Retrospective study of continuation electroconvulsive therapy in 50 patients

To examine patient and treatment characteristics in continuation electroconvulsive therapy (c-ECT), defined as prolonged treatment with ECT with a maximum frequency of once a week to prevent relapse.

Medical charts of 50 patients (mean age, 59 years; 74% were female) undergoing c-ECT were examined retrospectively for patient and treatment characteristics. Electrical stimulus dosage, seizure duration, and postictal suppression indices between the first and the last 4 ECT sessions were compared, and their associations with the time interval between c-ECT sessions were analyzed.

Almost all the patients (n=46; 92%) experienced recurrent medication-resistant mood disorders. During a median c-ECT period of 393 days (interquartile rate, 211-677 days), the frequency of c-ECT ranged from once a week (n=15; 30%) to once every 4 to 6 weeks (n=17; 34%), and ECT was administered almost exclusively bifrontotemporally (n=46, 92%). The mean (SD) time interval between consecutive c-ECT sessions was 19 (11) days. The number of days between c-ECT sessions correlated positively with median seizure duration (motor activity: r=0.390, P=0.005; electroencephalographic activity: r=0.351, P=0.013).

In 50 patients with long-standing, recurrent, medication-resistant mood disorders who were treated with c-ECT, increased time interval between consecutive c-ECT sessions was correlated with increased seizure duration. Whether bifrontotemporal c-ECT requires a lower frequency to sustain remission compared with unilateral c-ECT needs further investigation.