Shock wave application to rat skin induces degeneration and reinnervation of sensory nerve fibres

There have been several reports on the use of extracorporeal shock waves in the treatment of pseudarthrosis, calcifying tendinitis, and tendinopathies of the elbow. However, the pathomechanism of pain relief has not been clar ified. To investigate the analgesic properties of shock wave application, w e analyzed whether it produces morphologic changes in cutaneous nerve fibre s. In normal rat skin, the epidermis is heavily innervated by nerve fibres immunoreactive for protein gene product (PGP) 9.5 and by some fibres immuno reactive for calcitonin gene-related peptide (CGRP). There was nearly compl ete degeneration of epidermal nerve fibres in the shock wave-treated skin, as indicated by the loss of immunoreactivity for PGP 9.5 or CGRP. Reinnerva tion of the epidermis occurred 2 weeks after treatment. These data show tha t relief of pain after shock wave application to the skin results from rapi d degeneration of the intracutaneous nerve fibres. (C) 2001 Elsevier Scienc e Ireland Ltd. All rights reserved.