Toe-to-finger transplantation: Nerve regeneration, functional transformation, and central perception

Toe-to-finger transplantation provides an opportunity to study how the recipient nerve regenerates into a body part that has similar structure but different function, and how the transplanted toe is perceived by patients. In previous studies, technical improvement and motor function recovery were stressed, while the evaluation of sensory return was usually inadequate or not quantified. In more recent studies, quantitative sensory tests and electrophysiological methods were used to obtain more precise evaluation of nerve regeneration of both large myelinated and small unmyelinated nerve fibers. In addition, functional transformation and perception of the transplanted toes were investigated. In general, nerve regeneration and function recovery of the transplanted toes were satisfactory but incomplete. When sensory and current perception, threshold status were considered, the transplanted tow was intermediate between normal finger and normal toe, but was closer to normal toe. Regenerations of both large myelinated and small unmyelinated nerve fibers appear to be similar in rate and extent. The majority of the patients perceived transplanted toes as their fingers immediately or within 6 months after toe transplantation. Therefore, toe-to- finger transplantation represents one aspect of restorative neurology and provides an opportunity to look into nerve regeneration as well as functional transformation and perception of the transplanted toes.