[Statistics and reinvestigation of the 4/s variant of basic EEG activity (author's transl)]

We selected our patients from 1961 to 1973 (60 500 patients, 66 661 EEG recordings) for the 4/s variant of EEG activity according to the characteristics described in the literature. In 1.9% (115 patients) this EEG variant was evident. In addition, 25 out of 50 variant patients from this group were reexamined. In regard to amplitude, local distribution, frequency concentration around 4/s, our findings concur with those of other authors. Slower frequencies of the 4/s variant occur more often at advanced age. The age median was 32.7 years compared with 42.5 years in the rest of the cases examined in the clinic and out patient clinic over a period of 15 years. This age difference is significant (P less than 0.001). The 4/s variant did not occur more often in men than in women. Only the most common clinical diagnosis, vascular headache or migraine (36%), occurred with significantly higher incidence in 4/s variant patients (P less than 0.001). Other clinical diagnoses showed the same distribution in EEG variant patients and other patients of this clinic. EEG reexaminations carried out over a long period of time are an important criterion in evaluating 4/s activity in the posterior regions of the cranium as a--possibly constitutional--4/s variant of basic cerebroelectric activity.