Correlation between EEG Abnormality and Age in Childhood

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Abstract
A total of 2325 EEG records, obtained in 956 children (555 male, 401 female) who visited an outpatient clinic at under 5 yr of age because of convulsions, were analyzed for correlation between EEG and age. In the 1st group of EEG records, spike abnormality was found in 35% (332/956). The spike abnormality was detected in 114 after repeated examination of 194 children (59%) who had had no such abnormality on the first examination. Only 74% (332/446) of the patients who had had spike abnormality at least once revealed it on the 1st examination. The importance and usefulness of repeated EEG examinations were emphasized. The appearance of spike abnormality was correlated with the age of the patients: that in children 3 yr of age and over (40-60%) was higher than that in those < 3 yr old (6-26%) on the first examination. The follow-up examinations showed a correlation similar to that on the first examination as well. Certain types of spike abnormality appeared more likely to occur in their own favorable age ranges: hypsarrhythmia at ages 0-2, focal spike at ages 0-1, polyspikes at ages 0-3, 2.5/s spike-and-wave complex (sp-w-c) at ages 2-6, slow wave burst with spike at ages 2-6, irregular sp-w-c at ages 4-5, 3/s sp-w-c at ages 4-7, 4/s sp-w-c at ages 6-14, sporadic spike at ages 7-10 and spike with slow wave at ages 11 and over. To detect subjects with potential spike EEG abnormality, examination at 3 yr of age and follow-up observation are most useful. The follow-up observations are even more important when the 1st examination is made at < 3 yr of age.