A Hybrid Classifier for Characterizing Motor Unit Action Potentials in Diagnosing Neuromuscular Disorders

Abstract

Background: The time and frequency features of motor unit action potentials (MUAPs) extracted from electromyographic (EMG) signal provide discriminative information for diagnosis and treatment of neuromuscular disorders. However, the results of conventional automatic diagnosis methods using MUAP features is not convincing yet. Objective: The main goal in designing a MUAP characterization system is obtaining high classifcation accuracy to be used in clinical decision system. For this aim, in this study, a robust classifer is proposed to improve MUAP classifcation performance in estimating the class label (myopathic, neuropathic and normal) of a given MUAP. Method: The proposed scheme employs both time and time–frequency features of a MUAP along with an ensemble of support vector machines (SVMs) classifers in hybrid serial/parallel architecture. Time domain features includes phase, turn, peak to peak amplitude, area, and duration of the MUAP. Time–frequency features are discrete wavelet transform coeffcients of the MUAP. Results: Evaluation results of the developed system using EMG signals of 23 subjects (7 with myopathic, 8 with neuropathic and 8 with no diseases) showed that the system estimated the class label of MUAPs extracted from these signals with average of accuracy of 91% which is at least 5% higher than the accuracy of two previously presented methods. Conclusion: Using different optimized subsets of features along with the presented hybrid classifer results in a classifcation accuracy that is encouraging to be used in clinical applications for MUAP characterization.

Keywords

• EMG
• Hybrid classifer design
• MUAP characterization
• Mutual information