EEG source localization during postictal delirium following electroconvulsive therapy

Delirium is a highly prevalent syndrome with short-time disturbances of consciousness, cognition, and brain electrical activity. The aims of this study were (1) to investigate a possible relation between the neuropsychological features and the topographic frequency distribution of brain electrical activity during delirium as evoked by electroconvulsive therapy (ECT) and (2) to estimate the respective cortical generator of brain electrical activity with Low Resolution Brain Electromagnetic Tomography (LORETA, Ref. 1). 12 patients with major depression have been investigated during ECT course. EEG data were Fourier transformed and correlated with neuropsychological data. Changes of theta activity at Fz showed correlations with changes of awareness of the surrounding (r=0.59; p<0.05) and of retrieval from episodic memory (r=-0.71; p<0.05). Source analysis revealed a slow-wave focus in anterior cingulate cortex (ACC; BA 24; t-test: p<0.05). The results indicate a relation between this ACC focus and the core features of delirium which is consistent with neuropsychological theories about attentional and executive functions of ACC.

1 Pascual-Marqui et al. 1994. Int J Psychophysiol 148: 49–65