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 Pecker'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 vo ltage gated Cl- channel protein in the muscle membrane of these patients is unclear. In order to gain a better understanding of the electrophysiologic al properties of the muscle fibre membrane in these generalized myotonia pa tients, 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 transien t paresis shows a decrease in peak-peak amplitude of the motor unit action potentials from endplate towards tendon, This disturbance increases with ti me and place, indicating a deteriorating membrane function, and ends in a c omplete blocking of propagation within seconds. Spatiotemporally, this lead s to a V-shaped sEMG pattern, In a more general sense, this contribution sh ows how spatiotemporal information, available through non-invasive high-den sity sERMG, may provide novel insights into electrophysiological aspects of membrane dysfunction.