Seizure Expression During Electroconvulsive Therapy: Relationships with Clinical Outcome and Cognitive Side Effects

Abstract

Since electroconvulsive therapy (ECT) can result in generalized seizures that lack efficacy, physiological markers of treatment adequacy are needed. Specific electroencephalographic (EEG) features differentiate seizures produced with barely suprathreshold right unilateral (RUL) ECT, an ineffective treatment, from effective forms of ECT. This study determined whether EEG features are sensitive to treatment condition using a broad dosing range for RUL ECT, as well as predictive of clinical and cognitive outcomes. Quantitative EEG measures and observer ratings were compared in predictive power. From a larger study, 54 in-patients with major depression were randomized to low (1.5 Â seizure threshold (ST)), moderate (2.5 Â ST), or high-dose (6 Â ST) RUL ECT, or high-dose (2.5 Â ST) bilateral (BL) ECT. High dosage RUL and BL ECT were comparable in efficacy, and superior to low and moderate dosage RUL ECT. In the slow frequency bands (d), BL ECT resulted in greater ictal power, ictal coherence, and postictal suppression than each RUL ECT condition, but the EEG measures failed to discriminate the RUL ECT groups. EEG measures were modestly associated with clinical outcome, with greater ictal power, d coherence, and postictal suppression positive predictors. None of the EEG measures were associated with cognitive outcomes. Inability to distinguish forms of RUL ECT differing markedly in dosage and efficacy suggests that EEG measures have limited potential as markers of treatment adequacy. Rather than assaying treatment adequacy, the EEG features associated with efficacy may reflect individual differences in the strength of inhibitory processes that terminate the seizure, and can help isolate the biological variability that predisposes to positive or negative clinical response to ECT.

Antidepressant-Induced Neurogenesis in the Hippocampus of Adult Nonhuman Primates

“…In contrast, ECS increases postictal seizure threshold by enhancing GABAergic tone (Nutt et al, 1981;Bowdler et al, 1983). Both the increased seizure threshold (Perera et al, 2004) and enhanced GABA activity (Sanacora et al, 2003) seen postictally with ECT correlate with positive clinical outcome in depressed patients, which is consistent with our theories that the therapeutic benefits of ECT stem from GABAergic stabilization of mood (Sackeim et al, 1983). At a cellular level, ECS may enhance GABA transmission in the hippocampus by preserving GABAergic interneurons (Dalby et al, 1996) or by changing the function of granule cells to an inhibitory GABAergic phenotype (Sloviter et al, 1996).…”

An overview on clinical aspects in magnetic seizure therapy

“…Electroencephalograms (EEGs) are obtained bilaterally with left and right frontal (Fp1 and Fp2) leads. EEG seizure duration is recorded and ictal and peri-ictal EEG parameters are used to rate (among other seizure characteristics) the postictal suppression as a marker that correlates with therapeutic efficacy (Perera et al 2004;Krystal et al 1995;Luber et al 2000).…”

Mode of action of electroconvulsive therapy: an update

“…It should be acknowledged that early research used only single channel EEG monitoring and only length as a measure of adequacy. Subsequent work at NYSPI established that this inability to define adequate cerebral seizures also pertains when more complex measures are made with multichannel recording (Perera 2004). …”