Temporal lobe epilepsy caused by domoic acid intoxication: evidence for glutamate receptor-mediated excitotoxicity in humans.

We describe the development of temporal lobe epilepsy in an 84-year-old man who had suffered domoic acid intoxication. Following intoxication he had nausea, vomiting, confusion, and coma. Generalized convulsions and complex partial status epilepticus progressively developed. After 3 weeks he improved and was seizure free with severe residual memory deficit. Electroencephalograms initially showed periodic epileptiform discharges, later evolving to epileptic abnormalities over frontotemporal regions with diffuse slow waves. Eight months after the intoxication the electroencephalogram was normal. One year after the acute episode, complex partial seizures developed. Electroencephalograms showed epileptic discharges independently over both temporal lobes, with left-sided predominance. Magnetic resonance imaging revealed a hyperintense T2-weighted signal and atrophy of both hippocampi; a positron emission tomographic scan showed bitemporal decreased glucose metabolism. Pneumonia developed and the patient died 3 1/4 years after the intoxication. Autopsy disclosed severe bilateral hippocampal sclerosis. The seizures following acute domoic acid intoxication, the postmortem pathology, and the fact that temporal lobe epilepsy developed 1 year after intoxication indicate that the human hippocampus is also vulnerable to kainate receptor excitotoxicity, and provide strong evidence supporting the role of excitotoxic injury in epileptogenesis. This report provides a unique human parallel to, and validates the animal model of, kainate-induced epilepsy as an important tool for studying temporal lobe epilepsy.