Automatic detection of spike and wave discharges in the EEG of genetic absence epilepsy rats from Strasbourg.

Genetic absence epilepsy rats from Strasbourg are a strain of Wistar rats in which all animals exhibit spontaneous occurrences of spike and wave discharges (SWDs) in the EEG. In this paper, we propose a novel method for the detection of SWDs, based on the key observation that SWDs are quasi-periodic signals. The method consists of the following steps: 1) calculation of the spectrogram; 2) estimation of the background spectrum and detection of stimulation artifacts; 3) harmonic analysis with continuity analysis to estimate the fundamental frequency; and 4) classification based on the percentage of power in the harmonics to the total power of the spectrum. We evaluated the performance of the novel detection method and six SWD/seizure detection methods from literature on a large database of labeled EEG data consisting of two datasets running to a total duration of more than 26 days of recording. The method outperforms all tested SWD/seizure detection methods, showing a sensitivity and selectivity of 96% and 97%, respectively, on the first test set, and a sensitivity and selectivity of 94% and 92%, respectively, on the second test set. The detection performance is less satisfactory (as for all other methods) for EEG fragments showing more irregular and less periodic SWDs.

Vagus nerve stimulation for refractory status epilepticus.

We report on the long-term follow-up of a patient with refractory non-convulsive SE who was successfully treated with VNS. A 7-year old girl with a medical history of thrombosis in the right internal cerebral vein and right thalamic bleeding 8 days after birth, developed epilepsy at the age of 13 months. At the age of 6 she presented with a refractory non-convulsive SE. A vagus nerve stimulator was placed after 11 days of thiopental-induced coma. Three days after VNS implantation, the thiopental-induced coma was successfully withdrawn and electroencephalography showed normalization one week after start of VNS. After a follow-up of 13 months she remains seizure-free and AEDs have been partially tapered. This case illustrates a potential acute abortive effect with sustained long-term seizure reduction of VNS in a 7-year old girl who presented with refractory non-convulsive SE.

High frequency deep brain stimulation in the hippocampus modifies seizure characteristics in kindled rats.

PURPOSE: This experimental animal study evaluates the effect of high frequency deep brain stimulation (HFS DBS) on seizures in the Alternate Day Rapid Kindling model for temporal lobe epilepsy (TLE). The target for HFS is the hippocampus, as this structure is often presumed to be the seizure focus in human TLE. METHODS: Rats (n = 12) were fully kindled in the hippocampus according to the Alternate Day Rapid Kindling protocol. Characteristics of the evoked afterdischarges (AD) were determined in the baseline period using AD threshold, AD latency, and AD duration as parameters. Rats were divided into a treated group (n = 7) that received 130 Hz HFS for 1 week, and a control group (n = 5) that did not receive HFS. Rats were retested in the following week. After 1 additional week of rest, the HFS group was continuously stimulated again for 1 week, during which AD evoked by kindling stimuli were characterized again. RESULTS: HFS had a direct effect on evoked AD: during HFS, it increased AD threshold to 203 +/- 13% of controls (p < 0.01) and increased AD latency to 191 +/- 19% (p < 0.05). It decreased AD duration to 71 +/- 9% (p < 0.05) of controls. The effect outlasted the HFS stimulation as in the week following HFS similar differences, but smaller in size, could still be established. CONCLUSION: Continuous HFS (130 Hz) in the hippocampus of epileptic rats modulates the characteristics of evoked AD in a way that reflects a reduction in excitability of the target region.

Neuromodulation with levetiracetam and vagus nerve stimulation in experimental animal models of epilepsy.

Epilepsy is a neurological disorder consisting of recurrent seizures, resulting from excessive, uncontrolled electrical activity in the brain. Epilepsy treatment is successful in the majority of the cases; however; still one third of the epilepsy patients are refractory to treatment. Besides the ongoing research on the efficacy of antiepileptic treatments in suppressing seizures (anti-seizure effect), we want to seek for therapies that can lead to plastic, neuromodulatory changes in the epileptic network. Neuropharmacological therapy with levetiracetam (LEV) and vagus nerve stimulation (VNS) are two novel treatments for refractory epilepsy. LEV acts rapidly on seizures in both animal models and humans. In addition, preclinical studies suggest that LEV may have antiepileptogenic and neuroprotective effects, with the potential to slow or arrest disease progression. VNS as well can have an immediate effect on seizures in epilepsy models and patients with, in addition, a cumulative effect after prolonged treatment. Studies in man are hampered by the heterogeneity of patient populations and the difficulty to study therapy-related effects in a systematic way. Therefore, investigation was performed utilizing two rodent models mimicking epilepsy in humans. Genetic absence epilepsy rats from Strasbourg (GAERS) have inborn absence epilepsy and Fast rats have a genetically determined sensitivity for electrical amygdala kindling, which is an excellent model of temporal lobe epilepsy. Our findings support the hypothesis that treatment with LEV and VNS can be considered as neuromodulatory: changes are induced in central nervous system function or organization as a result of influencing and initiating neurophysiological signals.