Intraexaminer Variability of Nerve Conduction Study in Healthy Person

ABSTRACT

BACKGROUND: Nerve conduction study (NCS) is an objective and quantitative test in evaluating peripheral nerve disorders. Several physiological and technical factors are well known to influence the results of NCS, which can be controlled and regulated by standardization of environment and through the process to make range of normality. However, most electromyographers do not pay much attentions about inter- and intra-examiner variabilities, and there are only a few and incomplete reports on these topics. We examined the intra-examiner variability of NCS on the basis of periods of practice. METHODS: Twenty-eight electromyographers were divided into two groups residents and neurologist-technicians. All, having variable NCS training periods, have performed NCS on one of other 27 electromyographers ten times within two weeks where each study was made once a day. RESULTS: Coefficient of variation and external quotient increased according to the following order - nerve conduction velocities (NCV), terminal latencies (TL), and amplitudes of compound action potentials (AMP). There were significant differences between the two groups in NCV and TL, but no statistical difference in AMP. CONCLUSIONS: Our results suggest that errors from intra-examiner variability should be considered when interpreting NCS and that those electromyographers who have enough training should perform NCS.