Since CT scans make it possible to demonstrate precise morphological and anatomicopathological findings, small brain lesions are frequently found on CT scans, in spite of the short duration of unconsciousness after head trauma.
Thirty six out of approximately 500 cases which received CT examinations within two weeks after head injury were selected and analyzed. In these cases, almost all high or low density lesions were detected in the tip and/or base of the frontal and/or temporal lobes adjacent to the skull. Causes of the injury were traffic accidents (33.3%), falls on the floor or road (33.3%), and falls down stairs, out of beds, etc. (25.5%). Clinical manifestations before CT examinations were heaviness in the head or headache (36.0%), and nausea and vomiting (33.3%), but thirteen out of 36 patients had no symptoms or complaints. None of the 36 patients showed any neurological dysfunctions suggesting focal damages.
Fourteen of the above-mentioned 36 patients (38.9%) had skull fractures and the remaining 22 (61.1%) did not, and there was no significant difference between the two. On the contrary, the incidence of skull fractures in cases in which CT scans were normal was 12.4% which was significantly different from the figure of 38.9% in patients with fractures and CT abnormalities. It is inferred that the deformation of the skull at the time of impact is one of the important factors in the development of brain contusions.
To clarify the correlation between the duration of the initial unconsciousness and abnormal CT findings, 219 consecutive cases of head injuries underwent CT scans without considering their severity. Out of 171 patients who were conscious or lost consciousness in less than 10 minutes, 13 (7.6%) had small lesions in CT scans. Of 12 cases with a state of unconsciousness from 10 to 60 minutes in duration, three (25.0%) had abnormal CT findings. In all cases which were unconscious for more than 6 hours, brain lesions were detected by CT scans.