Estimation of Motor Nerve Conduction Velocity Distribution: A Frequency Domain Approach

Estimation of motor nerve conduction velocity distribution (NCVD) from the compound muscle action potential (CMAP) is a challenging problem for a long period, which would be a useful tool for evaluating the peripheral neuropathies by assessing the electrophysiological characteristics of the peripheral nerves. In the present study, we have analyzed the CMAP of ulnar nerves from the human subjects in the frequency domain. In this regard, we have expressed the collected CMAP as a circular convolution of the motor unit action potential (MUAP) and their associated delay sequence. The frequency domain analysis of the collected two CMAP's having different stimulating-recording distances helped us separate the delay sequence without even using any prior MUAP model. Finally, we have exploited the derived delay sequence to estimate the motor NCVD of ulnar nerve. Furthermore, we have estimated the derived MUAP using the frequency domain analysis. Our derived results conformed well to the previous NCVD studies and the histology results as well. The applied technique would be a helpful tool as it is non-invasive and offers a direct way to estimate the motor NCVD from the CMAP's.