Reproducibility of the CMAP scan

Introduction: The CMAP scan is a surface EMG method based on the successive activation of motor units. It provides information about reinnervation processes, the number of functional motor units and nerve excitability. The CMAP scan has potential value as a follow-up tool in monitoring disease progression, recovery or aging of the peripheral nerves. In this study, we assessed its interobserver and different day reproducibility. Methods: Two investigators recorded CMAP scans in ten healthy subjects, each on two different days. Intraclass correlation coefficients (ICCs) and coefficients of variation (CoVs) were calculated for the parameters extracted from the CMAP scan. Results: All CMAP scan parameters had a good different day (ICCs > 0.8 and CoVs < 15%) and interobserver reproducibility (ICCs > 0.7 and CoVs <= 15%). Different-day reproducibility was better than interobserver reproducibility. Conclusion: CMAP scan test-retest variability is small, suggesting that as a follow-up tool it may be sensitive to fairly small (patho) physiological changes in the studied variables. (C) 2010 Elsevier Ltd. All rights reserved.