= deposition of β-amyloid protein in media + adventitia of small + medium-sized vessels of cerebral cortex, subcortex and leptomeninges

Age: increasing with age: 33% in 60–70 years, 75% in >90 years

Path: fibrinoid necrosis, focal vessel wall fragmentation, microaneurysm → vessel leakage + frank hemorrhage; luminal narrowing → ischemic change

Histo: yellow-green birefringent (under polarized light) deposits along vessel wall with Congo red stain

Types: sporadic form (common), hereditary form (rare)

• asymptomatic (in many): underrecognized with petechial microhemorrhages ≤5 mm
• headaches, emesis, focal neurologic deficit, seizure, coma with macrohemorrhage >5 mm
• transient ischemic attack, dementia
• normotensive elderly without trauma
• acute / chronic intracerebral hemorrhage (ICH)
  • Cerebral amyloid angiopathy represents 2% of all ICH
    Location: cortical / subcortical in any lobe; sparing of deep white matter + basal ganglia + brainstem
• may be associated with subarachnoid / subdural hemorrhage
• leukoencephalopathy ± involvement of U-fibers
• cerebral atrophy

MR:

• multiple foci of marked signal loss at GRE imaging (most sensitive sequence for hemosiderin)

DDx: hypertensive hemorrhage (basal ganglia, thalami, brainstem)