Retrograde changes in the corticospinal tract of posttraumatic paraplegics.

Autopsy material from patients with posttraumatic paraplegia of long duration was examined to determine the extent of survival of corticospinal axons proximal to the injury. Spinal cord sections from sites above a functionally complete spinal cord injury were examined for the presence of axons, myelin, and gliosis. There was a marked depletion of axons from the corticospinal tract close to the region of injury. There appeared to be a gradual increase in the density of axons within the tract at increasing distance from the injury in all patients. Corticospinal axons appear to retract from the spinal cord injury site, but do not show progressive degeneration even years after a spinal cord injury.