Fibromuscular dysplasia is a disease of the wall of medium-sized arteries, not related to atherosclerosis (cholesterol deposits) or inflammation.Typically, it may be at the origin of arterial narrowing (stenosis). It may also cause dilation (aneurysm), a tear (dissection) or tortuosity of the affected arteries.

FMD lesions are more commonly seen in the renal or cerebrovascular (head and neck) arteries but may also affect all medium-sized arteries (digestive, brain and arms/legs).

FMD can also be at the origin of Spontaneous Coronary Artery Dissection (SCAD – dissection in the artery/arteries of the heart). Finally, aortic involvement is possible, although it is more often seen in cases of focal FMD, particularly in children.

A stenosis or dissection may cause symptoms connected to a reduction in blood flow. Symptoms  depend on which artery or arteries are affected (see “symptoms” section). A ruptured aneurysm could cause internal bleeding with serious consequences. However, there are many patients with FMD who have no symptoms or signs found during medical examination. In these cases, FMD may be found on the occasion of imaging ( CT- or MR-angiography)  carried out for another reason.