Fibromuscular dysplasia is a vascular disease primarily affecting young adult women. This condition causes selected arteries to narrow, dissect, or develop an aneurysm, increasing the risk of stroke. With appropriate care, these complications can be largely avoided. But first, fibromuscular dysplasia must be diagnosed.
“Fibromuscular dysplasia is often missed or misdiagnosed as atherosclerotic cardiovascular disease (ASCVD) or vasculitis,” says Cleveland Clinic vascular cardiologist Pulkit Chaudhury, MD. “However, it has no connection to plaque or inflammation. For this reason, individuals who exhibit specific symptoms, fit the demographic profile, and have no risk factors for ASCVD should be screened for fibromuscular dysplasia.”
What Is Fibromuscular Dysplasia?
In fibromuscular dysplasia, the body deposits mesenchymal stem cells or a protein such as collagen in artery walls where they don’t belong. These abnormal deposits cause areas of the artery to become thick and stiff or thin and fragile. On imaging studies, an affected artery resembles a string of beads.
Fibromuscular dysplasia tends to affect medium-sized blood vessels, primarily the internal carotid arteries in the neck and the renal arteries in the kidneys. It also can be seen in the brachial arteries in the arms, the mesenteric arteries that supply blood to the gut, and the iliac arteries, which supply blood to the lower half of the body. “Investigation into whether fibromuscular dysplasia affects larger and smaller blood vessels is ongoing,” Dr. Chaudhury says.
Although fibromuscular dysplasia is diagnosed primarily in women in their 40s and 50s, it also occurs in children and in much older seniors. This raises the possibility that fibromuscular dysplasia might start at a younger age and exist long before it is diagnosed.
Fibromuscular Dysplasia Symptoms
In its early stages, fibromuscular dysplasia causes no symptoms. When symptoms appear, they tend to be:
- Hypertension, which affects up to 50% of individuals with fibromuscular dysplasia
- Headache
- Pulsatile tinnitus (a whooshing sound timed to your heartbeat)
When symptoms are absent, the first indication of fibromuscular dysplasia may be:
- Transient ischemic attack
- Stroke
- Dissected artery
- Ruptured aneurysm
Causes and Risk Factors
Fibromuscular dysplasia causes are not fully known, but plausible theories are being researched.
“Good data has emerged over the last three to five years suggesting fibromuscular dysplasia may be caused by a cluster of gene changes,” Dr. Chaudhury says. “We think that when certain gene modifications appear together, they manifest as fibromuscular dysplasia.”
Because more than one gene is involved, no genetic test for this disease is available. “Although we do see fibromuscular dysplasia in families, it’s not common enough to screen for it,” he adds.
Fibromuscular dysplasia also is theoretically linked to estrogen, which would explain its overwhelming presence in women. This connection has implications for the use of hormone replacement therapy (HRT). “Any woman with fibromuscular dysplasia should talk with her doctor about the forms of HRT that should be avoided,” Dr. Chaudhury says.
What isn’t known is how fibromuscular dysplasia may be connected with other connective tissue disorders. In the North American fibromuscular dysplasia registry, 5% of patients also have a coronary dissection. On the flip side, 40% to 50% of Dr. Chaudhury’s patients with coronary dissections also have fibromuscular dysplasia.
Fibromuscular Dysplasia Complications
After collecting data for more than a decade, fibromuscular dysplasia registries in North America and Europe are helping physicians better understand how the disease manifests in different ways. “We have learned that one in three fibromuscular dysplasia patients has a small aneurysm that needs to be monitored, has a small dissection in a medium-sized vessel, or needs a procedure of some sort,” Dr. Chaudhury says.
A dissection can immediately compromise blood flow through the artery. Depending on the artery affected, this problem can cause a stroke in the brain or kidney or a sudden elevation of blood pressure.
Over time, a dissection can evolve into an aneurysm. An aneurysm that ruptures is a traumatic event that can result in death. Dissections in patients with fibromuscular dysplasia rarely rupture, however. Instead, they make the lumen (the channel through which blood flows through an artery) smaller and may completely block it, potentially causing a stroke.
How Fibromuscular Dysplasia Is Diagnosed
In a large percentage of asymptomatic individuals, fibromuscular dysplasia is discovered incidentally on a scan taken for an unrelated reason. Sometimes, however, the first clue is a stroke, dissected artery, or aneurysm. For this reason, the possibility of fibromuscular dysplasia should be considered in otherwise healthy young adult women who exhibit symptoms consistent with fibromuscular dysplasia.
“A young middle-aged woman with no risk factors for ASCVD and no comorbidities but hypertension is likely to be given a clean bill of health,” Dr. Chaudhury says. “Because the bulk of patients with fibromuscular dysplasia have hypertension, at Cleveland Clinic we also screen young patients, particularly young women, with new-onset or difficult-to-control hypertension, as well as those with pulsatile tinnitus and hypertension-related headaches.”
Because it is difficult to distinguish fibromuscular dysplasia from ASCVD on ultrasound, a computed tomography angiogram (CTA) or magnetic resonance angiogram (MRA) is needed to diagnose fibromuscular dysplasia with confidence. Once the diagnosis has been confirmed, a cross-sectional head-to-pelvis scan is done to check for fibromuscular dysplasia in other locations.
“In a large percentage of individuals, fibromuscular dysplasia occurs in more than one location,” Dr. Chaudhury says. “Guidelines call for imaging all known vascular beds at the first visit, because everything we do from that point on depends on the size and location of the blood vessels involved and what the abnormality is.”
Fibromuscular Dysplasia Treatment
There is no cure for fibromuscular dysplasia, but with close surveillance and proper management, most complications can be prevented.
Aspirin or other antiplatelet medication is universally prescribed to help blood flow through the narrowed artery without clotting. Antihypertension medications are used to lower blood pressure.
Selected migraine medications can be given to help headache sufferers. “Some migraine medications increase the risk of dissection, especially in individuals with prior dissections, so we have to be cautious about which of these medications we prescribe for these patients,” Dr. Chaudhury explains.
Specific precautions are important for preventing dissections. “We advise patients to avoid heavy lifting, heavy isometric exercises, Valsalva maneuvers [in which you push air out but with your nose and mouth closed] and activities that cause whiplash, such as riding roller coasters, bungee jumping, and sky diving,” he says. Also, women should avoid tilting their head backward when getting their hair washed in a salon.
Sometimes angioplasty may be used to improve blood flow through a narrowed vessel and control blood pressure. Aneurysms may be treated with a catheter-based procedure or surgery to prevent rupture. Due to the abnormal architecture of these vessels, surgery to bypass the damaged areas is rarely done.
“A large percentage of patients with fibromuscular dysplasia never need an interventional procedure or surgery,” Dr. Chaudhury says.
When to Seek Medical Help
Anyone who experiences symptoms consistent with a stroke should call 911 immediately.
However, if you are told you have fibromuscular dysplasia following an imaging test or a doctor’s visit for hypertension, migraine, or pulsatile tinnitus, you are unlikely to need immediate emergency care. You may want to step back and consider your options before proceeding.
“Because most physicians have limited experience with fibromuscular dysplasia, do not hesitate to ask your doctor how comfortable they are providing care for the condition,” Dr. Chaudhury says. “Be mindful that there are few good reasons to do a catheter-based procedure for fibromuscular dysplasia, so if one is recommended, you would be wise to have it done in a place that regularly treats arteries with fibromuscular dysplasia, because complications are possible.
“Similarly, fibromuscular dysplasia can be misdiagnosed as ASCVD on modalities like ultrasound,” he continues. “If you are in your 50s or younger and have no family history of ASCVD or risk factors for it, and you are diagnosed with carotid artery disease, ask your doctor if they are confident about the diagnosis, particularly before agreeing to a procedure such as a carotid endarterectomy.”
Because so much about fibromuscular dysplasia is unknown, see a physician who is knowledgeable about the disease, preferably a vascular medicine specialist or vascular cardiologist. All medical centers in the United States with fibromuscular dysplasia specialists are listed on the Fibromuscular Dysplasia Society of America website (fibromusculardysplasia.org).
Appropriate, guideline-directed care for fibromuscular dysplasia requires an individualized, artery-specific surveillance plan that spells out the frequency of imaging required for monitoring the affected arteries and the imaging modalities that should be used.
“If you do not live close to a fibromuscular dysplasia center of excellence, aim for a single consultation with a fibromuscular dysplasia specialist. I think I speak for my colleagues when I say most of us are happy to see patients with fibromuscular dysplasia and advise their local physicians on how to monitor their condition,” Dr. Chaudhury says.
Many individuals are stressed by the diagnosis of fibromuscular dysplasia—Cleveland Clinic offers patients the option of seeing a psychologist to help them cope with the diagnosis. Once the initial shock wears off, however, simply learning that fibromuscular dysplasia may not be as dangerous as they feared can help soften the blow.
“Fibromuscular dysplasia tends to occur in younger women without other comorbidities, so they tend to live long, healthy lives,” Dr. Chaudhury says. “There is no reason to believe fibromuscular dysplasia will curtail their lifespan.”
