Fibromuscular dysplasia


Vascular disease that most commonly affects the renal and internal carotid arteries but can be present in any artery.

A multiregional arteriopaathy that affects younger patient population than typical atheromatous disease.

Fibromuscular dysplasia is an idiopathic arteriopathy not caused by underlying atherosclerosis or inflammation, with a predilection for medium-sized vessels. 

Characterized by proliferation of intramural cells and deposition of loose, disorganized collagen in the arterial media.
Collagen deposition generates fibromuscular ridges which are areas of arterial stenosis alternating with areas of arterial dilatation caused by focal cellular loss.

The alternating stenoses and dilatations produce the characteristic beads on a string appearance of fibromuscular dysplasia on angiography.

It is the hallmark feature on imaging (“string of beads)”, which occurs where areas of fibrosis causing narrowing, alternating  with regions of dilation.

Most often affects the renal arteries, but the carotid, vertebral, mesenteric, coronary, or extremity arteries are vulnerable, also.

Typical manifestations include: aneurysm, stenosis, and  arterial dissection.

A non-atherosclerotic vasculopathy characterized by fibroplasia of the small or medium sized arteries.

Approximately 20% of patients with fibromuscular dysplasia have an arterial  dissection with cervical and renal arterial dissection being the most common.

It is the condition most commonly associated with spontaneous coronary artery dissection with an estimated prevalence of 25% to 86%.

May be asymptomatic or a multisystem process resembling a vasculitis.

Of unknown etiology.

Typically affecting the medium and large arteries of young to middle-aged women.

It is much more common in women.

A noninflammatory, nonatherosclerotic arterial disease.

It is usually multifocal, and the distinctive string of beads manifestation results from alternating areas of stenosis and small aneurysms.

Ninety percent of patients are female.

Mean age at diagnosis of approximately 52 years.

It is estimated to affect 4% of the population, 7% of cases are familiar.

Patients of any age may be affected.

Fibrous tissue in the arterial wall may lead to stenosis, aneurysm, embolization, and/or dissection.

May be an asymptomatic process, but usually manifests as renovascular hypertension, tinnitus, dizziness, transient ischemic attack or stroke.

When symptoms occur, they corresponding to the involved vascular beds.

Vertebral or carotid FD can cause headache and pulsatile tinnitus, or in severe cases, cranial nerve palsies and focal neurological deficits.

In mesenteric FD chronic ischemia may develop, resulting in postprandial abdominal pain, weight loss, and epigastric bruit.

Renovascular hypertension is the most common sequelae renal artery disease.

Usually associated with a 4- to 9-year delay in diagnosis from onset of the first symptom or sign of disease, because of the rarity and unfamiliarity of associated symptoms.

Dissection of an aneurysm can lead to stroke, subarachnoid hemorrhage, myocardial infarction, and hemoperitoneum.

Patients rarely die with FD ascilar complications, with a documented rate of 0.8%.

The diagnosis is considered in the following circumstances: resistant hypertension, new onset of hypertension in patients younger than 35 years, presence of epigastric or subcostal bruit with hypertension, cervical bruit, transient ischemic attack, stroke, or aortic aneurysm in patients younger than 60 years, dissection of a peripheral artery, aneurysm of a visceral or intracranial artery, pulsatile tinnitus, severe and recurrent migraine headaches, renal infarction, or subarachnoid hemorrhage.

Associated with a high prevalence of aneurysms, approximately 20%.

Associated with a high prevalence of arterial dissections, about 20%.

Above data suggests that patients with fibromuscular dysplasia should have imaging of the carotid, vertebral, and intracranial arterial circulations, as well as CT scan of the chest abdomen and pelvis or magnetic resonance angiography to rule out seriou associated vascular abnormalities.

Typically affects renal arteries in 85% of patients with presentation of renovascular hypertension.

Internal carotid arteries second most common site of involvement and is bilateral in 65% of patients.

May present with cerebral ischemia, TIA or thrombotic stroke, 20%, 29% and 6% of the time, respectively.

Associated with intracranial aneurysms in about 30% of patients and spontaneous carotid artery dissection in 10-20% of cases.

One third of patients with carotid disease also have renal artery involvement.

10% of patients with carotid disease have vertebral artery involvement.

Lumbar, mesenteric, celiac hepatic and iliac arteries may be involved.

May be associated with alpha-1-antitrypsin deficiency.

Classified by intimal, medial or subadventitial fibroplasias, with the medial type most common associated with angiographic findings of “string of beads”..

Female to male ratio 3:1.

Typical presentation ages 25-50 years.

Incidence in adults is 0.6% with angiography and 1.1% at autopsy.

Treatment consists of symptom management and prevention of vascular events.

Ultrasound is the recommended screening test with a high sensitivity in detecting stenosis.

CT or MRI is needed to confirm the diagnosis.

If noninvasive tests are negative, but clinical suspicion persists, catheter based angiography is considered.

Patients diagnosed with renovascular disease should undergo screening for extracranial carotid or vertebral involvement as 60% of patients with renal involvement also have extra cranial carotid or vertebral involvement, and women are 1.7 times more likely than men to have extracranial carotid involvement.

Aspirin is recommended due to the presence of turbulent flow from intraluminal fibrous tissue producing stenosis and potential for emboli.

Angioplasty is reserved for those with uncontrolled hypertension medications.

Management consists of imaging surveillance, as well as medical endovascular and surgical treatments.

Surveillance with non-invasive imaging should occur at 6-12 month intervals in patients with vertebral and carotid disease.

ACE inhibitors are preferable for patients with hypertension induced by FD, and aspirin is recommended to prevent thromboembolic events.

Revascularization can be done by th e vascular or surgical approaches, and generally are reserved for refactory or advanced cases.

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