The conformation of the brain plays an important role in the distribution of diffuse axonal injury in fatal road traffic accident.

Objective: A study was made of the brain lesions in 120 random victims of fatal road traffic accidents to determine the frequency and topographic distribution of diffuse axonal damage (DAI) in relation to the midline brain structures.

Method: The identification of axons was carried out with a mouse antibody anti-neurofilament proteins 70-, 160-, and 210-kD.

Results: DAI was identified in 96 (80%) brains and classified as Grade 1 in 21.9%, as Grade 2 in 51%, and as Grade 3 in 27.1% of the patients. In spite of the diffuse distribution that is characteristic of DAI, damage occurred preferentially in the interhemispheric formations (corpus callosum and fornix) and rostral portion of the brainstem, usually to one side of the midline.

Conclusion: From a mechanical point of view, the interhemispheric formations and the rostral portion of the brainstem act as fixating structures for the cerebral hemispheres during rotational acceleration of the head. It is known that the motion of the cerebral hemispheres is delayed at the points of fixation, where greater stress would be produced, particularly on the side subjected to greater displacement. The frequent involvement by DAI of deep, center-medial brain structures, usually to one side of the midline, supports the mechanism proposed above.