Epilepsia arithmetices revisited

Three patients whose epileptic seizures are precipitated by arithmetic calculations are reported and their clinical and EEG features analysed along with those of 7 previous cases. The seizure disorder, in general, was characterised by an onset, in adolescence, of myoclonic jerks with or without tonic-clonic seizures and generalised bisynchronous 2-5 Hz spike-and-wave discharges in the EEG. Problems involving processing of spatial information were among the tasks which induced the dysrhythmia. The specificity and the consistency of the seizure-provoking stimuli suggest that in these patients the cortical areas responsible for calculations and related functions are abnormally hyperexcitable and the repeated stimulation during cognitive activities triggers seizure discharges. Two or our patients responded well to clobazam during a follow-up period of 6 months.