Makindo Medical Notes

⚠️ Fibromuscular Dysplasia (FMD) can cause four vascular changes: stenosis, aneurysm, dissection, or occlusion. Always consider in young stroke patients or those with refractory hypertension.

🧠 Introduction

• FMD is an idiopathic, non-inflammatory, and non-atherosclerotic disease of small- and medium-sized arteries.
• It leads to segmental arterial abnormalities affecting flow and structure.
• Most often affects the renal arteries and distal extracranial carotid arteries, but may involve multiple vascular beds.
• More common in young and middle-aged females (female:male ≈ 3:1).
• Accounts for a proportion of childhood strokes and young-onset renovascular hypertension.

🔍 Aetiology

• Found in ≈1% of carotid arteries at post-mortem studies.
• Segmental in nature: alternating areas of stenosis and dilation.
• Does not arise from atherosclerosis or vasculitis.
• Consider in ischaemic stroke or saccular aneurysms (with or without subarachnoid haemorrhage).

📑 Classification

• 💢 Medial fibroplasia (≈80%) – Most common. Classic “string-of-beads” appearance on angiography. Multiple webs → stenosis with post-stenotic dilatation. Aneurysms frequent.
• 🧱 Intimal fibroplasia (≈10%) – Collagen deposition in intima. Appears as long tubular stenosis or concentric band-like narrowing.
• 👧 Perimedial fibroplasia (<10%) – Seen in young girls (5–15 years). Often presents with hypertension and renal dysfunction.
• 🔬 Medial hyperplasia (<1%) – Only confirmed pathologically.
• 🧩 Adventitial fibroplasia (<5%) – Seen on intravascular ultrasound (IVUS); angiography mimics intimal disease.

💡 Clinical Features

• Stroke or TIA due to carotid/vertebrobasilar infarction.
• Carotid/vertebral dissection causing headache, neck pain, or stroke.
• Renal artery stenosis → refractory hypertension.
• Carotid stenosis (with or without stroke).
• Spontaneous coronary artery dissection (SCAD) (link).
• Rare: pulmonary artery involvement.
• May present with subarachnoid haemorrhage from aneurysm rupture.

🧪 Investigations

• Bloods: FBC, U&E, creatinine (renal function).
• CT/MRI Brain: To detect infarction or SAH.
• Angiography (CTA / MRA / DSA): Shows stenosis with “string-of-beads”, dissections, or aneurysms.
• Histology (post-mortem/biopsy): Collagen deposition in intima/media, thinned media with beading.
• No validated genetic/ante-mortem biomarkers currently available.

🩺 Management

• 🚑 Ischaemic stroke: Follow standard stroke protocols (antiplatelets, BP control).
• 🩹 Dissections: Managed with antiplatelets short/long term.
• 🩻 Renal artery stenosis: May require percutaneous intervention or surgery.
• 💊 Hypertension: Treat with antihypertensive drugs.
• 🔁 Long-term follow-up with vascular imaging as disease can recur or progress.

📚 References & Further Reading

• Beleglman et al. Fibromuscular dysplasia. Curr Opin Rheumatol 2000
• Spontaneous Coronary Artery Dissection (SCAD) Review
• Radiological Guide to Fibromuscular Dysplasia
• Childhood Stroke & FMD Review