Age‐related changes in motor unit number estimates in adult patients with Charcot–Marie–Tooth type 1A |
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Authors: | J P Van Dijk C Verhamme I N Van Schaik H J Schelhaas E Mans L J Bour D F Stegeman M J Zwarts |
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Institution: | 1. Department of Neurology/Clinical Neurophysiology, Radboud University Nijmegen Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Nijmegen;2. Department of Neurology and Clinical Neurophysiology, Academic Medical Centre, University of Amsterdam, Amsterdam;3. Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands |
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Abstract: | Background: Charcot–Marie–Tooth disease type 1A (CMT1A) is known as a demyelinating hereditary neuropathy. Secondary axonal dysfunction is the most important determinant of disease severity. In adult patients, clinical progression may be because of further axonal deterioration as was shown with compound muscle action potential (CMAP) amplitude reductions over time. The motor unit number estimation (MUNE) technique may be more accurate to determine the number of axons as it is not disturbed by the effect of reinnervation. The purpose of this study was to investigate the number and size of motor units in relation to age in patients and controls. Methods: In a cross‐sectional design, we assessed arm and hand strength and performed electrophysiological examinations, including CMAP amplitudes and MUNE of the thenar muscles using high‐density surface EMG in 69 adult patients with CMT1A and 55 age‐matched healthy controls. Results: In patients, lower CMAP amplitudes and MUNE values were related to hand weakness. The CMAP amplitude and MUNE value of the thenar muscles were significantly lower in patients than in controls. CMAP amplitudes declined with age in controls, but not in patients. MUNE values declined with age in both patients and controls. Conclusions: The age‐dependent decrease in the number of motor units was not significantly different between patients with CMT1A and controls, indicating that loss of motor units in adult patients is limited. |
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Keywords: | axonal dysfunction Charcot– Marie– Tooth disease CMT1A compound muscle action potential hereditary motor and sensory neuropathies hereditary motor and sensory neuropathy Ia high‐density surface EMG motor unit number estimation |
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