The Electroencephalographic Pattern during Electroconvulsive Therapy IV. Spectral Energy Distributions with Methohexital,Innovar and Ketamine Anesthesias

During Phase III of nondominant unilateral ECT seizures, total energy, total peak energy, total delta energy, and 1/2-power duration of total delta energy are all less (shorter) in the unstimulated, dominant hemisphere than they are in the stimulated hemisphere. Interhemi-spheric differences in total energy are greatest in the lateral frontotemporal cortex, where they average 40 percent with both methohexital and ketamine anesthesias in F₈ > F₇ and T₄ > T₃. This circumstance probably explains the characteristic memory sparing associated with nondominant unilateral ECT.

The magnitudes of total and peak energies in each frequency band decrease in the order: delta > theta > alpha > beta. Delta energy constitutes approximately three-fourths of the unilateral ECT seizure's total energy, and Phase III delta energy may be the therapeutically effective agent in this treatment. Seizures induced during ketamine anesthesia are associated with a higher percentage of delta energy, with higher magnitudes of total energy and of total and peak delta energy, and with longer 1/2-power durations of delta energy. Nondominant unilateral ECT with ketamine anesthesia offers promise as the treatment of choice for patients resistant to ECT administered with methohexital anesthesia.