Penicillin epilepsy in the rabbit

The effects of penicillin perfusion were studied in 16 rabbits with chronically implanted electrodes in the sensorimotor and in the visual cortex of both hemispheres. In 14 rabbits, at an average dose of 1,279,966 IU/kg, penicillin caused the appearance of generalized spikes or polyspikes accompanied by massive myoclonic jerks. Sometimes massive myoclonic jerks without EEG epileptic activity were seen. In one animal only spinal myoclonic activity without EEG epileptic abnormalities occurred. Three of these rabbits developed, after a mean penicillin dose of 2,193,174 IU/kg, generalized seizures accompanied on the EEG by bilateral and synchronous discharges of spike or polyspike and wave complexes. The effect of penicillin was tested also in a group of four rabbits in which a small cortical vascular lesion was made, and in another group of four animals with electrodes implanted into the hippocampus. Rabbits with a vascular lesion and those with hippocampal electrodes developed a focal epilepsy at a mean dose of 1,286,804 IU/kg. In the rabbits with the cortical lesion, the seizures started always from the site of the lesion. In the group of animals with the hippocampal electrodes, the seizures could begin, even in the same rabbit, from the hippocampus or from the cortex over the implanted electrode. Penicillin in the rabbit produces a predominantly myoclonic form of seizure disorder and only rarely organized generalized seizures similar to those observed in the cat. Under circumstances in which a local breakdown of the blood-brain barrier has been created, it induces focal seizure discharges that become often secondarily generalized.