Drive and explore! The preliminary results of using modified toy cars to improve mobility and socialization in toddlers with disabilities

Abstract

(MUNIX) is a novel electromyographic method for assessing the number and size of motor unit. The MUNIX value is derived from mathematical calculations based on the area and power of the compoundmuscle action potential (CMAP) recorded by surface electromyography. However, application of supra-maximal electrical stimulation technique under the standardmotor nerve conduction test procedure has its disadvantages of implementation such as discomfort. Transcranial magnetic stimulation (TMS) has been suggested as an alternative method to induce supra-maximal stimulation. It has the advantages of less painful and easy to perform. Purpose: To investigate the intra-rater reliability of MUNIX and MUSIX in healthy young adults by using TMS as a stimulator to produce supra-maximal stimulation. Methods: Surface EMG signals were recorded by using electrodes on abductor digiti minimi (ADM) of dominant hand. The EMG signals were amplified (330), band-filtered (1–5000Hz), and sampled at 2000Hz. The CMAP and surface electromyographic interference pattern (SIP) were recordedby standardmotor nerve conduction techniqueswith TMS as a stimulator to ulnar nerve. The negative phase of its amplitude, area, and power ofCMAPwas calculated. The SIP epoch was recorded for 300ms long with subjects instructed to exert and maintain an isometric contraction at varying levels of effort. Then its area, and powerwere computed. Finally, the MUNIX andMUSIX were computed according to Nandedker’smodel. The two tests were performedwithin 3–7 days by the same examiner. Results:Twenty two healthy young adults voluntarily participated in this study (11male, age 20.27± 0.47 years; 11 female, age 20.18± 0.40 years). The intra-class correlation coefficient (ICC) for MUNIX and MUSIX were 0.43 and 0.59, respectively. Conclusion(s): MUNIX and MUSIX measurements in ADM by TMS showed moderate intra-rater reliability in healthy young adults. Implications: Results suggest that MUNIX and MUSIX measurement could serve as a reliable method for motor unit number and size estimation when using TMS as a stimulator.