Neuropsychiatric sequelae after cardiac arrest or anaesthesia are infrequently reported. A review of the literature is given by Blackwood et al. (1963). Fletcher (1945) described permanent but comparatively mild effects which were attributed to nitrous oxide rather than to circulatory disturbances. Bedford (1955) described 18 cases of extreme dementia following general anaesthesia in geriatric patients who were quite well mentally before their operations. He indicated the diagnostic pitfalls involved in attributing minor psychiatric disabilities to the anaesthetic. Neuburger (1954) described diffuse cerebral damage combined with Wernicke-like lesions in the mamillary bodies in 2 patients. Brierley (1961) described the pathological changes in the brain of a 2-year-old child, who died 1 month after a cardiac arrest of 10–15 minutes. There were lesions in the mamillary bodies and inferior colliculi resembling those seen in Wernicke's encephalopathy. However, Brierley and Cooper (1962) later described a 43-year-old woman, whose blood pressure fell to unrecordable levels for 3 minutes and who became severely demented, developed Parkinsonism and had a Korsakoff type learning defect. She survived for 23 months. The brain showed most damage in the occipital cortex and thalamus, and less in the midbrain. Unfortunately the mamillary bodies were not identifiable.