Alumina cream-induced focal motor epilepsy in cats. IV. Peduncular and midline tegmental lesions.

The effect of peduncular and midline tegmental lesions on EEG-EMG patterns of type B and C alumina cream-induced focal motor seizures was studied on cats with chronically implanted electrodes and cannula lesion systems. EEG patterns included number, amplitude and contralateral propagation of type B spikes and occurrence and duration of type C tonic-clonic discharges. EMG patterns included phasic multiple unit activity (EMG MUA) time locked to the onset of type B EEG spikes and time locked to the onset (contradversive OTCD) and end (clonic ETCD) of type C tonic-clonic EEG paroxysmal discharges. (1) Lesions of the middle third of the cerebral peduncle, ipsilateral to the cortical epileptogenic focus, blocked type B muscular convulsions and significantly decreased phasic EMG MUA at contralateral face, neck and limbs. (2) Bilateral peduncular lesions blocked clonic type C muscular convulsions and significantly decreased phasic clonic ETCD EMG MUA at the same body regions. (3) Midline tegmental lesions blocked phasic type C muscular convulsions and significantly decreased phasic contradversive OTCD EMG MUA at neck muscles. (4) Bilateral peduncular lesions significantly increased and midline tegmental lesions significantly decreased (below the previous interictal) contradversive OTCD EMG MUA. (5) Neither peduncular nor midline tegmental lesions significantly changed EEG patterns of type B and C seizures.