Estimating motor unit numbers from a CMAP scan: Repeatability study on three muscles at 15 centres

D M Sørensen, H Bostock, A Abrahao, A Alaamel, H C Alaydin, M Ballegaard, E Boran, B Cengiz, M de Carvalho, Ø Dunker, A Fuglsang-Frederiksen, C C Graffe, K E Jones, M Kallio, S Kalra, C Krarup, T Krøigård, R Liguori, T Lupescu, S MaitlandJ M Matamala, M Moldovan, J Moreno-Roco, K B Nilsen, L Phung, M O Santos, A C Themistocleous, H Uysal, V Vacchiano, R G Whittaker, L Zinman, H Tankisi*

*Corresponding author for this work


OBJECTIVE: To assess the repeatability and suitability for multicentre studies of MScanFit motor unit number estimation (MUNE), which involves modelling compound muscle action potential (CMAP) scans.

METHODS: Fifteen groups in 9 countries recorded CMAP scans twice, 1-2 weeks apart in healthy subjects from abductor pollicis brevis (APB), abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. The original MScanFit program (MScanFit-1) was compared with a revised version (MScanFit-2), designed to accommodate different muscles and recording conditions by setting the minimal motor unit size as a function of maximum CMAP.

RESULTS: Complete sets of 6 recordings were obtained from 148 subjects. CMAP amplitudes differed significantly between centres for all muscles, and the same was true for MScanFit-1 MUNE. With MScanFit-2, MUNE differed less between centres but remained significantly different for APB. Coefficients of variation between repeats were 18.0% for ADM, 16.8% for APB, and 12.1% for TA.

CONCLUSIONS: It is recommended for multicentre studies to use MScanFit-2 for analysis. TA provided the least variable MUNE values between subjects and the most repeatable within subjects.

SIGNIFICANCE: MScanFit was primarily devised to model the discontinuities in CMAP scans in patients and is less suitable for healthy subjects with smooth scans.

Original languageEnglish
JournalClinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology
Pages (from-to)92-99
Number of pages8
Publication statusE-pub ahead of print - 8 May 2023


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