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Fibromuscular Dysplasia

Practice Essentials

Fibromuscular dysplasia (FMD) is an angiopathy that affects medium-sized arteries predominantly in young women of childbearing age. Among patients with identified FMD, renal involvement occurs in 60-75%, cerebrovascular involvement in 25-30%, visceral involvement in 9%, and arteries of the limbs in about 5%.
FMD occurs in most other medium-to-large arteries as well, including the coronary arteries,
the pulmonary arteries,
and the aorta.
See the image below.

Angiogram of the descending aorta demonstrates the

Angiogram of the descending aorta demonstrates the stenoses of FMD in the renal arteries bilaterally.

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Signs and symptoms

Most patients with craniocervical FMD are asymptomatic. No particular symptoms are pathognomonic for FMD. Any history compatible with a stroke in younger individuals may indicate underlying FMD. The family history should include information about relatives who have had vascular events at a young age.

In symptomatic patients, manifestations of FMD may include the following:

Nonspecific problems, such as headache, light-headedness, vertigo, and tinnitus

Neck pain or carotidynia

History of transient or permanent neurologic deficits of the face or extremities (eg, weakness or numbness)

Visual changes or speech difficulties

Symptoms compatible with a sentinel bleed (eg, a sudden explosive headache followed later by neck stiffness): May indicate an aneurysm that may be associated with FMD

Symptoms suggestive of noncraniocervical FMD, such as hypertension (renal involvement), abdominal pains or a history of ischemic bowel (mesenteric or visceral artery involvement), or intermittent leg claudication (extremity artery involvement)

Physical examination should include the following:

Thorough neurologic examination

Neurovascular examination, including auscultation for carotid and vertebral artery bruits

General physical examination that includes a search for signs of renal, visceral, and extremity artery involvement

See Clinical Presentation for more detail.


Routine laboratory investigations are usually nonproductive but may show renal impairment.

Imaging considerations include the following:

A history of stroke or transient ischemic attack (TIA) in a young individual or a subarachnoid hemorrhage in a person of any age should prompt cerebrovascular imaging; such imaging is also indicated for any individual known to have FMD

Conventional angiography is standard for detecting FMD and its associated vascular lesions

Conventional cerebrovascular ultrasonography is unlikely to depict the carotid lesions of FMD

The sensitivity and specificity of computed tomography (angiography (CTA), time-of-flight (TOF) magnetic resonance angiography (MRA), or contrast-enhanced MRA (CE MRA) in this setting remain to be established

Conventional CT and MRI may be useful in finding ischemic strokes caused by arterial dissection or the FMD lesions themselves, as well as for detecting subarachnoid hemorrhage

Pathologically, FMD is classified into 3 main types, as follows

Intimal fibroplasia (< 10% of all cases of renal FMD)

Medial fibroplasia: Further classified into 3 subtypes: medial dysplasia (80% of renal cases and most carotid cases), perimedial fibroplasia (10-15% of all renal cases), and medial hyperplasia (1-2% of all renal cases)

Adventitial fibroplasia (< 1% of all renal cases)

Because these frequency figures are largely based on findings from renal studies, they may not reflect the distribution of FMD types in carotid disease.

See Workup for more detail.


Partly because of the unknown etiology of FMD, no curative therapy exists. Fortunately, FMD is often benign when asymptomatic, and medical treatment is not indicated. In symptomatic cases, management depends on the presentation, as follows:

Presentation with hypertension: The patient should be evaluated by a nephrologist and possibly considered for vascular intervention

Presentation as a TIA or ischemic stroke: If the patient presents within 3 hours of onset, consider intravenous tissue plasminogen activator (tPA); intra-arterial mechanical embolectomy and intra-arterial pharmacologic fibrinolysis may be considered to extend the acute treatment window to 6 hours; if tPA treatment is employed, avoid anticoagulants and antiplatelet agents for at least 24 hours

The diagnosis of FMD should be considered in any young individual presenting with a stroke or subarachnoid hemorrhage. Fortunately, cerebral angiography is the investigation of choice to detect not only FMD but also arterial dissection, vasculitis, and aneurysms, which are other major etiologies of stroke in this population. Thus, cerebral angiography should be performed if another cause for the stroke is not clear. The treatment options are influenced by the findings on angiography

Presentation with only FMD identified on angiography: Administer antiplatelet agents

Presentation with arterial dissection and FMD identified on cerebral angiography: Initially, focus on the dissection; consider anticoagulation after cerebral hemorrhage has been ruled out

Presentation with subarachnoid hemorrhage: Focus acute treatment on preventing rebleeding, arterial vasospasm, and further ischemic cerebral injury; close aneurysms; subsequently, manage conservatively unless further history is consistent with thromboembolic phenomena

Considerations for surgical treatment include the following:

Surgical vascular reconstruction of renal FMD has met with good success,
but the role of surgery in carotid and vertebrobasilar FMD is not well understood

With respect to stroke prophylaxis, the lesions in FMD are not amenable to endarterectomy; thus, surgical management is used as a last resort

A few cases with vascular graft placements and surgical bypass of FMD lesions have been reported

Aneurysms that may coexist with FMD should be managed in a similar manner to those that are not associated with FMD

Interventional radiologic management of FMD lesions may be suitable for some patients, especially those who are not good surgical candidates

See Treatment and Medication for more detail.

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