Maggi Lorenzo, Brugnoni Raffaella, Canioni Eleonora, Maccagnano Elio, Bernasconi Pia, Morandi Lucia
Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico "Carlo Besta", Milan, Italy;
Neuroradiology Department, Fondazione IRCCS Istituto Neurologico "Carlo Besta", Milan, Italy.
Acta Myol. 2015 Dec;34(2-3):109-15.
Skeletal muscle channelopathies (SMC), including non dystrophic myotonias (NDM) and periodic paralyses (PP), are characterized by considerable clinical overlap and clinical features not always allow addressing molecular diagnosis. Muscle imaging has been shown to be useful for differential diagnosis in neuromuscular disorders, however it has been relatively poorly investigated in SMC. We studied 15 patients affected by genetically confirmed SMC (NDM = 9, PP = 6) through muscle MRI or CT of thighs and legs, including 11 patients mutated in SCN4A gene, 2 in CACNA1S and 2 in CLCN1. Mean age at muscle imaging was 45.2 ± 18 years (range 22-70). Overall, fatty infiltration was found in thigh muscles in 8 (53%) patients and in leg muscles in 10 (60%). All patients mutated in CLCN1 and CACNA1S had abnormal thigh and/or leg muscle MRI, regardless the disease duration. On the contrary normal thigh and leg muscle MRI or CT scans were observed in 4/15 (27%) patients, all mutated in SCN4A. Variable degrees of fatty changes were found in patients mutated in SCN4A, CACNA1S and CLCN1. No differences on overall score of fatty infiltration were detected between NDM and PP (p-value = 0.953) neither between presence or absence of permanent weakness (p-value = 0.951). Our data confirm the presence of muscle fatty changes in the majority of SMC patients, although without any specific pattern of involvement. However muscle MRI may be a useful tool for longitudinal follow-up of SMC patients, in particular to evaluate the occurrence and the progression of fixed myopathy.
骨骼肌离子通道病（SMC），包括非营养不良性肌强直（NDM）和周期性瘫痪（PP），其特点是临床症状有相当大的重叠，临床特征并不总是有助于进行分子诊断。肌肉成像已被证明在神经肌肉疾病的鉴别诊断中有用，然而在SMC中对其研究相对较少。我们通过大腿和小腿的肌肉MRI或CT研究了15例经基因确诊的SMC患者（NDM = 9例，PP = 6例），其中11例患者SCN4A基因发生突变，2例患者CACNA1S基因发生突变，2例患者CLCN1基因发生突变。肌肉成像时的平均年龄为45.2±18岁（范围22 - 70岁）。总体而言，8例（53%）患者大腿肌肉存在脂肪浸润，10例（60%）患者小腿肌肉存在脂肪浸润。所有CLCN1和CACNA1S基因发生突变的患者大腿和/或小腿肌肉MRI均异常，与病程无关。相反，15例患者中有4例（27%）患者大腿和小腿肌肉MRI或CT扫描正常，这些患者均为SCN4A基因发生突变。在SCN4A、CACNA1S和CLCN1基因发生突变的患者中发现了不同程度的脂肪变化。NDM和PP之间在脂肪浸润总分上未检测到差异（p值 = 0.953），在有无永久性肌无力之间也未检测到差异（p值 = 0.951）。我们的数据证实大多数SMC患者存在肌肉脂肪变化，尽管没有任何特定的受累模式。然而，肌肉MRI可能是SMC患者纵向随访的有用工具，特别是用于评估固定性肌病的发生和进展。
