Harden et al. have reported the importance of EEG features and evolution [16] , as confirmed by the observations in the present study, the initial EEG features appeared abnormal in all patients. However, in the initial EEG features, it is usually difficult to distinguish HSES from other diseases with convulsions including febrile convulsions. Rosman has reported that the initial EEG features in patients with febrile convulsions are abnormal in as many as 88% of the patients [17] .