新英格兰NEJM：副肿瘤性神经性肌强直
一位70岁男性患有冠心病，慢性阻塞性肺疾病，40年吸烟史，2月来出现肌肉震颤和痉挛，汗多，并且体重减轻了10kg。体检发现肌纤维震颤（非自觉性肌肉颤搐，肌肉痉挛）和肌束震颤（可在此观看视频）。肌纤维震颤在睡觉时加重并持续存在。压缩肌肉后未见无力，强直，萎缩或者弛等现象。肌电力示特异性的神经性肌强直和肌纤维震颤放电特征。血清学检查示电压门控钾通道复杂抗体阳性（396pmol/l，正常值<85pmol/l）。根据临床表现，肌电力和血清学检查，诊断为神经性肌强直。这种强直是由于外周神经过度兴奋导致了肌纤维的激活。开始使用卡马西平治疗，但是症状控制不理想。可能是因为神经性肌强直可能是副肿瘤性的，患者有吸烟史和明显的体重减轻史，因此应该排除癌症的可能。锁骨上淋巴结活检显示小细胞肺癌。患者于3月后因化疗并发症而死亡。
A 70-year-old man with coronary artery disease, chronic obstructive pulmonary disease, and a 40-pack-year smoking history presented to a neurologist with a 2-month history of muscle twitching and spasms, excessive sweating, and a 10-kg weight loss. The physical examination revealed myokymia (involuntary, undulating muscle twitching) and fasciculations (see video). Myokymia worsened with exercise and persisted during sleep. There was no muscle weakness, rigidity, atrophy, or delayed muscle relaxation after contraction. Needle electromyography showed characteristic neuromyotonic and myokymic discharges. Serologic testing for antibodies against the voltage-gated potassium channel complex was positive (396 pmol per liter; normal value, <85). On the basis of clinical, electromyographic, and serologic findings, neuromyotonia was diagnosed. In this condition, hyperexcitability of peripheral-nerve axons results in continuous activation of muscle fibers. Treatment with carbamazepine was initiated but was ineffective in controlling the symptoms. Because neuromyotonia may be paraneoplastic, and given the patient’s smoking history and marked weight loss, diagnostic evaluation for cancer was performed. Ultimately, biopsy of an enlarged supraclavicular lymph node revealed metastatic small-cell lung cancer. The patient died 3 months later from complications of chemotherapy.
原文：http://www.nejm.org/doi/full/10.1056/NEJMicm1402098
Paraneoplastic Neuromyotonia
A 70-year-old man with coronary artery disease, chronic obstructive pulmonary disease, and a 40-pack-year smoking history presented to a neurologist with a 2-month history of muscle twitching and spasms, excessive sweating, and a 10-kg weight loss. The physical examination revealed myokymia (involuntary, undulating muscle twitching) and fasciculations (see video). Myokymia worsened with exercise and persisted during sleep. There was no muscle weakness, rigidity, atrophy, or delayed muscle relaxation after contraction. Needle electromyography showed characteristic neuromyotonic and myokymic discharges. Serologic testing for antibodies against the voltage-gated potassium channel complex was positive (396 pmol per liter; normal value, <85). On the basis of clinical, electromyographic, and serologic findings, neuromyotonia was diagnosed. In this condition, hyperexcitability of peripheral-nerve axons results in continuous activation of muscle fibers. Treatment with carbamazepine was initiated but was ineffective in controlling the symptoms. Because neuromyotonia may be paraneoplastic, and given the patient’s smoking history and marked weight loss, diagnostic evaluation for cancer was performed. Ultimately, biopsy of an enlarged supraclavicular lymph node revealed metastatic small-cell lung cancer. The patient died 3 months later from complications of chemotherapy.
原文：http://www.nejm.org/doi/full/10.1056/NEJMicm1402098
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