Variable electrobehavioral patterns during focal nonconvulsive status epilepticus induced by unilateral intrahippocampal injection of kainic acid

Summary Objective Nonconvulsive status epilepticus (nc SE ) is a severe condition that may result in neurologic sequelae and epilepsy resistant to pharmacologic treatment. We analyze here seizure and electroencephalography ( EEG ) patterns and their correlation to the development of a chronic epileptic condition in a guinea pig model of focal nc SE induced by intrahippocampal injection of kainic acid ( KA ). Methods Electrobehavioral patterns during nc SE induced by unilateral injection of 1 μg of KA in the CA 1 region of the hippocampus were characterized by continuous video‐ EEG monitoring in 13 guinea pigs bilaterally implanted with recording electrodes in the hippocampus and neocortex. Results Video‐ EEG analysis demonstrates a high variability of seizure type and duration during KA ‐induced nc SE . Seizures showed focal signs correlated with diverse epileptiform EEG discharge distributions, either diffuse or localized. Nonfocal (bilateral motor) signs during seizures most likely correlated with a diffuse EEG pattern. The evolution into a chronic epileptic condition correlated neither with the severity of seizure pattern nor with the diffusion of the EEG discharges observed during the nc SE . Significance Video‐ EEG monitoring in a guinea pig model of nc SE induced by unilateral hippocampal injection of KA demonstrates a high variability of electrobehavioral patterns. We demonstrate that the seizure severity score during focal nc SE is not a predictor of the evolution into a chronic epileptic condition of mesial temporal lobe epilepsy.