İnvestigation of the alterations in motor units in neurologic disorders by scanning electromyography

Abstract

In this study, the alterations in the length of cross-sections of MU and the changes in maximum amplitude of MUAPs in each MU in patients with JME were investigated. An experimental setup of scanning EMG was built and 3-D cross sectional maps of the MUs were plotted in order to measure the length of cross-sections and to find the maximum amplitude of each MU. Three subject groups comprising nine patients with juvenile myoclonic epilepsy as JME group, ten healthy volunteers as normal control (NC) group and three patients with spinal muscular atrophy as SMA group were included. The age of the subjects ranged between 22 and 46. Five to eight measurements were performed from the biceps brachialis muscles of each subject. Data including 113 measurements in total acquired from with these measurements were stored in a computer and then were used to construct 3-D maps of MU territories. All three groups were compared in pairs by using 113 measurements with Student’s t-test. JME groups were found similar to SMA group in terms of both parameters. The difference between JME and NC groups was found as extremely significant. Since the increase in both parameters due to the reinnervation occurs in SMA group, significant difference is expected between SMA and NC group. These results were confirmed with Tukey’s HSD test by comparing three groups simultaneously. Three groups were also compared using the individual means of parameters with a non-parametric test such as Mann-Whitney test. A significant difference which is also confirmed again with Tukey’s HSD test was found between the JME and NC groups. In conclusion, since no neurogenic evidence was found in JME patients in conventional EMG previously higher length of cross-sections can be considered as structural.|Keywords: Scanning EMG, Juvenile Myoclonic Epilepsy, Motor Unit Territory, Electrophysiological Cross-section.