Pain in SCN4A Mutated P.A1156T muscle sodium channelopathy—a postal survey

: The p.A1156T mutation alters the function of the voltage‐gated sodium channel Nav1.4 on the muscle sarcolemma, causing a channelopathy without overt myotonia or periodic paralysis but with myalgic pain. Methods : A postal survey was conducted to assess the prevalence and characteristics of pain and related symptoms in individuals with the p.A1156T mutation. A specific questionnaire, intensity and interference subscales of the Brief Pain Inventory, pain drawing, Widespread Pain Index, quality of life (RAND‐36), and the Beck Depression Inventory were completed. Results : Twenty of 24 patients replied. Current pain was reported by 16 respondents; the other 4 had experienced pain previously. Most commonly, pain was widespread and exercise‐induced. The severity and the impact of pain on daily life were considerable, although varied. Discussion : This sodium channelopathy is another entity in the growing number of diseases causing widespread myalgic pain that resembles the pain seen in fibromyalgia syndrome. Muscle Nerve 57 : 1014–1017, 2018