Fibromuscular dysplasia (FMD) is an arterial disease that causes abnormal fibrous tissue in the artery wall, leading to narrowing (stenosis), dilation (aneurysm), and/or tearing (dissection). The most common form of FMD (known as medial fibroplasia or multifocal disease) is described as a "string-of-beads" due to alternating areas of artery stenosis and dilation. Less common forms (intimal or unifocal) appear as a single area of stenosis that may be mistaken for cholesterol plaque.
FMD can affect any artery, although the neck arteries that supply the brain (carotid and vertebral arteries) and the renal arteries that supply the kidneys are most often involved. The majority of FMD is a disease of middle-aged women, although patients of any age and sex can be affected.
Fibromuscular Dysplasia Causes and Risk Factors
The underlying cause of FMD is unknown, although there is almost certainly a genetic contribution to the disease. However, a specific gene has not been identified.
Mount Sinai has a number of research studies aimed at improving our understanding of FMD. Visit Mount Sinai's Clinical Trials website to learn more
Because the cause of FMD is unknown, there are no recommendations for prevention. However, there are situations in which the diagnosis of FMD should be considered:
- Patients ages 35 or younger with high blood pressure
- Patients with severe recurrent headaches (especially migraine)
- Patients with pulsatile tinnitus
- Patients with a dissection or aneurysm
- Stroke in a person under the age of 60
- All patients should ask that their doctor listen over the neck and abdomen with a stethoscope for a bruit (an abnormal sound); if present, an ultrasound should be performed
The general recommendations of blood pressure control, avoiding tobacco, and cholesterol and blood sugar control will promote vascular health in all patients regardless of FMD.
Fibromuscular Dysplasia Symptoms
Symptoms of FMD depend on the arteries affected. Carotid and vertebral disease may cause headache (especially migraine type), dizziness, or a "whooshing" noise in the ear (pulsatile tinnitus). Renal artery involvement often results in high blood pressure.
Many patients have no symptoms at all, and FMD is found incidentally. A high suspicion is needed because many FMD symptoms are not specific and can been seen in other conditions that affect the same age group.
Severe cases of FMD-associated aneurysm or dissection may result in stroke (weakness on one side of the body, speech difficulty, loss of vision in one eye), damage to the kidney, heart attack, obstructed blood flow to the leg causing claudication (pain or fatigue with walking in one limb that improves with rest) or gangrene. Up to 20 percent of FMD patients have a dissection and 20 percent have an aneurysm at diagnosis.
Diagnosing Fibromuscular Dysplasia
When FMD is suspected, the following may be considered to make the diagnosis:
- Carotid and renal artery ultrasounds are appropriate screening tests. This is a non-invasive technique that evaluates the blood vessels. Experienced centers, such as Mount Sinai, can evaluate the entire artery and identify FMD.
- Catheter-based angiogram involves placement of a catheter in the groin that is fed up to the artery of interest for the manual injection of contrast. This provides accurate artery images and allows for use of tools that can measure the severity of the stenosis and treatment of stenosis, aneurysm, and/or dissection.
- Magnetic resonance (MR) and computed tomography (CT) angiogram combine the use of a contrast agent with three-dimensional (3D) images created by magnetic waves or CT respectively that are very accurate. Given the high rate of aneurysm in this population, all patients with FMD may benefit from a one-time screening with CTA or MRA of the head, neck, chest, abdomen, and pelvis.
Fibromuscular Dysplasia Treatments
All patients with FMD should be seen by a vascular specialist for long-term care and follow-up. Management is directed at symptom control and prevention of complications. At Mount Sinai, we recommend:
- Medical therapy, including aspirin 81-325 mg to prevent stroke and heart attack
- Strict blood pressure control to reduce stress on artery walls
- Surveillance imaging every six to 12 months with carotid and renal ultrasound to monitor disease stability
- Screening for aneurysms with CT or MR angiogram
In appropriate cases, minimally invasive procedures with a balloon or placement of mesh tube (stent) in the artery to correct an area of narrowing, dissection, or aneurysm. Rarely, surgery is necessary to repair an aneurysm. This is determined on a case-by-case basis by the vascular specialist.
Division of Vascular and Endovascular Surgery
Vascular Interventions – Cardiac Cath Lab
1190 Fifth Avenue, 1st Floor
New York, NY 10029
Mount Sinai physicians were able to diagnose and treat Karen's fibromuscular dysplasia and save her kidneys. Learn more about Karen's story