Reproducibility of different nerve conduction velocity measurements in healthy test subjects and patients suffering from diabetic polyneuropathy.

According to literature, repeated nerve conduction velocity measurement may yield differences of up to 10 m/s in the same subject without any need to regard these differences as pathological. In order to get more details about the reproducibility of different nerve conduction velocity parameters, 59 healthy test subjects and 47 patients suffering from diabetic polyneuropathy were investigated. In the sural nerve latency prolongation after paired stimulation, conduction velocity and amplitude of nerve action potential were determined, in the peroneal nerve conduction velocity, distal latency, amplitude of nerve action potential after distal stimulation and F-wave. All investigations were performed using surface electrodes. Measurements were repeated within one day by the same investigator using exactly the same methods. No statistically significant differences between both investigations in test subjects and patients were found. Statistically, results for patients differed significantly from healthy test subjects. Six patients showed discrepancies between both measurements in the individual estimation normal/abnormal in comparison to laboratory norm values. In conclusion, these results demonstrate that strict adherence to technical and methodological parameters-including the same investigator-results in a higher improvement of reproducibility of nerve conduction velocity measurement. Multiple factors are operating in time but strict adherence to technical, methodological, physiological and biological parameters minimises changed results of neurophysiological measurements and improves reproducibility.