Fibromuscular Dysplasia can cause one of four changes in arteries: stenosis, aneurysm, dissection, or occlusion.
Introduction
- Fibromuscular dysplasia (FMD) is an idiopathic disease affecting small- and medium-calibre arteries.
- The disease can affect all layers of the artery, causing angiopathy.
- It typically affects the distal extracranial portion of the carotid artery.
- More common in young and middle-aged females, with a female-to-male ratio of about 3:1.
- FMD can be a cause of stroke in childhood.
Aetiology
- FMD has been found in 1% of carotid arteries during post-mortem examinations.
- It is segmental, non-inflammatory, and non-atherosclerotic.
- FMD causes both stenosis and/or dilation of blood vessels.
- Consider FMD in young patients with ischemic stroke or saccular aneurysms, with or without subarachnoid haemorrhage (SAH).
Classification
- Medial fibroplasia (80%): The most common form. Characterized by a classical beading appearance on angiography. Multiple stenotic “webs” cause arterial stenosis and poststenotic dilation. Aneurysms are often present.
- Intimal fibroplasia (10%): Involves collagen deposition within the intima and damage to the internal elastic lamina. On angiography, this appears as fibrotic band-like constriction or long tubular lesions.
- Perimedial fibroplasia (<10%): Typically seen in young girls aged 5-15 with hypertension and renal impairment.
- Medial hyperplasia (<1%): Diagnosed pathologically.
- Adventitial fibroplasia (<5%): Diagnosed with intravascular ultrasound (IVUS). Angiography resembles intimal disease.
Clinical Features
- Carotid or vertebrobasilar infarction
- Carotid or vertebral artery dissection
- Renal artery stenosis causing refractory hypertension
- Carotid stenosis with or without stroke
- Spontaneous coronary artery dissection (SCAD)
- Can affect pulmonary arteries
- Subarachnoid haemorrhage (SAH)
Investigations
- Blood Tests: FBC, U&E, and creatinine to assess renal impairment.
- Imaging: CT/MRI may show infarction or subarachnoid haemorrhage (SAH).
- Angiography (CTA/MRA/DSA): Shows narrowing and bead-like dilations of the artery, arterial dissection, or saccular aneurysms.
- Post-mortem: Vascular histology shows increased collagen within the intima and media. The media may be thinned with beading.
- No specific genetic or antemortem tests available.
Management
- Manage as per standard ischemic stroke protocol.
- Manage dissection with antiplatelets, short- or long-term as required.
- Intervention may be required for renal artery stenosis.
- Antihypertensive medications are indicated if the patient is hypertensive.
References and Recommended Reading