Evaluation of periodic electrodiagnostic measurements to monitor motor recovery after different peripheral nerve lesions in the rat.

INTRODUCTION: The advantage of minimally invasive electrodiagnostic methods for periodic evaluation of reinnervation at predefined time intervals does not seem to be widely recognized. In this study, using a rat model, we assessed the utility of periodic electrodiagnostic measurements for monitoring ongoing motor recovery after peripheral nerve injuries of differing severity.
METHODS: In a comparative study, either unilateral sciatic nerve crush injury (n = 10), end-to-end coaptation (n = 5), or 10-mm nerve autotransplantation (n = 10) were performed. During the 6-16-week period thereafter compound muscle action potentials (CMAPs) were recorded percutaneously every week in anesthetized animals. Motor nerve conduction velocity and percentage of axon loss were calculated and compared with footprint analyses (static sciatic index, SSI) and evaluations of sensory recovery.
RESULTS: Our results clearly demonstrate that, although SSI measurements reliably demonstrated progress of regeneration after nerve crush injury only, differences in electrodiagnostically determined values precisely remodeled differences in axonal regeneration, which was confirmed by histomorphometric analysis of axonal regeneration.
CONCLUSIONS: Percutaneous electrodiagnostic measurements enable reliable estimation of axonal regeneration parameters such as myelination and nerve fiber density and display in close proximity the actual status of axonal regeneration.