The paramyotonia congenita belongs to non-dystrophic myotonic syndromes. It is characterized by myotonia which paradoxically worsens during exercise and which can, if necessary, be disabling, especially in cold weather conditions. In the very large majority of cases, it is related to dominant mutations in the SNC4A gene encoding a voltage-gated sodium channel. Treatment remains symptomatic and patients are often improved by daily intake of mexiletine (now marketed in France under the name Namuscla®) or, more rarely, lamotrigine.
Italian clinicians, interested in the problems of contraindications or poor tolerance, especially cardiac and digestive, of these preferred treatments, report, in an article published in April 2021, their experience with buprenorphine, a well-known standard substitute in the withdrawal of opioid addiction and having properties of blocking the sodium channel involved. Evaluated in two adult patients refractory to other treatments and administered at a rate of one 0.5 mg tablet twice a day, the treatment was very conclusive both clinically and electrophysiologically, at four weeks apart. The authors nevertheless point the risk of addiction to this type of medication and the need to test it on a larger sample of patients.