What is Fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is a non-inflammatory, non-atherosclerotic vascular disease that causes abnormal cell growth in the walls of medium-sized arteries, potentially leading to narrowing, aneurysms, or dissections. While it most commonly affects the renal and carotid arteries, it can involve any artery in the body, often resulting in high blood pressure or other vascular complications.

What exactly happens in the body with Fibromuscular dysplasia?

In patients with Fibromuscular dysplasia, the arterial wall undergoes structural changes where cells grow abnormally, causing the vessel to look like a "string of beads" on imaging. This process is distinct from atherosclerosis, which is caused by plaque buildup. Because the artery wall becomes weakened or narrowed, blood flow can be restricted, or the vessel may become prone to tears (dissection) or ballooning (aneurysms). The 132 members currently in the DiseaseMaps community often report that these vascular changes lead to symptoms ranging from pulsatile tinnitus and headaches to secondary hypertension.

What are the two main types of Fibromuscular dysplasia?

Clinicians classify Fibromuscular dysplasia based on the layer of the artery wall that is most affected:

• Multifocal FMD: The most common form, characterized by the "string of beads" appearance on angiograms, typically affecting the middle layer (media) of the artery.


• Focal FMD: A less common form that appears as a singular, localized narrowing (stenosis) of the artery, which can be more challenging to diagnose.

Who is most likely to be affected by Fibromuscular dysplasia?

Data from the NIH and other clinical registries indicate that Fibromuscular dysplasia predominantly affects women, who account for approximately 90% of diagnosed cases. While the exact prevalence is difficult to determine because many cases remain asymptomatic, it is estimated to affect roughly 3 to 5 per 1,000 individuals in the general population. The condition is typically diagnosed in adults between the ages of 40 and 60, though it can be identified at any stage of life.

How does Fibromuscular dysplasia differ from other vascular conditions?

Unlike atherosclerosis, which is linked to cholesterol, smoking, and aging, Fibromuscular dysplasia is not caused by lifestyle factors or diet. A key differentiating factor is that FMD patients often have otherwise "clean" arteries without the systemic plaque buildup seen in traditional heart disease. Furthermore, the genetic component of Fibromuscular dysplasia is an active area of research; while it is not strictly hereditary in a simple Mendelian sense, there is evidence of familial clustering, suggesting a complex genetic predisposition.

Next steps

• Consult a vascular specialist or an interventional cardiologist with specific expertise in Fibromuscular dysplasia.


• Request a high-quality vascular imaging study, such as a CT or MR angiography, to screen for arterial involvement.


• Join the DiseaseMaps.org community to connect with other patients and share experiences regarding symptom management.


• Monitor your blood pressure regularly, as hypertension is the most common clinical manifestation of the disease.

Medical disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment; always seek the advice of your physician regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Fibromuscular dysplasia overview.


• Orphanet: Rare disease database for Fibromuscular dysplasia (ORPHA:3330).


• The Fibromuscular Dysplasia Society of America (FMDSA): Patient and provider resources.


• OMIM (Online Mendelian Inheritance in Man): Entry for FMD-related genetic research.