“…In severe cases of encephalopathy there may be permanent clinical, psychological, or electroencephalographic abnormalities, but in these cases the diagnosis is seldom in doubt and the electroencephalographic evidence is merely confirmatory. In those milder cases where the diagnosis is doubtful the EEG, while providing very early evidence of 58 EEG DIAGNOSIS OF'DELIRIUM' developing delirium (Read, Laidlaw, Haslam, and Sherlock, 1959), may be unable to detect a latent encephalopathy.…”