| Fibromuscular dysplasia | |
|---|---|
| Classification and external resources | |
The "string-of-beads" appearance of medial fibromuscular dysplasia on angiography. |
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| ICD-10 | I77.3 |
| ICD-9 | 447.3, 447.8 |
| OMIM | 135580 |
| DiseasesDB | 30163 |
| eMedicine | neuro/432 |
| MeSH | D005352 |
Fibromuscular dysplasia, or fibromuscular dysplasia of arteries, often abbreviated as FMD,[1] is a disease that can cause narrowing (stenosis) of arteries in the kidneys, the carotid arteries supplying the brain, and, less commonly, the arteries of the abdomen. FMD can cause hypertension, strokes, heart attacks, and arterial swelling (aneurysm) and dissection.
A few thousand cases have been confirmed in the U.S., but some experts believe it affects up to 5% of the population. When presumably healthy kidney donors are screened with X-rays, FMD has been found in close to 4%.[2][3]
In individuals with FMD, the cells in the walls of the arteries undergo abnormal growth. As a result, the inner passage of the vessels may become narrowed. This can cause symptoms if the blood flow is decreased enough. However, FMD is often diagnosed incidentally in the absence of any signs or symptoms during an imaging study. When the vessel is filled with dye for an X-ray, it will show a characteristic "string of beads" appearance.
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Fibromuscular dysplasia is an autosomal dominant[4] disorder. It tends to occur between 14 and 50 years of age, but it has also been found in children younger than age 14. In one study, women were found to be affected more often than men.[5]
Fibromuscular dysplasia is characterized by fibrous thickening of the intima, media, or adventitia of the artery. Up to 75% of all patients with FMD will have disease in the renal arteries. The lesions cause narrowing of the artery lumen. The second most common artery affected is the carotid artery, which is found in the neck and supplies the brain with blood. Less commonly, FMD affects the arteries in the abdomen (supplying the liver, spleen and intestines) and extremities (legs and arms). More than one artery may have evidence of FMD in 28% of people with this disease. All arteries should be checked if found.
As a result of renal artery stenosis, the kidney's afferent arteriolar pressure falls. The renin-angiotensin system is activated, causing fluid retention and hypertension. Symptoms of craniocervical involvement include headaches, pulsatile tinnitis, and lightheadedness, although patients are often asymptomatic. On physical examination, one may detect neurological symptoms secondary to a stroke or TIA, a bruit over an affected artery (usually appreciated over the costovertebral angle), and diminished distal pulses.
The preferred treatment for refractory cases is percutaneous balloon angioplasty. If the arterial wall is damaged or weakened, then stenting of the affected artery may be chosen. Besides high blood pressure control, anti-platelet drugs and blood thinner drugs may be used. Although renin and angiotensin are involved in the renal disease process ACE inhibitors, and Angiotensin II receptor antagonists are not treatments of fibromuscular dysplasia, as Angiotensin II-mediated vasoconstriction of the glomerular efferent arteriole aids in maintenance of adequate glomerular pressure (and thus, renal function) in the context of diminished afferent arteriole pressure.
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