๐ง Cerebral Amyloid Angiopathy (CAA) = amyloid-ฮฒ deposition in walls of small/medium cerebral vessels โ fragility โ recurrent lobar ICH.
๐ก Suspect in age >70, lobar haemorrhage, no hypertension history.
๐ Introduction
- CAA = common cause of intracerebral haemorrhage (ICH) in elderly.
- Deposition of ฮฒ-amyloid in cortical/leptomeningeal arteries Pantoni 2010.
- Different from systemic amyloidosis.
- Inflammatory variant (CAA-RI) exists and can be steroid-responsive Moussaddy 2015.
โ๏ธ Aetiology
- Deposition of amyloid-ฮฒ fibrils in vessel walls (mainly leptomeningeal & cortical arteries).
- Frequently co-exists with Alzheimerโs, but only some CAA patients develop dementia.
- ICH in CAA increases risk of later cognitive decline.
๐งฌ Genetics
- Linked to ApoE ฮต2 and ฮต4 alleles.
- Hereditary forms are rare, earlier and more severe:
- Dutch type: APP mutation (Chr 21). Lobar ICH in midlife ยฑ dementia.
- Icelandic type: Cystatin C mutation. Young adults. ICH + dementia, brainstem/cerebellar involvement.
๐ฌ 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 โ ฮฒ-amyloid in media & adventitia of small/medium arteries; Congo red +ve.
๐ฉบ Clinical Features
- Spontaneous lobar ICH: headache, seizures, focal neurology.
- Coma = poor prognosis.
- โAmyloid spellsโ (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.
๐ผ๏ธ 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.
๐งพ Boston Criteria (1990, revised)
| Category | Definition |
|---|
| Definite | Post-mortem: lobar haemorrhage + severe CAA, no other cause. |
| Probable with pathology | Lobar haemorrhage + biopsy/haematoma specimen showing amyloid, no other cause. |
| Probable | Age >60, multiple lobar bleeds on CT/MRI, no other cause. |
| Possible | Age >60, single lobar bleed, no other cause. |
๐ฉ Differentials
- Hypertensive deep bleed.
- Lobar extension from putaminal ICH.
- Haemorrhagic infarct transformation.
- AVM or haemorrhagic tumour.
- Venous sinus thrombosis.
๐ Complications
- Recurrent ICH.
- Seizures.
- Hydrocephalus (rare).
- Dementia (stepwise or progressive).
๐ Management
- โ ๏ธ 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.
๐ References
๐ก Exam Pearls:
โ Think CAA if age >70 + lobar haemorrhage + normotension.
โ MRI T2*/GRE detects microbleeds โ โpepper potโ cortex.
โ Avoid anticoagulation/antiplatelets unless absolutely necessary.
โ Inflammatory CAA variant (CAA-RI) may improve with steroids.
