Motor Unit Number Estimation Of Facial Muscles Using The M Scan Fit Method.

INTRODUCTION M Scan-Fit, an automated method for motor unit number estimation (MUNE), was assessed in muscles innervated by the facial nerve. METHODS Healthy volunteers were recruited. M Scans were recorded twice from nasalis and depressor anguli oris (DAO) muscles, and then fitted to a probabilistic model. RESULTS Twenty-one subjects were evaluated, 38% female, mean age 34.71 years. The average number of MUs was 38.57 on both testing occasions (t ≤ 0.0001; p=1.0) for the nasalis. For the DAO, results were 20.62 MUs for the first and 23.48 for the second (t=-2.12; p=0.04). Pearson's inter-rater correlation coefficients were 0.89 (p<0.0001) for nasalis and 0.56 (p=0.04) for the DAO. Intra-class correlation coefficients were 0.81 (p=0.016) for the nasalis and 0.37 (p=0.37) for the DAO. DISCUSSION M Scan-Fit MUNE is an automated, accurate, reliable method of estimating MU number and size from facial muscles. This article is protected by copyright. All rights reserved.