Abstract:

Brachial as well as lumbosacral plexus avulsion injuries are usually caused by high kinetic traumas, such as car-pedestrian, car and motorcycle accidents or falls from great heights. Traction forces affecting the head and shoulders or extremities pull the spinal nerve sleeves away from the spinal cord thus tearing and rupturing the postganglionic spinal root until it is avulsed from the spinal cord. In so called central avulsion injuries, the spinal root is avulsed at the interface between the central and peripheral nervous system (CNS and PNS).  This results not only in the disconnection of the root from the cord but also in a longitudinal spinal cord injury. The complexity of the injury leads to degeneration of the spinal root and a marked inflammatory response of the spinal cord followed by the formation of a glial scar. The study provides the first evidence that sensory regeneration across the CNS-PNS interface through growth permissive gates formed by engrafted hNP spheres can be achieved also in dorsal root avulsion. The mechanism behind the formation of growth permissive gates remains elusive and topographically specific regeneration will most likely require combinatorial approaches that are able to guide sensory axons after entering the spinal cord.