Status epilepticus: A new rodent model

Abstract Kindling, the phenomenon of producing a persistently seizure-prone area of brain by administering repetitive low intensity electrical stimulation, has recently undergone intensive investigation. The most commonly used interstimulus interval in these experiments has been 24 h. We have found, using an interstimulus interval of one minute, that it is possible to produce long-term self-sustained seizures (SSS) in mice via hippocampal electrode placements. These results suggest an animal model for the clinically-defined syndrome of status epilepticus . Effective stimulus parameters for the production of SSS were a 1.0 sec, 400 μA (constant current) train of 60 c/sec 1 msec biphasic square wave pulses. The intertrain interval was 60 sec. With stimulating electrodes located in hippocampal subfields CA 2 , CA 3 , CA 4 or in the dentate gyrus a slowly developing form of SSS (Non-Lethal SSS) was seen. This form of seizure was characterized by a slow (100–130 stimulation) increase in the intensity and duration of afterdischarge. Behaviorally the major manifestations of Non-Lethal SSS were automatisms or stereotyped behaviors (repetitive grooming, chewing, etc.) and behavioral arrest. These animals displayed performance deficits to an inhibitory avoidance task 24–48 h after the cessation of SSS. Electrode placements in subfield CA 1 of hippocampus generally resulted in a more quickly (40–50 stimulations) developing form of SSS (Lethal SSS). Behaviorally these mice exhibited both preconvulsive and convulsive motor activities. All CA 1 -stimulated animals died in convulsion within 1 h of the onset of SSS. Non-Lethal SSS is discussed as a model for psychomotor status epilepticus . Lethal SSS is discussed as a model for convulsive status epilepticus .