The course of the traumatising force in acceleration head injury: CT evidence.

Since brain damage in closed head injury of acceleration-deceleration type depends on the site of impact and on the course of the traumatising force, a reconstruction of these was attempted using CT. The study included 45 standard CT studies of adults with closed acceleration-deceleration head injuries. We selected 32 patients exclusively on the basis of CT findings of soft tissue contusion, skull fractures and cerebral contusions (coup and/or contrecoup, as well as other parenchymal lesions), while in the remaining 13 patients clinical findings were also used. On CT, the axial section of the skull was divided into 12 sections imitating the clock-face, to permit computerised graphic presentation of the direction of the traumatising force. Analysis of cerebral contusions on different CT studies in each case allowed location of "dominant coup" and "dominant contrecoup" lesions to be determined. The site of impact and the course of the traumatising force were reconstructed and graphically presented on the basis of these findings, supplemented with data on soft tissue contusions (present in 71% of cases), skull fractures (in 36%) and sometimes on other brain lesions. Comparison of the computerised graphic presentation of the site of impact and direction of the traumatic force and the location of lesions revealed a high correlation between them. In 80% of cases, the site of impact could be visualised only by CT. The acceleration force acted along the longer axis of the head (centroaxial or semioblique) in 87% and along the shorter axis in 13% of cases. Multiple lesions were found in 87% of cases. The lesions were most frequent in the frontal (51%) and temporal (26%) lobes. CT was very useful for reconstruction of the site of impact and of the course of the traumatising force in acceleration head injury. Data obtained by this procedure may have far-reaching prognostic and forensic implications.