THE ICTAL ELECTROENCEPHALOGRAM AS A MARKER FOR THE EFFICACY OF ELECTROCONVULSIVE-THERAPY

The question of how to define a therapeutically adequate electroconvul sive therapy (ECT) has been under discussion since the early days of E CT. Although convention has asserted a demand for minimum seizure time s, the complex electrophysiological conditions involved in developing a generalized seizure make it problematic for therapeutic efficacy of ECT to be linked only with seizure duration. Within the framework of a n open clinical study of 40 patients, selected parameters of the ictal electroencephalogram (EEG) have now been examined with respect to dif ferentiation between therapeutically effective and ineffective treatme nts. For this purpose a rating scale covering both quantitative and qu alitative features of the ictal EEG was used. Although this study reco rded no correlations between seizure duration and clinical improvement , correlations were established between clinical improvement, on the o ne hand, and the frequency of epileptic discharges and their slowing d uring the spike-wave phase as well as the stereotypy of the discharge or a ''stable'' pattern of rhythmic spike-wave or sharp wave complexes , on the other. The results suggest that several of these EEG paramete rs might be combined to form a marker for therapeutically adequate ECT , and that treatment might be controlled accordingly.