Absence status in adults.

Twelve cases of adult absence status were seen over 7 years. Clinically the disorder was characterised by long periods of clouding of consciousness with myoclonic phenomena of varying degrees of severity. The EEGs showed sustained spike-wave, polyspike and rhythmic slow activity. In one exceptional patient bizarre hemitonic seizures were documented clinically and on EEG. Diagnosis of the condition was frequently delayed and the histories of most patients showed episodes of obscure confusional behaviour, undiagnosed over the previous months or years. Psychiatric disturbances of various types were surprisingly common, contributing to diagnostic difficulty. Treatment with conventional anticonvulsants was often disappointing. In contrast, sodium valproate and clonazepam were found to be very effective.