HIPPOCAMPAL SYNAPTIC PATHOLOGY IN PATIENTS WITH TEMPORAL-LOBE EPILEPSY

Immunostaining of synaptic terminals was studied in the hippocampus of 26 patients who had surgical resections for intractable temporal lobe epilepsy. Two monoclonal antibodies (EP10 and SP12) reactive with dis tinct synaptic antigens were used on paraffin-embedded tissues. The re sults indicated qualitative reductions on synaptic terminals in CA4 an d other regions where cell loss is reported. The inner molecular layer of the dentate gyrus was observed to have increased synaptic immunost aining. Synaptic terminal loss in CA4 and redistribution in the molecu lar layer were most frequent in cases with hippocampal sclerosis. Howe ver, both forms of synaptic pathology were also noted in most cases wh ere the pathological findings were classified as indefinite, and in so me cases associated with mass lesions of the temporal lobe. These resu lts support the importance of neuronal loss and synaptic reorganizatio n as possible mechanisms of illness in epilepsy. They also indicate th at synaptic immunostaining may be a useful adjunct to routine neuropat hological diagnostic techniques.