PDF(Pubmed)
Abstract：
Congenital myotonia represents a rare group of genetically inherited conditions. It can be either autosomal dominant (Thomsen) or autosomal recessive (Becker). It is characterized by muscular hypertrophy, proximal weakness, and myotonia, or impaired relaxation after contraction. These are due to mutations in the CLC1 gene. A 14-year-old male child presented with complaints of gradually progressive weakness for five years. Weakness was more pronounced in the proximal muscle groups. The weakness worsened after rest and improved with activity. This led to absenteeism and affected his school performance. Clinical examination showed generalized muscular hypertrophy with pronounced hypertrophy of the calf muscles. A neurological examination showed significant myotonia and impaired relaxation after making a fist. The diagnosis of myotonia was confirmed by electromyography, which produced a dive-bomber sound on insertion. Next-generation sequencing revealed a homozygous eight-base pair insertion in exon 19 of the CLCN1 gene. This mutation has not been reported in the existing literature for myotonia congenita. The child was started on mexiletine and improved significantly. Presently, the patient is on regular medications and doing well on follow-up. Though rare, congenital myotonia is an important cause of neuromuscular weakness. It can be easily diagnosed with a thorough clinical examination and routine testing for myotonia in all children with weakness. The treatment is relatively simple and can give the patient significant relief. Myotonia can be easily diagnosed clinically, and pharmacotherapy and proper monitoring can remarkably improve patients\' quality of life.
摘要：
先天性肌强直是一组罕见的遗传遗传条件。它可以是常染色体显性遗传(Thomsen)或常染色体隐性遗传(Becker)。它的特点是肌肉肥大，近端无力,和肌强直，或收缩后松弛受损。这些是由于CLC1基因中的突变。一名14岁的男孩抱怨五年来逐渐虚弱。在近端肌肉群中，虚弱更为明显。弱点在休息后恶化，并随着活动而改善。这导致了旷工，并影响了他的学校表现。临床检查显示全身肌肉肥大，小腿肌肉明显肥大。神经系统检查显示拳头后明显的肌强直和放松障碍。肌电图证实了肌强直的诊断，插入时会发出俯冲轰炸机的声音。下一代测序揭示了CLCN1基因外显子19中的纯合八碱基对插入。在现有的先天性肌强直症文献中尚未报道这种突变。孩子开始服用美西律，并明显改善。目前,患者正在接受常规药物治疗，随访情况良好。虽然罕见，先天性肌强直是神经肌肉无力的重要原因。它可以很容易地诊断与一个彻底的临床检查和肌强直在所有儿童无力的常规测试。治疗相对简单，可以给患者带来明显的缓解。肌强直可以很容易地诊断为临床，药物治疗和适当的监测可以显著提高患者的生活质量。
