What is the vascular condition that leads to multiple aneurysms called Fibromuscular Dysplasia (FMD)

From the Guidelines

Fibromuscular dysplasia (FMD) is the vascular condition that leads to multiple aneurysms, characterized by a nonatherosclerotic, noninflammatory vascular disease with either focal stenosis or multiple constrictions due to thickening of a layer of the arterial wall. This condition is more commonly encountered in middle-aged women and can affect any portion of the cervical or intracranial arteries, most frequently involving the internal carotid arteries bilaterally 1. The disease can cause a range of symptoms depending on the location and extent of arterial obstruction, including stroke, transient ischemic attack (TIA), carotid dissection, Horner syndrome, cranial nerve palsies, and subarachnoid hemorrhage.

Some key characteristics of FMD include:

• A "string of beads" appearance on imaging studies due to segments of narrowing alternating with dilated sections
• Affecting medium-sized arteries, most commonly the renal and carotid arteries
• More prevalent in women, particularly those between 30-50 years of age
• Symptoms vary depending on which arteries are affected and may include high blood pressure, headaches, pulsatile tinnitus, stroke, or kidney dysfunction
• Treatment typically involves managing symptoms and complications, with options including antihypertensive medications, antiplatelet therapy, and in some cases, procedures like angioplasty to improve blood flow 1.

It is essential to note that the pathophysiology and natural history of FMD are unknown, and the relationship of FMD to carotid arterial dissection is poorly understood 1. However, spontaneous dissection and aneurysmal degeneration are additional causes of symptomatic events in patients with carotid FMD. Regular monitoring with vascular imaging is crucial for patients with FMD to detect aneurysms or dissections early, as recommended by the 2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS guideline on the management of patients with extracranial carotid and vertebral artery disease 1.

From the Research

Vascular Condition Leading to Multiple Aneurysms

The vascular condition that leads to multiple aneurysms is called Fibromuscular Dysplasia (FMD) 2, 3, 4, 5, 6.

Characteristics of FMD

• FMD is a non-atherosclerotic vascular disease that may involve medium-sized muscular arteries throughout the body 2, 6.
• The majority of FMD patients are women, but men may have a more progressive disease, especially when smoking 2.
• FMD can lead to arterial aneurysms, dissections, and tortuosity, in addition to the classical phenotype of string of beads or focal stenosis 2, 3, 4, 6.
• The disease can involve most arteries throughout the body, resulting in a variety of clinical symptoms 2, 6.

Clinical Manifestations of FMD

• Arterial hypertension and neurological symptoms are the most frequent clinical presentations, as renal and cerebrovascular arteries are the most commonly involved 2.
• Men and African Americans with FMD are more likely to have traditional atherosclerotic risk factors and vascular manifestations, compared with women and Caucasians 5.
• Men with FMD are more likely to have dissection of aorta and renal artery as well as aneurysm of vertebral artery, coronary artery, aorta, and iliac artery 5.

Diagnosis and Management of FMD

• Diagnosis is based on CT-, MR-, or conventional catheter-based angiography during work-up of clinical manifestations 2.
• The management of FMD depends on the vascular phenotype as well as the clinical picture 2.
• Ongoing FMD-related research aims to improve our understanding of the disease's clinical manifestations, natural history, epidemiology, and genetics, and to develop novel imaging modalities and blood-based biomarkers for diagnosis and management 6.