Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory disease of the arteries most commonly involving the kidneys (renal arteries) and neck (carotid arteries). The disease typically presents in women around age 40, but it can occur in all age groups and also in men. Hypertension is the most common presenting finding, although patients may have a variety of symptoms including headaches, dizziness, and in some cases strokes are possible.
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.
Causes
The cause of FMD is still unknown. However, several factors may play a role in its development. A combination of these factors is likely responsible –
- Genetics – Research suggests that about 10% of cases appear in families. People who have a family member with FMD may develop the condition in different arteries than their relative, experience a more or less severe version of the disease, or may not develop FMD at all
- Hormones – FMD is three to four times more common in premenopausal women than in men, suggesting that sex hormones may be involved in its development
- Abnormal arteries – A lack of oxygen to the artery walls may cause them to form abnormally. Arteries may also be located abnormally within the body, predisposing them to FMD
Risk Factors
- Sex – Women have a much greater risk of fibromuscular dysplasia than do men.
- Age – Fibromuscular disorder tends to be diagnosed in people in their early 50s.
- Smoking – People who smoke appear to have an increased risk of developing fibromuscular dysplasia. For those already diagnosed with the disease, smoking is a risk factor for more serious fibromuscular dysplasia.
- Family history – FMD appears to have a genetic basis. About 10% of people with FMD have a relative with the condition
Symptoms
In many cases, fibromuscular dysplasia is asymptomatic (i.e., does not cause symptoms). When symptoms do occur, they depend on which artery or arteries are affected and on the severity of the condition. Severe stenosis can cause pain in the area of the body that is supplied by the affected artery.
Fibromuscular dysplasia that develops in the arteries that supply blood to the kidneys (renal arteries) may cause high blood pressure (hypertension) and kidney damage (e.g., ischemic nephropathy). In severe cases, kidney failure can occur.
When fibromuscular dysplasia develops in the arteries that supply blood to the brain (carotid arteries), the condition can cause neurological symptoms, including the following:
- Blurred vision or vision loss
- Dizziness (vertigo)
- Headache
- Neck pain
- Ringing in the ears (tinnitus)
Fibromuscular dysplasia that affects the carotid arteries can cause serious complications, such as stroke or brain attack, transient ischemic attack (TIA, “ministroke”), dilation of a blood vessel in the brain (intracranial aneurysm), bleeding in the brain (intracranial hemorrhage), and dissection (tearing) of the blood vessel (e.g., aortic dissection).
When the arteries that supply blood to the gastrointestinal (GI) tract and other abdominal organs (e.g., liver, spleen) are affected by fibromuscular dysplasia, patients may experience abdominal pain and other digestive disorders and weight loss.
Fibromuscular dysplasia that reduces blood flow in the arteries that supply the arms and legs can cause pain, weakness, numbness, and tingling in the extremities and peripheral neuropathy.
Complications
- High blood pressure – When the arteries become narrowed, blood pressure can increase. High blood pressure (hypertension) is the most common complication of FMD
- Stroke – A stroke may occur if an aneurysm in one of the carotid arteries ruptures or if one of the carotid arteries dissects, disrupting the flow of blood to the brain
- A tear in the artery (dissection) -The lining of the artery wall may tear, causing blood to leak into the wall
- Aneurysm – The pressure of blood flow through a narrowed artery can create a weakened area or bulge in the artery wall called an aneurysm. An aneurysm may rupture, resulting in a life-threatening situation
- Pain or cramping in lower legs (intermittent claudication) – FMD that affects the arteries in the legs can cause discomfort or pain when walking and exercising
- Kidney dysfunction or failure – Reduced blood flow to the kidneys can impair kidney function and, in rare cases, lead to kidney failure
Treatment
Medical therapy – The physician may prescribe medications to help control high blood pressure, including ACE inhibitors, beta blockers and calcium channel blockers. People with FMD may also need to take antiplatelet drugs, such as aspirin, to prevent blood clots
Interventional therapy – Physicians may use percutaneous transluminal angioplasty (PTA) to open narrowed sections of arteries. In this technique, a balloon-tipped catheter (thin, flexible tube) is threaded through the affected artery to expand it. PTA is less invasive than open surgery and results in faster recovery times
Surgery – This intervention re-routes blood flow around the diseased artery and may be used in severe cases or when PTA is not an option.
Genetic counseling – Because FMD appears to run in families, women of childbearing age may receive counseling for the genetic basis of the condition. There is not yet a genetic test for FMD.
Psychosocial treatment – FMD often affects young, otherwise healthy women, and coping with it can be difficult. Psychologists or other mental health professionals can offer counseling to help patients deal with the stress and anxiety that may accompany having FMD
Obstetrics/gynecological care – Specialists in obstetrics and gynecology can advise patients with FMD about the use of oral contraceptives, estrogen therapy and other hormone-based medications, which can affect blood flow in the arteries
Reference-
https://www.rareconnect.org/en/community/fibromuscular-dysplasia
http://www.nature.com/ki/journal/v75/n3/full/ki2008232a.html
https://www.inspire.com/groups/fibromuscular-dysplasia-society-of-america/
http://www.ninds.nih.gov/disorders/fibromuscular_dysplasia/fibromuscular_dysplasia.htm
http://circ.ahajournals.org/content/125/18/e636.full
http://www.fmdsa.org/fmd_info/what_is_fmd
http://www.massgeneral.org/vascularcenter/services/fibromusculardysplasia.aspx
http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Expert=336