Beyond the muscular involvement in non-dystrophic myotonias: The emerging role of neuromodulation

Article type: Research Article

Authors: Portaro, Simona^{a; 1} | Naro, Antonino^{a; 1} | Bramanti, Alessia^b | Leo, Antonino^a | Manuli, Alfredo^a | Balletta, Tina^a | Trinchera, Antonia^a | Bramanti, Placido^a | Calabrò, Rocco Salvatore^{a; *}

Affiliations: [a] IRCSS Centro Neurolesi Bonino Pulejo, Messina, Italy | [b] Institute of Applied Sciences and Intelligent Systems “Edoardo Caianello” (ISASI), National Research Council of Italy, Messina, Italy

Correspondence: [*] Corresponding author: Rocco Salvatore Calabrò; IRCCS Centro Neurolesi “Bonino– Pulejo”; S.S. 113, Contrada Casazza, 98124, Messina, Italy. Tel.: +3909060128954; Fax: +3909060128950; E-mail: salbro77@tiscali.it.

Note: [1] These authors equally contributed to the study.

Abstract: 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.

Keywords: Non-dystrophic myotonias (NDMs), central nervous system, rTMS, cortical excitability, sensory-motor plasticity, mexiletine

DOI: 10.3233/RNN-170796

Journal: Restorative Neurology and Neuroscience, vol. 36, no. 4, pp. 459-467, 2018