Sensory re-education after nerve repair: aspects of timing.

The recovery of functional sensibility after nerve transection and repair is often disappointing. Here we address the timing of sensory re-education that aims at re-learning and modulating the changed sensory code from the hand after such an injury. Such training utilises the capacity for cortical functional re-modelling which characterises the young as well as the adult brain. Sensory re-education is traditionally not introduced until there is reinnervation in the hand, and such a late onset of training may be one explanatory factor for the poor functional results after nerve repair. Since functional reorganisation changes of the cortex occurring after changes in peripheral input are very fast processes, we suggest that this specific intervention should be introduced very early in the rehabilitation phase--already in the initial phase after nerve repair when no axons have yet arrived to the asensible hand. The goal is to avoid, minimise and modulate the central functional re-organisation which follows the de-afferentiation associated with nerve injury and repair. This early intervention can be done with the use of artificial sensibility the first post-operative day. According to this technique, based on sense substitution and utilising the multimodal capacity of the brain, miniature microphones on the fingertips of the asensible hand pick up the friction sound generated by active touch. The vibro-tactile signals are stereophonically transposed to vibro-acoustic signals, thereby providing an alternate feed-back which hypothetically helps to maintain or re-establish the cortical hand map.