Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory disease of the blood vessels that causes abnormal growth within the wall of an artery.
[3] Symptoms of craniocervical involvement include headaches (mostly migraine), pulsatile tinnitus, dizziness, and neck pain, although patients are often asymptomatic.
On physical examination, one may detect neurological symptoms secondary to a stroke or transient ischemic attack (TIA), a bruit over an affected artery, and diminished distal pulses.
[1] If the lower limb arteries are affected, the patient may present with cold legs or evidence of distal embolic disease.
FMD present in the subclavian artery may cause arm weakness, paresthesia, claudication, and subclavial steal syndrome.
This syndrome may be suspected in patients with multiple aneurysms and/or tears (dissections) in arteries, in addition to the typical angiographic findings of FMD.
[9] While the cause of FMD remains unclear, current theory suggests that there may be a genetic predisposition as case reports have identified clusters of the disease and prevalence among twins.
[7] According to Cleveland Clinic, approximately 10% of cases appear to be inherited and FMD often coexists with other genetic abnormalities that affect the blood vessels.
FMD has been pathologically categorized into three types of classifications: multi-focal, focal, and adventitial, each referring to the particular layer of arterial wall being affected.
[4] "The 'bead' component is often larger than the normal arterial lumen, and in a subset of patients with FMD, aneurysms are present that may require treatment.
This form is considered rare, but angiographic appearance may look similar to the focal subtype of FMD, making the distinction difficult.
[citation needed] It is the lack of specific symptoms and their potential to appear anywhere that makes FMD a challenge to detect early on.
According to the Michigan Cardiovascular Outcomes Research and Reporting Program (MCORRP, 2013) the length of time from a patient's first signs or symptoms to diagnosis is commonly 5 years.
[4] Invasive testing through angiography is considered the best way to detect FMD, though it is typically not done early in the diagnosis process due to the higher risk of complications.
Occasionally, FMD is diagnosed asymptomatically after an unrelated x-ray presents the classic "string of beads" appearance of the arteries, or when a practitioner investigates an unexpected bruit found during an exam.
Catheter-based angiography (with contrast) is the most accurate imaging technique; this test involves a catheter inserted into a large artery and advanced until it reaches the examined vessel.
According to a study published in the Journal of Vascular Surgery, "catheter-based angiography is the only imaging modality that can accurately identify the changes of FMD, aneurysm formation, and dissection in the branch vessels.
Many studies have assessed the success rate of percutaneous transluminal angioplasty (PTA) in these cases, and have found relief of hypertensive symptoms.
[citation needed] In pediatric cases, treatment is determined by factors such as age and disease location but it routinely involves controlling hypertension, re-establishing vascular flow, preventing clots, and improving lifestyle through diet, exercise, and smoking cessation.
According to an article published in Cath Lab Digest, "effective PTRAs result in cured or controlled blood pressure, which is often signified by reductions in plasma renin activity and angiotensin II levels, and when compared with surgery, percutaneous balloon angioplasty is less costly, able to be performed on an outpatient basis, results in lower morbidity, and the use of stenting is not primarily necessary.
In some cases, if not managed properly, FMD-related aneurysms can occur and cause bleeding into the brain, resulting in a stroke, permanent nerve damage, or death.