Transient psychosis in a girl with epilepsy and continuous spikes and waves during slow sleep (CSWS).

A normally developed and healthy 6-year-old girl suffered the onset of epilepsy with generalized tonic-clonic seizures and atypical absences. Initially the EEG showed epileptiform activity over the temporal and parietal regions, later there were episodes of bilateral synchronous spike-wave activity with a frequency of 1.5-2.5 Hz. After a few months, deterioration of cognitive and behavioural functions appeared and gradually increased with the development of a full-blown disintegrative psychosis that went on for several months. Sleep EEG recordings showed the characteristic abnormality described as continuous spikes and waves during slow sleep. Later there was a remarkable improvement of neuropsychiatric functions but a second outbreak of psychosis seems to have left the girl, who is now 9 years of age, with severe mental impairment.