Changes in plasma catecholamines after tonic-clonic seizures.

Concentrations of circulating catecholamines increase after induced seizures in animals and electroconvulsive therapy in humans. We measured plasma epinephrine and norepinephrine concentrations after a single spontaneous tonic-clonic convulsion in 17 patients to determine whether similar changes occur and to determine their magnitude. Plasma epinephrine and norepinephrine rose sharply within 30 minutes of the seizure and then declined rapidly. The norepinephrine response was attributed to generalized sympathetic neural activation and was sufficient to exert a direct vasoconstrictor effect. The epinephrine response was presumably due to adrenal activation and was large-enough to have cardiovascular or metabolic consequences.