Influence of post mortem changes on experimental safety belt injuries.

Belt protected car occupants involved on head-on collisions do not seem to suffer as severe injuries as unembalmed cadavers subjected to comparable simulated head-on collisions. Therefore it has been questioned if cadavers constitute adequate test specimens for study of thoracic tolerances. This investigation compares injuries in safety belt wearing living and dead pigs which have been subjected to simulated head-on collisions on an acceleration tract. Tests were performed on all 20 pigs (10 living and 10 dead). The arterial side of the circulatory system of the dead pigs was infused. The force in the safety belts, the intraaortic pressure, the impact velocity and the deceleration of the sled were recorded. The tests were high speed filmed. Post mortem examination of the pigs revealed differences in injury severity. Dead pigs more easily suffered rib fractures. Deformation of the rib cage due to stripping of the periosteum and laceration of surrounding tissue occurred mainly in the dead pigs. Laceration of intrathoracic blood vessels was seen in dead pigs while isolated heart lesions were seen only in living animals. The main cause of these differences in tolerance level seems to be post mortem changes of the mechanical properties of the different tissues. The results are valid for pigs but indicate that great care has to be exercised when results obtained from cadaver experiments are evaluated concerning thoracic tolerance.

Rotational cerebral injuries near the superior margin of the brain.

Traumatic lesions near the superior margin of the brain frequently are caused by an anterior or posterior blow to the head. The injuries consist of disruptions of one or a few (with subdural bleeding) or of numerous or all (with instant death or immediate unconsciousness and later death because of simultaneous brain stem injuries) parasagittal bridging veins. Cerebral injuries close beneath the superior margin of the brain occur either alone or together with disruptions of parasagittal bridging veins. These injuries consist mainly of subcortical, perivascular or larger, hemorrhages and of injuries to the white matter. No extensive complete necrosis occurs. The lesions are most frequently found in the posterior part of the superior frontal gyrus and the central gyri and often are combined with brain stem injuries. By reconstruction of trauma events the injuries seem to be caused by a rotational acceleration of the head. By model experiments and simulations it is shown that a rotational acceleration of the skull leads to an "inner deformation" of the brain tissue. This deformation may be the explanation of the subcortical injuries, which are therefore designated rotational cerebral injuries (RC-injuries).