Epilepsy and neuron loss in the hippocampus

Quantitation of hippocampal neurons was performed in 20 patients with generalized epilepsy. Twelve suffered from partial seizures. The neuronal numbers were compared with the control series of patients without epilepsy. It was established that there were fewer neurons in the hippocampi from patients with epilepsy than from those of controls. The neuron loss was particularly marked in the endfolium (field H3), the granule cells (fascia dentata), and particularly in the caudal (anterior) part of the structure. Frequent, generalized epileptic seizures and long duration of the epileptic disorder influenced the neuron loss. In some parts of the pyramidal band (field H1), the neuron loss appeared at a younger age, which leads one to suspect its particular involvement in the seizure mechanism. The neuron loss was not related to the different types of seizures investigated. The results support the hypothesis of neuron loss as an ongoing process in patients with epilepsy, whatever the type of epilepsy, when tonic-clonic seizures, as is very common, are present.