Mathematical simulation of gliding contusions.

A gliding contusion in the acute phase is characterized by a streaklike hemorrhage of venous origin situated subcortically in a paramedial convolution. In later stages perivascular necrosis may develop. This type of injury is caused by head angular acceleration and is often seen in traffic casualties when the head has hit the steering wheel, the dashboard or the windshield. The deformation of the brain matter close to the superior sagittal sinus has been simulated by means of a mathematical viscoelastic model in order to clarify the genesis of the gliding contusions. The blood vessels in the brain matter will be strained as a consequence of the brain deformation which results from head angular acceleration. The highest values of the strain occur subcortically where the blood vessels are injured first. The tolerance levels for gliding contusions have been deter- mined. The calculations which were based on experiments regarding the dynamic properties of the superior cerebral veins and on two alternative injury criteria proposed, indicate that a gliding contusion is not likely to arise if the maximal angular acceleration does not exceed 4500 rad/sec' or the change in angular -velocity does not exceed 70_rad/sec. INTRODUCHON Lindenberg and Freytag (1960) have described exten- sive hemorrhages of traumatic origin which were sit- uated subcortically in the paramedial parts of the cer- ebral hemispheres. The hemorrhages were of venous nature and were considered to be caused by deforma- tion of the brain matter when the head was subjected to angular acceleration. The lesions were designated as gliding contusions. For consecutive autopsy mater- ial Voigt and Lawenhielm (1974) have demonstrated similar injuries in 25% of traffic casualties. Also in these cases a head angular acceleration had occurred. The hemorrhages were however not always as exten- sive as in the description by Lindenberg and Freytag (1960). They appeared 'as streaklike perivascular bleedings mostly found in the back aspect of the fron- tal superior gyrus and in the upper part of the anter- ior central convolution. The hemorrhages seemed to originate from intracerebral portions of the superior cerebral veins. In victims surviving more than one week areas with necrosis or perivascular glial scars often running deeply into the white matter could be found. Remarkably the peripheral layers of the brain cortex remained intact in spite of sometimes extensive injuries. Brain injuries due to head impact can be very com- plex. The gliding contusion may be part of such an injury pattern but may as well not be present. On the other hand gliding contusions can occur alone. Different mechanisms of origin probably account for these differences. Although lesions of the gliding con- tusion type are quite common in traffic accidents they have attracted little attention in the literature. There- fore an investigation to clarify the genesis of the glid- ing contusion and thereby make it possible to predict threshold levels was needed. * Received 15 Jffrzuury 1975.