Modifications d'excitabilité neuromusculaire produites par une contraction volontaire prolongée et réponse à la mexilétine dans la myotonie congénitale

Translated title of the contribution: Neuromuscular excitability changes produced by sustained voluntary contraction and response to mexiletine in myotonia congenita

Federica Ginanneschi, Andrea Mignarri, Sabrina Lucchiari, Gianna Ulzi, Giacomo P. Comi, Alessandro Rossi, Maria Teresa Dotti

Research output: Contribution to journalArticlepeer-review

Abstract

Objective To investigate the cause of transient weakness in myotonia congenita (MC) and the mechanism of action of mexiletine in reducing weakness. Methods The changes in neuromuscular excitability produced by 1 min of maximal voluntary contractions (MVC) were measured on the amplitude of compound muscle action potentials (CMAP) in two patients with either recessive or dominant MC, compared to control values obtained in 20 healthy subjects. Measurements were performed again in MC patients after mexiletine therapy. Results Transient reduction in maximal CMAP amplitude lasting several minutes after MVC was evident in MC patients, whereas no change was observed in controls. Mexiletine efficiently reduced this transient CMAP depression in both patients. Discussion Transient CMAP depression following sustained MVC may represent the electrophysiological correlate of the weakness clinically experienced by the patients. In MC, the low chloride conductance could induce self-sustaining action potentials after MVC, determining progressive membrane depolarization and a loss of excitability of muscle fibers, thus resulting in transient paresis. Mexiletine may prevent conduction block due to excessive membrane depolarization, thus reducing the transient CMAP depression following sustained MVC.

Translated title of the contributionNeuromuscular excitability changes produced by sustained voluntary contraction and response to mexiletine in myotonia congenita
Original languageFrench
Pages (from-to)247-252
Number of pages6
JournalNeurophysiologie Clinique
Volume47
Issue number3
DOIs
Publication statusPublished - Jun 1 2017

Keywords

  • Chloride conductance
  • Myotonia
  • Natural activity
  • Sodium channel
  • Weakness

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Physiology (medical)

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