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Neuromuscul Disord. 2016 Jan;26(1):60-72. doi: 10.1016/j.nmd.2015.09.013. Epub 2015 Sep 25.

Electromechanical delay components during skeletal muscle contraction and relaxation in patients with myotonic dystrophy type 1.

Author information

1
Department of Biomedical Sciences for Health, University of Milan, Via Colombo 71, 20133 Milan, Italy. Electronic address: fabio.esposito@unimi.it.
2
Department of Biomedical Sciences for Health, University of Milan, Via Colombo 71, 20133 Milan, Italy.
3
Department of Biomedical Sciences for Health, University of Milan, Via Colombo 71, 20133 Milan, Italy; IRCCS Policlinico San Donato, Piazza Malan 2, 20097 San Donato, Milanese (MI), Italy.
4
IRCCS Policlinico San Donato, Piazza Malan 2, 20097 San Donato, Milanese (MI), Italy.

Abstract

The electromechanical delay during muscle contraction and relaxation can be partitioned into mainly electrochemical and mainly mechanical components by an EMG, mechanomyographic, and force combined approach. Component duration and measurement reliability were investigated during contraction and relaxation in a group of patients with myotonic dystrophy type 1 (DM1, n = 13) and in healthy controls (n = 13). EMG, mechanomyogram, and force were recorded in DM1 and in age- and body-matched controls from tibialis anterior (distal muscle) and vastus lateralis (proximal muscle) muscles during maximum voluntary and electrically-evoked isometric contractions. The electrochemical and mechanical components of the electromechanical delay during muscle contraction and relaxation were calculated off-line. Maximum strength was significantly lower in DM1 than in controls under both experimental conditions. All electrochemical and mechanical components were significantly longer in DM1 in both muscles. Measurement reliability was very high in both DM1 and controls. The high reliability of the measurements and the differences between DM1 patients and controls suggest that the EMG, mechanomyographic, and force combined approach could be utilized as a valid tool to assess the level of neuromuscular dysfunction in this pathology, and to follow the efficacy of pharmacological or non-pharmacological interventions.

KEYWORDS:

Electromyogram; Latency; MMG; Mechanomyogram; Muscle weakness; Myotonia

PMID:
26520850
DOI:
10.1016/j.nmd.2015.09.013
[Indexed for MEDLINE]
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