Abstracts

Rationale: There has been an evolution of the hypotheses to explain the electrical generation of the spike and wave pattern. Dynamic systems modeling of the EEG may provide insights into the mechanisms. Childhood absence epilepsy (CAE) is a frequent seizure type in school age children. Children have periods of impaired attention coincident with the 3 hertz (Hz) generalized spike and slow wave. The phenomena of the 3 Hz spike and wave is poorly understood. This form of epilepsy, which has uniform EEG findings, is a useful group to apply dynamic measure to as a cohort, which has not been done yet. Methods: The electroencephalogram (EEG) of 12 children, meeting the ILEA criteria for childhood absence epilepsy, were examined. All data were acquired using Nicolet BMSI hardware to record a 24 channel (EEG) using the international 10/20 of Electrode placement. The EEG was recorded for up to 1 hour. EEG records were reviewed using 15 mV per millimeter sensitivity with high voltage filter at 15 Hz and low frequency filter set at 1.0 Hz. The F7 channel of the EEG was selected for actual analysis. The EEG seizure data was converted to a cvs file. whic was read by a MatLab macro, with each point in time contained in the .cvs file. The analysis program rrChaos was used to calculate dyanamic measures ananlysis. Calculations include principle eigen value, average Mann-Whitney, correlation dimension, kolomolov entropy in bits/second, absolute noise level as dimensionless units, and an average of b. All data points were plotted with time on the x-axis and the data values on the y-axis for the selected measures. Average sores of the calculations ere made and averaged over time. Results: Over the cohort of CAE patients, the eigen values and correlation dimension both decrease at the onset of the absence seizure, while entropy increases, at times, in a complex fashion at the onset of the seizure. As a group, the seizures progress with correlation dimension and eigen values slowly increasing to baseline at seizure termination. Entropy slowly decreases to baseline after seizure onset. All measures were compared to baseline EEG dynamics which were stable over the time period. These dynamic changes over the course the absence seizure in the cohort of CAE patients has been previosuly described as phase space plots with similar dynamic changes. These dynamic measures are able to further explore the complexities of the driving function of the absence seizures within the cohort of patients with CAE. Conclusions: 1. The changes in these dynamic measures at the onset of the absence seizures have been described previously in other analysis of other types of focal and generalized seizures. 2. The dynamic measures applied to the EEGs of a cohort of CAE patients show changes in the dynamics as the seizure progresses not previously described. 3. The findings of the dynamic measures were similar across this cohort of CAE patients, not previously described.