Abstract
Purpose of review: Unlike the central nervous system, the peripheral nervous system retains the ability to regenerate. However, complete functional recovery does not occur in most cases. For nerve defects of less than 3 cm, autografting or reverse autovein grafting is currently used. However, because these methods may produce limited functional recovery, recent research has focused on finding improved methods of repair. Recent findings: The primary areas of interest include axonal guidance channels, end-to-side, laser welding, and fibrin glue anastomosis, and various proregenerative drugs and trophic factors. Furthermore, there is a growing body of evidence suggesting that the immune system plays a positive role in regeneration. Nerves treated with predegenerated nerve segment extracts exhibit improved regeneration, and macrophage activation has been shown to enhance regeneration of retinal ganglion cells in vivo. This suggests that macrophages produce proregenerative factors that play a key role in peripheral nerve regeneration. Another region of budding interest is chronic nerve compression injury. Recent work has shown that chronic nerve compression injury does not induce immediate axonal pathology and may in fact be a Schwann cell-mediated disease. Chronic nerve compression injury induces both Schwann cell proliferation and apoptosis before axonal degeneration. Altered patterns of macrophage recruitment and myelination after chronic nerve compression injury also help to differentiate this injury from Wallerian degeneration. Summary: The recent increased interest in the basic science of peripheral nerve injury and regeneration will increase the likelihood that effective functional reinnervation may occur after injury. © 2004 Lippincott Williams & Wilkins.