Alterations of the electroencephalogram sub-bands amplitude during focal seizures in the pilocarpine model of epilepsy

Introduction: Temporal lobe epilepsy (TLE) is the most common and drug resistant epilepsy in adults. Due to behavioral, morphologic and electrographic similarities, pilocarpine model of epilepsy best resembles TLE. This study was aimed at determination of the changes in electroencephalogram (EEG) sub-bands amplitude during focal seizures in the pilocarpine model of epilepsy. Analysis of these changes might help detection of a pre-seizure state before an oncoming seizure. Methods: Rats were treated by scopolamine (1mg/kg, s.c) to prevent cholinergic effects. After 30 min, pilocarpine (380 mg/kg, i.p) was administered to induce status epilepticus (SE) and 2 hours after SE, diazepam (20 mg/kg, i.p) was injected to suppress the seizures. EEG was recorded in the epileptic rats by superficial electrodes. EEG signal in each rat was decomposed to its sub-bands alpha, beta, gamma, theta and delta by Daubechies wavelet transform. The power (square of amplitude) of sub-band during focal seizures was compared with the same sub-band in pre-ictal stage and the percent of changes in each rat was calculated. Results: SE occurred in 65% of the animals and happened 39.4±5.4 min after injection of pilocarpine. Focal and generalized seizures were developed 3.8±0.4 and 7.0±0.5 days after SE, respectively. Although power of EEG and its sub-bands decreased during focal seizures, the changes were not statistically significant. The greatest decrease in power pertained to beta and gamma sub-bands, while alpha and theta sub-bands underwent the least changes. Conclusion: Based on the protocol used in this study, it seems that the power of EEG sub-bands does not change during focal seizures in pilocarpine model of epilepsy.