Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory disease of the blood vessels that causes abnormal growth within the wall of an artery. FMD has been found in nearly every arterial bed in the body although the most common arteries affected are the renal and carotid arteries.

Signs and symptoms

The symptoms expressed by FMD patients is largely dependent on the vascular bed(s) affected by the disease. Patients may also be entirely asymptomatic and have FMD discovered incidentally (e.g., when imaging studies are performed for other reasons). In a study from the United States Registry for Fibromuscular Dysplasia, the median age at first symptom was roughly 47 years.

Renal arteries The main symptoms associated with renal FMD are secondary hypertension and bruits that can be heard with a stethoscope over the abdomen or flanks. Complications such as aneurysms, dissections, or occlusion of the renal artery have been associated with renal artery FMD.

Cerebrovascular regions The carotid and vertebral arteries are most commonly affected. Middle and distal regions of the internal carotid arteries are frequently involved. Patients with FMD in the carotid arteries typically present around 50 years of age. Symptoms of craniocervical involvement include headaches (mostly migraine), pulsatile tinnitus, dizziness, and neck pain, although patients are often asymptomatic. On physical examination, one may detect neurological symptoms secondary to a stroke or transient ischemic attack (TIA), a bruit over an affected artery, and diminished distal pulses. Complications of cerebrovascular FMD include TIA, ischemic stroke, Horner syndrome, or subarachnoid hemorrhage.

Other sites Patients with mesenteric, or intestinal FMD, may experience abdominal pain after eating or weight loss. FMD within the extremities may cause claudication or may be detectable by bruits. If the lower limb arteries are affected, the patient may present with cold legs or evidence of distal embolic disease. FMD present in the subclavian artery may cause arm weakness, parenthesis, claudication, and subclavial steal syndrome.

Children Children with FMD often report various non-specific symptoms or present with hypertension during routine physical examinations. Symptoms are commonly associated with the artery being affected. Symptoms may include headaches, insomnia, fatigue and chest or abdominal pain. FMD affecting the arteries of the head neck are commonly recognized as a cause of childhood strokes.Detection may stem from a bruit being present over the affected vascular bed during a physical assessment. Yet, absence of a bruit does not rule out significant vascular disease.In children, renovascular disease accounts for approximately 10% of all causes of secondary hypertension. Kidney failure is a common presentation in infants and children but is uncommon in adults, although it is occasionally the presenting problem in adults with focal disease.“The presentation in infants and children younger than 4 years is especially likely to resemble vacuities.”

Related diseases The vascular subtype of Ehlers-Danlos Syndrome (type IV) has been associated with multi-focal FMD. This syndrome should be suspected in patients with multiple aneurysms and/or tears (dissections) in arteries in addition to the typical angiographic findings of FMD. There have been isolated reports of FMD associated with other disorders, including Alport syndrome, pheochromocytoma, Marfan syndrome, Moyamoya disease, and Takayasu's arteritis

Diagnosis FMD is currently diagnosed through the use of both invasive and non-invasive tests. Non-invasive testing includes duplex ultrasonography, magnetic resonance angiography (MRA), and computed tomography angiography (CTA).

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Atherosclerosis : Open Access