Regenerative effects of pulsed magnetic field on injured peripheral nerves.

Previous studies confirm that pulsed magnetic field (PMF) accelerates functional recovery after a nerve crush lesion. The contention that PMF enhances the regeneration is still controversial, however. The influence of a new PMF application protocol (trained PMF) on nerve regeneration was studied in a model of crush injury of the sciatic nerve of rats. To determine if exposure to PMF influences regeneration, we used electrophysiological recordings and ultrastructural examinations. After the measurements of conduction velocity, the sucrose-gap method was used to record compound action potentials (CAPs) from sciatic nerves. PMF treatment during the 38 days following the crush injury enhanced the regeneration. Although the axonal ultrastructures were generally normal, slight to moderate myelin sheath degeneration was noted at the lesion site. PMF application for 38 days accelerated nerve conduction velocity, increased CAP amplitude and decreased the time to peak of the CAP. Furthermore, corrective effects of PMF on. the abnormal characteristics of sensory nerve fibers were determined. Consequently, long-periodic trained-PMF may promote both morphological and electrophysiological properties of the injured nerves. In addition, corrective effects of PMF on sensory fibers may be considered an important finding for neuropathic pain therapy.