Relationship between epileptic activity and edema formation in the acute phase of cryogenic lesion.

Following cryogenic lesions of the brain in the rabbit, ictal activity appears within min with a maximum at 2 h. Brain edema increases rapidly between 2-4 h with a maximum at 8 h. The glutamate concentration reaches 209% of control in the perilesional area at 2 h and the time course of glutamate/GABA ratio parallels the time course of epileptic activity. The impairment of Na+-K+-ATPase activity (rise of KMapp for K+) in the glial fraction coincides with the increase of edema. A positive correlation is found between the total amount of ictal activity and the total amount of edema in individual animals, suggesting that epilepsy may enhance edema formation.