high-frequency sound waves and a computer to create images of your blood vessels. It can show how well blood is flowing through your arteries.
  • Magnetic resonance angiography. This test uses powerful magnets and radio waves to create pictures of your blood vessels.
  • Computed tomography angiography. This test uses X-rays and contrast dye to produce detailed images of your blood vessels.
  • Arteriography. If noninvasive tests can’t confirm the diagnosis, you might need an arteriogram. This test uses a contrast dye injected through a wire placed in your groin or the affected part of your body. Then, X-rays are taken of your blood vessels.

There’s no cure for FMD, but you can manage it. Treatments can help you to manage your symptoms and prevent complications of the disease.

Many people find some degree of relief from blood pressure medications, including:

You may also need to take blood thinners, such as aspirin, to prevent blood clots. These make it easier for blood to pass through narrowed arteries.

Additional treatment options include:

Percutaneous transluminal angioplasty

A thin tube called a catheter with a balloon at one end is threaded into the narrowed artery. Then, the balloon is inflated to keep the artery open.

Surgery

If you have a blockage in your artery, or your artery is extremely narrow, you may need surgery to fix it. Your surgeon will either remove the blocked part of your artery or reroute blood flow around it.

FMD is usually a life-long condition. However, researchers haven’t found any evidence that it decreases life expectancy, and many people with FMD live well into their 80s and 90s.

Work with your doctor to find the best way to manage your symptoms, and make sure to tell them if you notice any new symptoms, including:

  • vision changes
  • speech changes
  • unexplained changes in your arms or legs