[Posttraumatic epilepsy.  Clinical aspects and electrophysiological foundations]. 
The review of the syndrome is centered on time course, prognosis and prophylaxis.  Prophylactic anticonvulsive treatment depends on the prognosis.  The latter is dependent on the risk to develop epilepsy after a certain type of head injury.  Treatment should begin in the high risk group of patients before seizures become overt.  In order to avoid preventive treatment in unselected posttraumatic cases, predicting the risk in each case is most important.  Therefore the literature was reviewed selecting injuries and complications of high risk.  Knowledge on pathophysiologic mechanisms in the epileptogenic focus to a large extent stems from animal experiments using a model of chronic recurrent seizures.  Basic electrophysiologic mechanisms responsible for focal electroencephalographic changes were studied by recording from single cells.  Profound abnormalities in patterns of neuronal discharge were found as well as morphological and functional changes of glia in the epileptogenic scar.  It appears that glia is important in generating focal electroencephalographic spiking.  By controlling intercellular potassium transport glia modulates neuronal activity.