An animal model of nonconvulsive status epilepticus: A contribution to clinical controversies

Purpose: To characterize electroencephalographic and behavioral effects as well as electrophysiologic and morphologic consequences of a subconvulsive dose of pilocarpine in lithium chloride-pretreated rats. Methods: Pilocarpine (15 mg/kg) was administered intraperitoneally to adult rats pretreated with lithium chloride (3 mEq/kg, i.p.). Behavior was obser ved for 2 h and videotaped in three consecutive sessions. At the same time, EEO was recorded from the sensorimotor cortex and the dorsal hippocampus. Threshold intensities of currents necessary to elicit hippocampal afterdisc harges were determined 24 h and 1 week after the pilocarpine administration . The brains were histologically examined 1 week after pilocarpine administ ration using Niss1 stain. Results. Pilocarpine induced time-limited nonconvulsive status epilepticus (NCSE). Epileptic EEG activity concurrent with prominent behavioral feature s was observed both in the neocortex and, predominantly, in the hippocampus . No changes in afterdischarge thresholds were observed in the dorsal hippo campus 24 h and 1 week after NCSE. One week after NCSE, seizure-related bra in damage was found mainly in the motor neocortical fields. Conclusions: Pilocarpine-induced NCSE in rats strongly resembles a short-te rm human complex partial status epilepticus. Our animal model is suitable f or studying the possible adverse effects of prolonged nonconvulsive seizure s.