Alumina cream induced focal motor epilepsy in cats. VI. Excision of the perilesional cortex.

The effect of surgical excision of dorsolateral, ventromedial and combined (dorsolateral-ventromedial) perilesional cortices on EMG-EEG patterns of alumina cream induced focal motor seizures was studied in cats with chronically implanted electrodes. EMG patterns included clinical convulsions and related EMG-multiple unit activity. EEG patterns included number, amplitude, polarity and contralateral propagation of type B isolated spikes and type C tonic-clonic paroxysmal discharges. (1) Dorsolateral decortications abolished isolated jerks and related EMG-multiple unit activity and blocked propagation with no effect on number, amplitude and polarity of EEG spikes of type B seizures (epilepsia partialis continua). Dorsolateral decortications reduced contraversion and repetitive jerks and related EMG-multiple unit activity with no changes in number, amplitude, polarity and propagation of EEG tonic-clonic paroxysmal discharges of type C seizures (adversive epilepsy). (2) Ventromedial decortications decreased the number but neither changed jerks and related EMG-multiple unit activity nor amplitude, polarity, propagation of EEG spikes of type B seizures. Ventromedial decortications abolished contraversion and jerks and related EMG-multiple unit activity and reduced number, amplitude and duration with no changes in polarity and propagation of EEG paroxysmal discharges of type C seizures. (3) Combined decortications abolished jerks, contraversion and related EMG-multiple unit activity with a variable effect on EEG patterns of type B and C seizures. In 4 cats, combined decortications abolished while in other 2 cats decreased the amplitude and reversed the polarity of type B spikes and reversed the polarity and blocked the propagation of type C paroxysmal discharges.