Restorative Neurology and Neuroscience - Volume 26, issue 2-3

Authors: Nógrádi, Antal | Szabó, András

Article Type: Research Article

Abstract: Loss of spinal motoneurones results in severe functional impairment. The most successful way to replace missing motoneurones is the use of embryonic postmitotic motoneurone grafts. It has been shown that grafted motoneurones survive, differentiate and integrate into the host cord. If grafted motoneurones are provided with a suitable conduit for axonal regeneration (e.g. a reimplanted ventral root) the grafted cells are able to grow their axons along the whole length of the peripheral nerves to reach …muscles in the limb and restore function. Grafted motoneurones show excellent survival in motoneurone-depleted adult host cords, but the developing spinal cord appears to be an unfavourable environment for these cells. The long term survival and maturation of the grafted neurones are dependent on the availability of a nerve conduit and one or more target muscles, no matter whether these are ectopic nerve-muscle implants or limb muscles in their original place. Thus, grafted and host motoneurones induce functional recovery of the denervated limb muscles when their axons regenerate into an avulsed and reimplanted ventral root. On the other hand, motoneurone-enriched embryonic grafts placed into a hemisection cavity in the cervical spinal cord induce axonal regeneration from great numbers of host motoneurones, possibly by the bridging effect of the grafts. In this case the regenerating host motoneurones reinnervate their original target muscles while the graft provides few axons for the reinnervation of muscles. These results suggest that reconstruction of the injured spinal cord with embryonic motoneurone-enriched spinal cord graft is a feasible method to improve severe functional motor deficits. Show more

Keywords: Motoneurone, spinal cord, spinal injury, skeletal muscle, ventral root, reinnervation, ALS

Citation: Restorative Neurology and Neuroscience, vol. 26, no. 2-3, pp. 215-223, 2008

Authors: Carlstedt, Thomas

Article Type: Research Article

Abstract: Spinal nerve root injuries have a profound effect on the different parts (PNS and CNS) of the root itself as well as the pertinent spinal cord segment. A root avulsion from the spinal cord is a longitudinal spinal cord injury. There is degeneration of sensory and motor axons, loss of synapses, deterioration of local segmental connections, nerve cell death and reactions among non neuronal cells with scar formation, i.e. a cascade of events similar to those …known to occur in any injury to the spinal cord. For function to be restored, nerve cells must survive and there must be regrowth of new nerve fibres along a trajectory consisting of CNS growth-inhibitory tissue in the spinal cord as well as PNS growth-promoting tissue in nerves. Problems in PNS regeneration such as non directional growths and unspecific reinnervation of target organs lead to unpredictable sensorimotor activity and conspires against a useful recovery of function. From the results of basic science experiments, a surgical strategy to treat root avulsion with spinal cord injury has been developed. In humans this technique is currently the most promising treatment of any spinal cord injury, with return of useful function together with pain alleviation in cases where all nerves to the extremity have been avulsed from the spinal cord. At present the shortcomings of this technique are proportionate to the delay before surgery, which leads to death of nerve cells and incomplete and unpredictable recovery. In order to improve this situation and achieve further recovery of useful function including sensory perceptions and to fully alleviate pain it is necessary to pursue research and development of both basic and clinical science. Show more

Keywords: Root injury, spinal cord implantation, sensimotor recovery, pain, plasticity

Citation: Restorative Neurology and Neuroscience, vol. 26, no. 2-3, pp. 225-241, 2008