Fibromuscular Dysplasia

Learning objectives

Introduction

• Fibromuscular dysplasia (FMD) is an idiopathic disease of small- and medium-calibre arteries.
• The disease can affect all the layers of the artery causing an angiopathy.
• It tends to affect the distal extracranial portion of the carotid artery.
• Commoner in young and middle aged females. Female > male incidence is about 3:1.
• It can be a cause of stroke in childhood

Aetiology

• Has been found in 1% of carotid arteries at post mortem.
• It is segmentary, non-inflammatory and non-atherosclerotic
• Causes both stenosis and/or dilation of blood vessels.
• Consider diagnosis in young patients with ischaemic stroke or with saccular aneurysms +/- SAH.

Classification

• Medial fibroplasia (80%): Commonest form. Classical beading appeanace on angiogrpahy. The multiple stenotic “webs” cause arterial stenosis and poststenotic dilation. Aneurysms are often seen.
• Intimal fibroplasia (10%): Collagen deposition within the intima with damage to internal elastic lamina. Angiography a fibrotic band-like constriction or long tubular lesions
• Perimedial fibroplasia(<10%): Young girls aged 5-15 with hypertension and renal impairment
• Medial hyperplasia (<1%): Pathologic diagnosis.
• Adventitial fibroplasia (< 5%)Can be diagnsoed using intravascular ultrasound (IVUS) imaging. Angiography resembles intimal disease.

Clinical

Investigations

• FBC, U&E, Creatinine: look for renal impairment
• CT/MRI may show infarction or SAH
• CTA/MRA/DSA : Narrowing and bead-like dilatations of artery seen on Angiography. Arterial dissection. Coexistence of saccular aneurysms
• Post mortem: vascular histology shows increased collagen within the intima and media. The media may be thinned and there may be beading.
• No specific genetic or antemortem tests

Management

• As per normal Ischaemic stroke.
• Manage dissection usually with antiplatelets short/long term.
• Intervention for Renal artery stenosis may be useful.
• Antihypertensive medications if hypertensive

References and recommended reading

• Beleglman et al. Fibromuscular dysplasia. Current Opinion in Rheumatology 2000, 12:41-47
• Spontaneous Coronary artery dissection (SCAD) Review
• Fibromuscular dysplasia: what the radiologist should know: a pictorial review. Insights Imaging. 2015 Jun; 6(3): 295-307.
• Fibromuscular dysplasia and childhood stroke. Brain 2013: 136; 1846-1856

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