Ketamine induced electroconvulsive phenomena in the human limbic and thalamic regions

Abstract

In 9 patients with cortical, limbic and thalamic electrode implants, correlative electrical activity and gross behavior were observed following administration of ketamine, 70% and N20, and thiopental. Ketamine was administered in 4 dosages: 0.5, 1, 2, and 4 mg/kg. One patient who received 0.5 mg/kg iv manifested depth electrode seizure activity without loss of consciousness. 2 patients, receiving 1 mg/kg iv, developed increased frequency in their depth electrode EEG's with transient unconsciousness. All 6 patients receiving 2 or 4 mg/kg iv developed electrical seizure activity in the limbic and thalamic areas, with uncorrelated behavioral manifestations ranging from apparent 'unconsciousness' and immobility to actual tonic and clonic motor activity. The surface EEG did not manifest the intense electrical activity in the limbic region at all times. In contrast, administration of 70% N2O and 400 mg thiopental did not induce electrical seizure phenomena. It is suggested that ketamine be used cautiously in patients with seizure disorders.