BACKGROUND: The central nervous system involvement, in terms of a maladaptive sensory-motor plasticity, is well known in patients with dystrophic myotonias (DMs). To date, there are no data suggesting a central nervous system involvement in non-dystrophic myotonias (NDMs).
OBJECTIVE: To investigate sensory-motor plasticity in patients with Myotonia Congenita (MC) and Paramyotonia Congenita (PMC) with or without mexiletine.
METHODS: Twelve patients with a clinical, genetic, and electromyographic evidence of MC, fifteen with PMC, and 25 healthy controls (HC) were included in the study. TMS on both primary motor cortices (M1) and a rapid paired associative stimulation (rPAS) paradigm were carried out to assess M1 excitability and sensory-motor plasticity.
RESULTS: patients showed a higher cortical excitability and a deterioration of the topographic specificity of rPAS aftereffects, as compared to HCs. There was no correlation among neurophysiological and clinical-demographic characteristics. Noteworthy, the patients who were under mexiletine showed a minor impairment of the topographic specificity of rPAS aftereffects as compared to those who did not take the drug.
CONCLUSION: our findings could suggest the deterioration of cortical sensory-motor plasticity in patients with NDMs as a trait of the disease.
- Analysis of Variance
- Anti-Arrhythmia Agents/therapeutic use
- Evoked Potentials, Motor/drug effects
- Follow-Up Studies
- Mexiletine/therapeutic use
- Motor Cortex/physiology
- Myotonia Congenita/drug therapy
- Myotonic Disorders/physiopathology
- Neuronal Plasticity/physiology
- Transcranial Magnetic Stimulation
- Young Adult