Propagation disturbance of motor unit action potentials during transient paresis in generalized myotonia: a high-density surface EMG study.
Patients with autosomal recessive generalized myotonia, or Becker's disease, often suffer from a peculiar transient paresis. As yet, the relationship between this transient paresis and the defect in the gene encoding for a voltage gated Cl- channel protein in the muscle membrane of these patients is unclear. In order to gain a better understanding of the electrophysiological properties of the muscle fibre membrane in these generalized myotonia patients, we have studied transient paresis with a novel high-density surface EMG (sEMG) technique. We conclude that the transient paresis is explained by a deteriorating muscle membrane function, ending in conduction block and paresis. Multi-channel sEMG during the period of force decline in transient paresis shows a decrease in peak-peak amplitude of the motor unit action potentials from endplate towards tendon. This disturbance increases with time and place, indicating a deteriorating membrane function, and ends in a complete blocking of propagation within seconds. Spatiotemporally, this leads to a V-shaped sEMG pattern. In a more general sense, this contribution shows how spatiotemporal information, available through non-invasive high-density sEMG, may provide novel insights into electrophysiological aspects of membrane dysfunction.
Drost
G
G
Department of Clinical Neurophysiology, University Medical Centre, Nijmegen, The Netherlands.
Blok
J H
JH
Stegeman
D F
DF
van Dijk
J P
JP
van Engelen
B G
BG
Zwarts
M J
MJ
D000200:Action Potentials; D000328:Adult; D004576:Electromyography / Q000295:instrumentation* / Q000379:methods; D005260:Female; D005808:Genes, Recessive; D006801:Humans; D008297:Male; D008875:Middle Aged; D009045:Motor Endplate / Q000503:physiopathology; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal; D009224:Myotonia Congenita / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D010291:Paresis / Q000209:etiology / Q000503:physiopathology*; D013314:Stress, Mechanical