<Li> The level of injury: After a nerve is repaired, the regenerating nerve endings must grow all the way to their target . For example, a nerve injured at the wrist that normally provides sensation to the thumb must grow to the end of the thumb in order to provide sensation . The return of function decreases with increased distance over which a nerve must grow . </Li> <P> Currently, autologous nerve grafting, or a nerve autograft, is known as the gold standard for clinical treatments used to repair large lesion gaps in the peripheral nervous system . It is important that nerves are not repaired under tension, which could otherwise happen if cut ends are reapproximated across a gap . Nerve segments are taken from another part of the body (the donor site) and inserted into the lesion to provide endoneurial tubes for axonal regeneration across the gap . However, this is not a perfect treatment; often the final outcome is only limited function recovery . Also, partial deinnervation is frequently experienced at the donor site, and multiple surgeries are required to harvest the tissue and implant it . </P> <P> When appropriate, a nearby donor may be used to supply innervation to lesioned nerves . Trauma to the donor can be minimized by utilizing a technique known as end - to - side repair . In this procedure, an epineurial window is created in the donor nerve and the proximal stump of the lesioned nerve is sutured over the window . Regenerating axons are redirected into the stump . Efficacy of this technique is partially dependent upon the degree of partial neurectomy performed on the donor, with increasing degrees of neurectomy giving rise to increasing axon regeneration within the lesioned nerve, but with the consequence of increasing deficit to the donor . </P> <P> Some evidence suggests that local delivery of soluble neurotrophic factors at the site of autologous nerve grafting may enhance axon regeneration within the graft and help expedite functional recovery of a paralyzed target . Other evidence suggests that gene - therapy induced expression of neurotrophic factors within the target muscle itself can also help enhance axon regeneration . Accelerating neuroregeneration and the reinnervation of a denervated target is critically important in order to reduce the possibility of permanent paralysis due to muscular atrophy . </P>

The peripheral nerves can regenerate unlike those nerves found in the central nervous system