Gradually progressive dementia without discrete cerebrovascular events in a patient with Sneddon's syndrome.

A 37-year-old man sought medical advice because of an 8-year history of a slowly progressive dementing illness with no clinically apparent discrete strokelike episodes. Cognitive functioning was markedly, globally impaired without lateralizing or localizing features. Widespread livedo reticularis led to a diagnosis of Sneddon's syndrome. Antiphospholipid antibodies and lupus anticoagulant were negative. Magnetic resonance imaging showed widespread cerebral atrophy, cortical and subcortical cerebral infarcts, and extensive periventricular white matter abnormalities. Cerebral angiography revealed diffuse medium- and small-vessel occlusive disease, with numerous collaterals in the mid and distal circulation but no evidence of atherosclerosis or vasculitis. No other cause of a dementing illness was found. We postulate that our patient's dementia was due to the cumulative effects of multiple cerebral infarcts.