Makindo Medical Notes

🧠 Cerebral Amyloid Angiopathy (CAA) = amyloid-β deposition in walls of small/medium cerebral vessels → fragility → recurrent lobar ICH. 💡 Suspect in age >70, lobar haemorrhage, no hypertension history.

📖 Introduction

• CAA = common cause of intracerebral haemorrhage (ICH) in elderly.
• Deposition of β-amyloid in cortical/leptomeningeal arteries Pantoni 2010.
• Different from systemic amyloidosis.
• Inflammatory variant (CAA-RI) exists and can be steroid-responsive Moussaddy 2015.

⚙️ Aetiology

• Deposition of amyloid-β fibrils in vessel walls (mainly leptomeningeal & cortical arteries).
• Frequently co-exists with Alzheimer’s, but only some CAA patients develop dementia.
• ICH in CAA increases risk of later cognitive decline.

🧬 Genetics

• Linked to ApoE ε2 and ε4 alleles.
• Hereditary forms are rare, earlier and more severe:
  • Dutch type: APP mutation (Chr 21). Lobar ICH in midlife ± dementia.
  • Icelandic type: Cystatin C mutation. Young adults. ICH + dementia, brainstem/cerebellar involvement.

🔬 Pathology

• CAA is a leading cause of lobar haemorrhage in older patients.
• Lobar bleeds (temporal/occipital > frontal/parietal). Contrast: hypertensive bleeds = deep (putamen, thalamus, pons).
• Microscopy → β-amyloid in media & adventitia of small/medium arteries; Congo red +ve.

🩺 Clinical Features

• Spontaneous lobar ICH: headache, seizures, focal neurology.
• Coma = poor prognosis.
• “Amyloid spells” (TIA-like focal deficits due to small bleeds/SAH).
• Recurrent micro/macrobleeds, sometimes provoked by mild trauma, thrombolysis or antithrombotics.
• Progressive cognitive decline if multiple bleeds.

🖼️ Investigations & Imaging

• CT: Acute lobar haemorrhage, often cortical/subcortical. May recur in different lobes. Deep nuclei usually spared.
• MRI T2*/GRE/SWI: Detects old bleeds (haemosiderin). Microbleeds <10 mm = round, low-signal foci.
• CAA-RI: Dramatic oedema on T2 MRI, often steroid-responsive.
• CTA/MRA/CTV: If alternative vascular causes suspected.
• PET: Research tool only.
• Genetics: ApoE typing in research; APP/Cystatin C in suspected familial cases.
• Histology: Congo red staining of biopsy/post-mortem brain confirms amyloid.

🧾 Boston Criteria (1990, revised)

🚩 Differentials

• Hypertensive deep bleed.
• Lobar extension from putaminal ICH.
• Haemorrhagic infarct transformation.
• AVM or haemorrhagic tumour.
• Venous sinus thrombosis.

📉 Complications

• Recurrent ICH.
• Seizures.
• Hydrocephalus (rare).
• Dementia (stepwise or progressive).

💊 Management

• ⚠️ Avoid antiplatelets, anticoagulants, thrombolysis if possible.
• Standard haemorrhagic stroke care (BP, ICP, seizure control).
• Falls prevention (reduce trauma risk).
• Surgery for life-threatening bleeds in selected cases.
• Long-term care: dementia management, seizure prophylaxis, vascular risk reduction.

📚 References

• Knudsen KA, Rosand J, Karluk D. Clinical diagnosis of CAA: Boston criteria. Neurology. 2001;56(4):537–9.
• CAA Systematic Review. J Clin Neurol 2011;7:1–9
• Radiopaedia – CAA Imaging

💡 Exam Pearls:
– Think CAA if age >70 + lobar haemorrhage + normotension.
– MRI T2*/GRE detects microbleeds → “pepper pot” cortex.
– Avoid anticoagulation/antiplatelets unless absolutely necessary.
– Inflammatory CAA variant (CAA-RI) may improve with steroids.