The central nervous system electrical potentials recorded by the EEG are sensitive to alterations in the levels of consciousness and attention (Mesulam, 1986). Thus it is understandable that previous studies on delirious patients using routine EEGs have shown an increase of slow-wave activity and slowing and disruption of the normal alpha rhythm (Romano & Engel, 1944). At present, the electrocephalogram is widely accepted as a valuable ancillary laboratory procedure for diagnosis and serial evaluation of delirium, as EEG changes often accompany delirium.