New directions in peripheral nerve surgery.

The current philosophy of the microneurosurgical management of nerve injury is reviewed. Controversial techniques such as internal neurolysis are discussed as is the surgical dilemma of the neuroma incontinuity. Nerve regeneration is under the mechanical influence of contract guidance and the neurobiological influence of neurotropism and neurotrophism, or, as we have coined it, neurotrop(h)ism. The concepts of neurotrop(h)ism and contact guidance are discussed, emphasizing the potential importance of neurobiology in determining functional outcome following nerve repair. Finally, the interaction of the immune system and nerve regeneration is discussed.