The response to injury in the perihperal nervous system

Persisting neurones switch to a ‘survivor’ phenotype and the expression of hundreds of genes^8,9 is changed to compensate for the loss or diminution of target-derived neurotrophic factors,¹⁰ and in order to regrow their axons across the site of the injury and back into the periphery. Proximal changes, such as synaptic reorganisation in the cortex^11–13 and spinal cord, occur upstream of axotomised first-order motor and sensory neurones, and may influence the functional outcome months or even years later.^14–16 Distal to the injury, a series of molecular and cellular events, some simultaneous, others consecutive, and collectively called Wallerian degeneration, is triggered throughout the distal nerve stump and within a small reactive zone at the tip of the proximal stump (Fig. 2).^17–19

http://web.jbjs.org.uk/cgi/content/full/87-B/10/1309