Idiopathic or primary angiitis of the CNS (PACNS) and cerebral amyloid angiopa thy (CAA) are unusual vasculopathies generally regarded as unrelated disorders. A few case reports have,however, described granulomatous angiitis in patients wi th sporadic,amyloid βpeptide (Aβ)-related CAA. Here we describe the clinical, neuroradiological and neuropathological features of nine patients with Aβ-rel ated angiitis (ABRA). Combining these with the individual case reports drawn fro m the literature has allowed us to define ABRA as a clinical entity and to compa re its features with those of PACNS. The mean age of presentation of ABRA (67 ye ars) is higher than that of PACNS but lower than that of sporadic non-inflammat ory Aβ-related CAA.Alterations in mental status (59%), headaches (35%), seiz ures and focal neurological deficits (24%) are common. Hallucinations are a pre senting manifestation in 12 %of cases. Most patients have white matter hyperint ensities on MRI but these are of similar appearance to those in PACNS. Cerebrosp inal fluid usually shows modest elevation of protein and pleocytosis.Neuropathol ogy reveals angiodestructive inflammation,often granulomatous, and meningeal lym phocytosis. Aβis consistently present in abundance in affected blood vessels bu t usually scanty within the parenchyma of the cerebral cortex.However, the corte x includes numerous activated microglia,occasionally in a plaque-like distribut ion and containing cytoplasmic Aβ. The cerebral white matter shows patchy glios is and rarefaction, in some cases marked. Our findings (i) help to dissect one s eparate clinicopathological entity from what is likely to be a spectrum of prima ry angiitides of the CNS;(ii) have important therapeutic implications for one ca tegory of patients with amyloid-related vasculopathy; and (iii) may provide val uable insights into the development of amyloid-associated inflammation, of rele vance not only to ABRA but also to Aβ-immunization-related encephalitis and t o Alzheimer’s disease.
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