EEG and clinical studies of the development of alumina cream epileptic focus in split-brain cats

Alumina cream epileptic focus was established in the right sensorimotor cortex in 20 split-brain cats (partial or complete). EEG and behavioral observations were made in a period ranging from 24 to 836 days. Four types of EEG changes after alumina cream injection were differentiated. These types could be related to the direct effects of brain damage and to development of epilepsy. Spikes and sharp waves and paroxysmal discharges (focal and multifocal) were observed in about 60% of the cats. Clinical seizures developed in about the same percentage of the animals. These values are below those reported for cats with intact interhemispheric commissures. Diphenylhydantoin (DPH) was given orally in a daily dose of up to 15 mg/kg body weight in 9 animals with developed epileptic EEG activity. Five of them had epileptic seizures. DPH was introduced not earlier than 1.5 months after intracortical alumina cream injection. The plasma level of DPH varied between 7-20 mug/ml. This dose produced chronic symptoms of intoxication. Neither EEG changes nor clinical seizures were entirely controlled by this drug. Additional doses of Relanium (diazepam), and phenobarbital were necessary to stop generalized seizures or status epilepticus.