EPILEPTIC SEIZURE ACTIVITY IN THE ACUTE-PHASE FOLLOWING CORTICAL IMPACT TRAUMA IN RAT

The aim of this investigation was to determine the incidence of seizur e activity in the acute phase following traumatic brain injury. Compre ssion contusion trauma was produced in the right parietal cortex in 19 artificially ventilated rats. Electroencephalographic recordings were carried out in 17 of the animals for 2 h following the impact. The ex tracellular levels of neuroactive amino acids were simultaneously moni tored in 9 of the experiments using microdialysis. In 14 of the 17 ani mals a generalized seizure activity with an average duration of 59s (r ange 30-101s) was recorded. The mean time lag between trauma and seizu re onset was 67s (range 26-90 s). The seizure activity was consistentl y followed by post-ictal depression. The trauma was accompanied by a t ransient increase of aspartate, taurine, glutamate and glycine, in dec reasing rank order. The seizure activity occurred when the levels of t hese neuroactive amino acids were elevated. It is concluded that the h igh incidence of seizure activity observed may be an important factor contributing to secondary ischemia after traumatic brain injury. Aspar tate and glutamate, potentiated by glycine, may play a role in post-tr aumatic seizure activity.