Significance and management of transitory cognitive impairment due to subclinical EEG discharges in children.

Epileptiform EEG discharges not accompanied by obvious clinical events are generally regarded as subclinical or interictal. However, in many patients suitably sensitive methods of continuous psychological testing demonstrate brief episodes of impaired cognitive function during such discharges. This phenomenon of transitory cognitive impairment (TCI) is found in some 50% of those patients who exhibit discharges during testing. With focal discharges, the effects are material specific, the deficit being demonstrable only with tasks involving that hemisphere in which the discharge occurs. It is probable that TCI contributes to the known cognitive problems of many people with epilepsy, and indeed causes deficits which are not readily recognised. Thus TCI may be found in benign epilepsy of childhood, a condition believed specifically not to be associated with psychological problems. An important practical issue is whether TCI materially impairs day to day psychosocial function and if so whether drug treatment is either desirable or effective. A preliminary controlled trial of antiepileptic treatment of TCI is described: suppression of discharges was associated with significant improvement in psychosocial function.