Descending systems contributing to locomotor recovery after mild or moderate spinal cord injury in rats: experimental evidence and a review of literature.

PURPOSE: Locomotor recovery after spinal cord contusion injury (SCI) may be mediated by descending axons spared at the lesion epicenter. Greater axonal sparing is associated with more extensive recovery. Therefore, we identified the source and relative proportion of spared axons associated with extensive or limited locomotor recovery after SCI.

METHODS: Female Sprague Dawley rats underwent mild or moderate SCI using the OSU device.

RESULTS: Locomotor recovery was greater for the mild than moderate group with the primary differences being restitution of limb coordination, very little toe dragging and minor paw rotation.

CONCLUSIONS: The following brain nuclei with substantial neuronal labeling after mild but not moderate SCI may play an important role in locomotor recovery: raphe pallidus and magnus, ventral medullary and pontine reticular formation, lateral vestibular nucleus, red nucleus and locus coeruleus. We review the normal anatomical distribution of descending systems to the lumbar cord in rat and the role they play in motor control.