Development of a new algorithm for the estimation of the step percentage in compound muscle action potential scan

Abstract

Compound Muscle Action Potential (CMAP) Scan used in the diagnosis and in the monitoring of Neuromuscular Diseases is based on recording the responses obtained from the gradual stimulation of a peripheral nerve. Clearly visible differences between CMAPs are referred as step. The maximum CMAP percentage of all detected steps are defined as Step Percentage and this is one of the parameters providing evidence for Motor Unit (MU) loss and for reinnervation. The aim of this study is to develop an algorithm which enables to estimate the step percentage more quantitatively. Motor neuron groups which were created through a simulator software were stimulated gradually. The step sizes were computed by utilizing the obtained responses as CMAPs in computing step sizes. Then, these step sizes were sorted in descending order. The step percentage was estimated by taking the cumulative sum of the values greater than two standard deviations (SD) of these sorted step sizes by running the aforementioned algorithm. It was seen that there are larger in fluctuations Step% values in motor neuron groups with lower number of axons, however, a more regular decreasing trend with smaller fluctuations was observed in higher number of axons. In the future studies, the inclusion of further motor neurons with greater axons numbers will be established. Moreover, the application of the algorithm for the patient data will be also considered. © 2019 IEEE.