FMD is a noninflammatory, nonatherosclerotic arterial disease that most commonly affects the renal and internal carotid arteries (ICAs) but has been observed in almost every artery in the body. It is characterized by smooth muscle cell and fibrous tissue overgrowth in one or more layers of the renal arterial wall.
The renal arteries compromise 65% to 75% of cases of FMD, occurring bilaterally in 35% of cases. The carotid and vertebral arteries are involved in 25% to 30% of cases. Multivessel involvement is common.
FMD occurs most frequently in women aged between 20 and
60 years, but may also be seen in men, older individuals, and in the pediatric population.1,2 It is estimated to affect anywhere between 5.8 and 8.6 million women in the United States.
Hypertension, headache, and pulsatile tinnitus are the most common presenting manifestations. Other signs and symptoms include dizziness, cervical and abdominal bruits, neck pain, flank or abdominal pain, nonpulsatile tinnitus, transient ischemic attack (TIA), and stroke. The clinical presentation is dictated by the affected arteries.
FMD can be asymptomatic and incidentally identified on an imaging study performed for a different clinical indication. In addition to arterial stenosis, patients with FMD can present with aneurysms and dissections. A history of FMD in first- or second-degree relatives is rare and occurs in around 7% of patients.