Correlation between EEG Abnormality and Age in Childhood

A total of 2,325 electroencephalographic (EEG) records, obtained in 956 children (555 male, 401 female) who visited our outpatient clinic at under 5 years of age because of convulsions, were analyzed for correlation between EEG and age.

1. In the first 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 first examination. The importance and usefulness of repeated EEG examinations were emphasized.

2. The appearance of spike abnormality was found to be correlated with the age of patients: that in children 3 years of age and over (40–60%) was higher than that in those less than 3 years old (6–26 %) on the first examination. The follow-up examinations showed a correlation similar to that on the first examination as well.

3. Certain types of spike abnormality appeared more likely to occur in their own favourable 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.

4. To detect subjects with potential spike EEG abnormality, examination at 3 years of age and follow-up observation are most useful. The follow-up observations are even more important when the first examination is made at less than 3 years of age.

EEG - age - follow-up - febrile convulsions - nonfebrile convulsions