Isometric skeletal muscle force measurement in primary myopathies.
In myopathy patients, it is useful to measure skeletal muscle forces. Conventional methods require voluntary muscle activation, which can be unreliable. We evaluated a device for nonvoluntary force assessment.



We tested 8 patients (unknown myopathy n = 2, inflammatory myopathy, facioscapulohumeral muscular dystrophy, mitochondrial myopathy, dysferlinopathy, multi-minicore disease, Becker-Kiener muscular dystrophy, n = 1 each). Isometric twitch torques of ankle dorsiflexors were measured after fibular nerve stimulation.



Six patients had decreased torques vs. 8 controls (men: median Newton-meter 1.6 vs. 5.7, women: 0.2 vs. 3.9, both P < 0.0001). Values correlated with Manual Muscle Test results (r = 0.73; r(2) = 0.53; P < 0.0001). In weak dorsiflexors, torque could be measured despite lower signal-to-noise ratios. In 2 patients with hypertrophy, we measured increased torques.



Nonvoluntary muscle force assessment can be used in patients with myopathies, and values correlate with voluntary forces determined by traditional methods. Muscle Nerve 53: 913-917, 2016.
Department of Anesthesia and Biomedicine, University Hospital, Basel, Switzerland.
Hans F
HF
Ginz
Department of Surgery, Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota, USA.
Paul A
PA
Iaizzo
FMH Neurology, REHAB Basel AG, Basel, Switzerland.
Kathi
K
Schweikert
Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
William K
WK
Durfee
D000328:Adult; D000843:Ankle Joint / Q000294:innervation; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009135:Muscular Diseases / Q000473:pathology* / Q000503:physiopathology*; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D013557:Switzerland; D019415:Torque
distal myopathy; isometric contraction; muscle; skeletal; strength