Analysis Of Eeg Characteristics Within 30 Minutes Before The Onset Of Focal Epileptic Seizure

Objective:The analysis of EEG characteristics within 30 minutes before the onset of focal epileptic seizure will help improve the understanding of EEG seizure onset characteristics and provide a test data set for the development of intelligent prediction software for focal seizures.Method:We collected 190 children with epilepsy who had focal electrical-clinical seizures or focal electrical seizures monitored by long-range video EEG,extracted the EEG characteristics including abnormal discharge wave amplitude,frequency,waveform changes and distribution within 30 min before seizure onset,recorded them as the evolution pattern and distribution area respectively for statistical analysis,and compared the differences between the focal electrical-clinical seizure group and the focal electrical seizure group.Results:⑴A total of 771 focal seizures were monitored by long-term video-EEG in 190 children with focal epilepsy.There were 166（87.4%）patients with focal electricalclinical seizures and a total of 711（92.2%）seizures.There were 24（12.6%）patients with focal electrical seizures and a total of 60 seizures（7.8%）.⑵There were 34 main distribution areas of abnormal EEG waveforms within 30 minutes before the onset of 771 seizures,among which the distribution areas in no less than 10 patients were mainly unilateral temporal regions with 128（16.6%）seizures in39 cases（20.5%）,unilateral frontopolar-frontal regions with 79（10.2%）seizures in 18cases（9.5%）,unilateral frontal regions with 48（6.2%）seizures in 14 cases（7.4%）,unilateral occipital-posterior temporal regions with 48（6.2%）seizures in 14 cases（7.4%）,unilateral occipital region with 40（5.2%）seizures in 11 cases（5.8%）.⑶There were 14 main evolutionary patterns of EEG abnormal waveforms within30 minutes before the onset of 771 seizures,among which the evolutionary patterns in no less than 10 patients were mainly low amplitude and fast rhythms with 428 seizures（55.5%）in 90 cases（47.4%）,slow wave emanations,paroxysmal or continuous emission with 137 seizures（17.8%）in 33 cases（17.4%）,widespread voltage drop with82 episodes（10.6%）in 20 cases（10.5%）,θ activity with 28 episodes（3.6%）in 12 cases（6.3%）.⑷ The abnormal waveforms in the unilateral temporal region,unilateral frontopolar-frontal region,unilateral frontal region,unilateral occipital-posterior temporal region,and unilateral occipital region with predominant distribution of EEG within 30 minutes before the onset were all predominantly issued with low amplitude fast rhythm,accounting for 22/39（56.4%）,11/18（61.1%）,11/14（78.6%）,8/14（57.1%）,and 8/11（72.7%）,respectively.The abnormal waveforms with no obvious concentrated distribution area were mainly widespread voltage drops（20/22,90.9%）.⑸ The distribution of EEG abnormal waveforms within 30 minutes before the onset of seizure was mainly in the unilateral temporal region in both the focal electricclinical seizure group and the focal electric seizure group,accounting for 18.7%（31/166）and 33.3%（8/24）of the total number of children,respectively.And the EEG abnormal waveforms within 30 minutes before the onset of seizure were mainly issued in low amplitude and fast rhythm,accounting for 44.6%（74/166）and 66.7%（16/24）of the total number of children,respectively.Conclusions:⑴In children with focal epilepsy,the distribution of abnormal EEG waveforms within 30 minutes before the onset of seizures was mainly in the unilateral temporal region,unilateral frontopolar-frontal region,unilateral frontal region,unilateral occipital-posterior temporal region and unilateral occipital regions.⑵In children with focal epilepsy,there were 14 evolutionary patterns of abnormal EEG discharges within 30 minutes before the onset of seizures,predominantly low amplitude and fast rhythm discharges（47.4%）,mainly also including slow wave emission,paroxysmal or continuous emission,widespread voltage drop,θ activity et al.⑶ In children with focal epilepsy,abnormal EEG discharges predominantly distributed in unilateral temporal regions,unilateral frontopolar-frontal regions,unilateral frontal regions,unilateral occipital-posterior temporal regions,and unilateral occipital regions within 30 minutes beforethe onset of seizures are mostly issued with low amplitude and fast rhythm,and children without concentrated distribution regions are mainly with widespread voltage drop.⑷The distribution of abnormal discharges in the 30 minutes before the onset of focal electrical-clinical seizures was dominated by unilateral temporal region,no obvious concentrated distribution region and unilateral frontopolar-frontal region.And the evolution pattern was dominated by low amplitude and fast rhythm,slow wave emission,paroxysmal or continuous emission and extensive voltage drop.The focal electric seizure group was mostly unilateral temporal area,unilateral occipital-posterior temporal area and unilateral occipital area,and the evolution pattern was mainly low amplitude and fast rhythm,θ activity and slow wave activity.