Overview

Fibromuscular dysplasia (FMD) is a rare condition which involves the abnormal formation of cells in the arteries, which leads to the narrowing of the vessels, which in turn reduces the blood flow to the organs. The commonly affected organs are the brain and the kidneys. It primarily affects women and can occur at any age. 

This condition usually has no symptoms, but symptoms may vary depending on the location. Common symptoms include hypertension, headache, ringing in the ear, dizziness, neck pain and stroke. Diagnosis involves different screening tests such as CT scans, ultrasound, and angiography. Treatment focuses on managing symptoms through medication or surgical interventions. Early detection and regular monitoring are important for preventing complications and improving health outcomes.

Understanding fibromuscular dysplasia

What are the types of fibromuscular dysplasia?

Fibromuscular Dysplasia (FMD) has two main types, identified by how the arteries look during tests:

• Multifocal FMD: This is the most common type. The arteries appear like a "string of beads," with alternate wide and narrow sections
• Focal FMD: This type is much less common. It involves localised areas of arterial narrowing or lesions on the arterial walls, where a lesion refers to an area of abnormal tissue

What are the commonly affected arteries?

Fibromuscular Dysplasia (FMD) can cause blood vessels to narrow, bulge, or develop a beaded appearance. It can affect various arteries, including:

• Carotid arteries: Located in your neck, connecting your heart and brain
• Renal arteries: Carrying blood from your heart to your kidneys
• Coronary arteries: Supply blood to your heart
• Mesenteric arteries: Deliver blood to your intestines
• Other arteries: These include those that travel to your legs, arms, and other parts of your body

Who is affected by fibromuscular dysplasia?

Fibromuscular Dysplasia (FMD) predominantly affects females under the age of 50. Most studies show that it has a female-to-male ratio of 3:1.¹ However, it can also occur in babies, children, men, and the elderly.² The average age for FMD diagnosis is 48 years.¹

Risk factors

The cause of fibromuscular dysplasia (FMD) is still unclear, though research suggests both genetic and environmental factors may play a role. FMD is reported in identical twins, indicating a possibility of a genetic component. Some studies have found a small percentage of family history and associations with certain genes. Environmental factors such as smoking are more common among FMD patients, and mechanical factors such as the way the kidneys are positioned inside the body could also play a role. Although FMD is more common in women, the role of oestrogen is uncertain. Despite these findings, the exact cause of FMD remains unknown.¹

What are the symptoms of FMD?

Patients with Fibromuscular Dysplasia (FMD) may experience various symptoms depending on which arteries are affected. However, many patients do not have any symptoms and are diagnosed incidentally when an imaging test of the arteries is conducted for unrelated reasons.

Some commonly affected arteries have the following symptoms

Renal (kidney) arteries

• High blood pressure
• Whooshing sound in the abdomen or sides
• Renal artery aneurysm, known as bulging and weakening of the artery
• Tear in the artery of the kidney

Cerebrovascular (brain and neck) arteries

• Headaches (often migraines)
• Ringing in the ears
• Stroke 
• Neck pain
• Dizziness
• Brain aneurysm

Other affected areas

• Abdominal pain after eating
• Weight loss
• Arm or leg pain with activity (upper or lower extremity FMD)³

What are the diagnostic tests for FMD?

All patients suspected of having Fibromuscular Dysplasia (FMD) should have a detailed physical examination and medical history. However, a definitive diagnosis of FMD requires screening tests.³

Screening techniques

There are different types of screening tests to diagnose FMD.

Duplex ultrasound

This is the first screening test for FMD. It can show signs like turbulence, twisting, and increased blood flow speeds in the arteries, which suggest FMD. Some limitations affect the accuracy of the test. It can be affected by factors such as obesity, kidney movement during breathing, and bowel gas.

Computed tomography angiography (CTA)

This is a very effective, non-invasive test for diagnosing FMD. It provides clear, detailed pictures and can show the classic "string-of-beads" appearance in the arteries. It can also detect kidney aneurysms and areas of tissue damage.

Magnetic resonance angiography (MRA)

This test has similar accuracy to CTA but doesn’t involve radiation or contrast dye that can harm the kidneys. However, it’s not suitable for patients with severe kidney failure. Studies have shown that MRA is very reliable for detecting FMD.

Arteriography

This is the most accurate test for diagnosing FMD. It can also measure blood pressure differences across narrowed arteries, which helps determine how significant the narrowing is.

This test allows for immediate treatment, such as angioplasty, if needed. New techniques like intravascular ultrasound can improve the evaluation of artery conditions and help monitor for re-narrowing after treatment.¹

What are the treatment options for FMD?

There is no cure for fibromuscular dysplasia (FMD), so treatment focuses mainly on careful monitoring, lifestyle changes, and managing symptoms. Some patients may need procedures like angioplasty or treatment for aneurysms. The treatment plan for patients with Fibromuscular Dysplasia (FMD) depends on where the disease is located and what symptoms are present, but there are no clear treatment guidelines due to limited research. 

Medical management 

Antiplatelet therapy was more frequently used in older patients, those with a history of coronary artery disease or previous vascular interventions for FMD, and those with cerebrovascular FMD. These patients were given antiplatelet medications, which is a common practice to prevent blood clots. Managing blood pressure is also crucial for FMD patients who have hypertension. For those with kidney artery involvement, using an angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) has been recommended.⁴

Surgical management

Patients with cerebral, visceral, or arterial aneurysms who don't have symptoms may still need treatment such as surgery. The decision to treat and the method (such as coiling, stenting, or open surgery) depend on factors like the size and location of the aneurysm, the patient's risk of rupture (like having high blood pressure or a family history of aneurysms), and whether a less invasive endovascular repair is possible.⁴

Importance of early detection

By being aware of the signs and seeking early detection, individuals at risk for FMD can achieve better health outcomes and reduce the likelihood of severe complications

Prevents complications

Early detection of Fibromuscular Dysplasia (FMD) can help prevent serious complications such as high blood pressure, stroke, or aneurysms.

Improves management

Identifying FMD early allows for better management of symptoms and monitoring of disease progression.

Support and awareness

Joining advocacy organisations and support groups can connect you with others who have FMD, helping raise awareness and funds for research.

Education and immediate attention

Your healthcare provider will educate you about the signs and symptoms that need immediate medical attention, which vary depending on the affected arteries.

Stroke awareness

People with FMD should know the signs of a stroke, which include sudden:

• Numbness on one side of the body
• Confusion, trouble speaking, or difficulty understanding speech
• Vision problems in one or both eyes
• Dizziness or imbalance  
• Severe headache with no known cause

Conclusion

FMD is a rare condition that affects arteries and can present differently depending on age, often causing high blood pressure and sometimes strokes. Management requires a team approach.. 

FMD can appear in different forms, such as the "string-of-beads" pattern in arteries, aneurysms, and artery tears. After diagnosis, patients may need angioplasty, and long-term follow-up is crucial due to the risk of recurrence. Patients without symptoms are typically managed with antiplatelet drugs and antihypertensive medications. Regular monitoring is important. Clear communication of the management plan by the healthcare team helps prevent complications and ensures effective management of FMD. These findings highlight the need for thorough screening tests and early detection to prevent serious complications and improve patient outcomes.

FAQs

Is there any cure for FMD?

There is no cure for Fibromuscular Dysplasia. Treatment mainly aims to relieve symptoms and prevent complications.

Can I prevent FMD?

Since the causes of FMD are not yet understood, there are no known strategies to prevent it.

How do you take care of yourself if you are diagnosed with FMD?

If you have Fibromuscular Dysplasia (FMD), managing your health involves a few key steps. Regularly check your blood pressure and avoid smoking. Make sure to attend all follow-up appointments and adhere to your prescribed medications. Getting involved in support groups can also be beneficial, as they provide connections with others who have FMD and help raise awareness and funds for research.