The astroglial response to Wallerian degeneration after spinal cord injury in humans.

We describe the changes exhibited by astrocytes in areas of Wallerian degeneration after spinal cord injury in humans using glial fibrillary acidic protein immunohistochemistry correlated to standard histology at time points ranging from 8 days to 23 years after injury. Astrocytes were slow to react; a slight increase in immunoreactivity was observed at 4 months. Over time they began to lose immunoreactivity in both the somata and the processes as the debris from the degenerative process was cleared. By 1 year after injury the staining intensity had decreased to levels which were lower than in normal areas of the cord. This hypointense staining persisted for at least 23 years after injury. These findings are significantly different from those observed in animal studies and emphasize the need for additional pathological studies of human spinal cord injury.