Fibromuscular Dysplasia (FMD)
Fibromuscular dysplasia (FMD) is a condition that causes narrowing (stenosis) and bulging of arteries of the body. These areas of narrowing and bulging occur right next to each other and often take on a “beaded” looking appearance. Over time this can cause severe narrowing of the artery impairing blood perfusion to the area of the body that the artery supplies. It occurs most commonly in the renal arteries (kidneys) but can also occur in arteries of the brain, abdomen, arms and legs.
The cause of FMD is not known but there are several suggested theories. Some experts believe there is a genetic component due to FMD being diagnosed in multiple members of the same family, including twins. FMD is more common in women than men and some researchers believe that hormones play in role in development of FMD. This is supported by the knowledge that FMD tends to be diagnosed in women who are primarily premenopausal. Others suggest that tobacco use could cause abnormal development of the arteries supplying blood to the vessel wall and this could cause inadequate delivery of oxygen to the artery resulting in the changes noted.
The signs and symptoms of FMD depend on the organ the affected artery supplies.
When the carotid and vertebral arteries are affected, patients may experience dizziness, blurring or loss of vision, vertigo, neck pain, ringing or swooshing noises in the ear (bruit), TIA or stroke. FMD patients are also at an increased risk for intracranial aneurysms.
Diagnostic imaging is the only means for diagnosing FMD. CT angiography, MR angiography, carotid duplex ultrasound and cerebral angiography are all effective ways to diagnose FMD.
The imaging for the most common form of FMD, medial fibroplasias, shows arteries with a distinctive look of a “string of beads” as opposed to a “straight tube-like appearance.”
There is no cure for FMD and there is not set a protocol or guidelines for treatment. Medical management is often the best form of treatment that can be offered and this is often done with measures to help increase and maximize blood flow and perfusion through the affected vessel.
Interventions can be offered but this is highly dependent on the vessel that is affected and the patient symptoms. Balloon angioplasty is most frequently used to open the carotid and renal arteries. Stents are not often used in treatment of FMD due to the disease being diffuse within the artery and often times not focal. It is typically recommended that people with FMD use some form of antiplatelet agent on a daily basis (usually aspirin or clopidogrel).