Axonal injury (AI), as defined by amyloid precursor protein (APP) positive axonal swellings, was recorded on a series of line diagrams of standard brain sections divided into 116 sectors to provide an Axonal Injury Sector Score (AISS) ranging from 0 to 116. In this preliminary report the sector scoring method of recording axonal damage and providing a topographic and semiquantitative overview of AI was applied to a series of 11 lateral (4 pedestrian, 1 car occupant and 6 falls) and 7 occipital head impacts (3 pedestrian, 4 falls) for which the biomechanical data was sufficient to estimate peak linear acceleration and impact velocity as a measure of the magnitude of the impacting forces acting on the head. AI was present in all 18 cases, and consisted of a complex mixture of focal and diffuse axonal damage arising by different pathophysiological mechanisms. Lateral impacts produced significant AI at linear accelerations lower than for occipital impacts. Widespread AI was present in all 10 fall cases irrespective of the height of the fall. The lowest AISS was found in the concussive mild head injury case (AISS 5). (A)
Abstract