Abstracts

Rationale: Transcutaneous electrical stimulation (TcES) via concentric ring electrodes was previously shown to attenuate seizure behavior induced by pilocarpine. Here we evaluated the effect of TcES on seizures induced by pentylenetetrazole (PTZ) in rats.Methods: Male Sprague-Dawley rats weighing 290-330gms were briefly anesthetized, shaved and concentric ring electrodes were attached to their scalp one day before the experiment. PTZ (45mg/kg) was given intraperitoneally. Laplacian EEG was recorded from tri-polar concentric electrodes on the scalp. TcES (50 mA, 200 µs, 300 Hz, 2 min, symmetrical, biphasic, charge-balanced) was applied 1 min after the onset of myoclonic jerks. Behavioral activity was scored as R=0: no seizure activity; R=1: oral-facial movements only; R=2: head nodding; R=3: myoclonic jerks; R=4: forelimb clonus; R=5: rearing with forelimb clonus. Control rats received PTZ without passing any current through the electrodes.Results: In the control group (n=5), the rats exhibited myoclonic jerks with a latency of less than 5 min and then progressed from myoclonic jerks through rearing with forelimb clonus; repeated seizure episodes were observed over at least a 15 min period. Electrographic signs of seizure activity, (short high-frequency bursting) preceded the behavioral activity and continued for over an hour after the behavioral activity had ceased. Following stimulation, TcES treated rats (n=3), did not progress to either R=4 or R=5; 2 of these rats exhibited no behavioral activity and the 3rd exhibited only a few myoclonic jerks. Whereas a mean of 8 seizure episodes were observed in controls, TcES treated rats had a mean of 2 seizure episodes. The electrographic activity reverted to baseline following the application of TcES, indicating that electrographic seizures were attenuated in parallel with the behavioral seizures. There was a significant difference in the number (p=0.036) and duration (p=0.045) of convulsions between the TcES treated rats and controls.Conclusions: The noninvasive stimulation applied via concentric ring electrodes appears to effectively suppress the progression of behavioral and electrographic seizure activity after it has been initiated by systemic PTZ. Moreover, the stimulation shortened the duration of behavioral seizures and eliminated a prolonged period of electrographic abnormality that followed the cessation of behavioral seizures. Thus, TcES may be a novel therapeutic intervention for the treatment of acute or chronic seizures.