Bridging the Neural Gap

Although the future of nerve surgery holds exciting possibilities, the current reality is that the results of nerve repair have not significantly improved over the past several decades. The initial principles set forth by Sir Sidney Sunderland during World War II still hold true. A major limitation to overall success in peripheral nerve surgery is time for regeneration. This principle remains true regardless of the technique used for the repair. Without prompt motor nerve input, denervated muscle becomes resistant to nerve regeneration. Although one can help speed up the regenerative process to some extent, success is hindered by additional issues, such as number of coaptation sites, supply of donor nerves, and the limitations of nerve substitutes. At every coaptation site, a percentage of nerve fibers are lost. Excessive tension is harmful to a repair site, and, in the case of a large gap, a nerve graft is often used to fill in the deficit. Autogenous nerve grafts are in limited supply, with sural nerve grafts being the primary source. Alternatives to the standard treatment include vein grafts, synthetic nerve conduits, nerve transfers, and nerve transplantation. Schwann cell– lined nerve conduits and tissue-engineered substitutions are still in their infancy and have some limited clinical application.