85. the Statistical Consideration of the EEG Changes Following Head Injuries in Our Clinic

The statistical consideration on 613 cases (490 of males, 123 of females) was studied by EEG in 1334 cases of head injury treated in our clinic during past 6 years (1958-1963). Abnormality of the EEG activity was found on 276 cases (45%). it was studied that the relation between the incidence of the abnormal EEG activity and severity of head injures classifying into four types according to Ch. Araki. The abnormal activities were found in 35.5%, 42.0% 63.2x/ and 47.2% in the first, second, third and fourth types respectively. Therefore, the most highest incidence of the abnormal activity was found in the III type, and there was no conspicuous difference between the II and IV types. Seizure discharges were observed in 117 of 613 cases (19.1%) . It was reported that the variations in EEG rhythm characteristic of epilepsy are to be found in some 10% of the population, while clinically recognizable epilepsy was found in higher percentage in cases of head injury 20 of 1334 cases (1.5%/) than in the total population (0.2-0 .5 %/ ). Seizure discharges in 108 of the above written 117 cases showing epileptic patterns were induced with intravenous injection of the activating drug (megimide) . It is noted from the facts that the use of activating drugs is important for the EEG study of the posttraumatic patient. There was no significant difference in the occurrence of seizure discharges in 4 types of head injuries , 16.1 %/, 18.1%, 18.4% and 11.3% respectively. These results show the existence of a parallelism between , the incidence of the abnormal EEG activity and the 4 types of head injuries , but no strict correlation between the morbidity of the posttraumatic epilepsy and the head injury types. Therefore, it may be suggest that importance of constitutional disposition as a basis for development of traumatic epilepsy.