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Fibromuscular Dysplasia


Learning objectives

  • To understand the pathophysiology of Fibromuscular Dysplasia
  • To understand the Causes and clinical signs and symptoms
  • To understand the Diagnostic tests for Fibromuscular Dysplasia
  • To understand the Management of Fibromuscular Dysplasia

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
FMD will do one of four things to arteries - stenosis, aneurysm, dissection, or occlusion

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

Presentations
  • Carotid or vertebrobasilar infarction
  • Carotid Dissection
  • Vertebral Dissection
  • Renal Artery Stenosis causing refractory hypertension
  • Carotid Stenosis +/- stroke
  • Spontaneous Coronary artery dissection (SCAD)
  • Can affect pulmonary arteries
  • Subarachnoid haemorrhage

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

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