Makindo Medical Notes

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 ischaemic 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 ischaemic 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

• Beleglman et al. Fibromuscular dysplasia. Current Opinion in Rheumatology 2000
• Spontaneous Coronary artery dissection (SCAD) Review
• Fibromuscular Dysplasia: What the Radiologist Should Know
• Fibromuscular Dysplasia and Childhood Stroke: A Review