重症肌无力误诊一例

Misdiagnosis of myasthenia gravis: a case report

重症肌无力是一种神经-肌肉接头传递功能障碍性疾病,主要临床特征为受累骨骼肌易疲劳,休息后减轻,晨轻暮重。该病多隐袭起病,眼外肌最先受累。该文报道1例胸腺瘤所致的重症肌无力患者,其虽有眼外肌最先受累的表现,但为急性起病,且有不洁饮食史,无晨轻暮重现象,故曾被误诊为吉兰-巴雷综合征、肉毒杆菌中毒。经检测,其乙酰胆碱受体抗体阳性,重频神经电刺激低频电刺激波幅有明显递减现象,高频未见递增递减现象,新斯的明试验阳性,胸腺CT提示为胸腺瘤。其后于胸腔镜下行胸腺瘤摘除术,术后病理学检查示B3型胸腺瘤,最终明确诊断为胸腺瘤所致的重症肌无力。术后患者恢复良好。因此,对于出现周围神经特别是颅神经支配区受累症状的患者,应考虑到肌肉疾病、神经-肌肉接头疾病的可能。

Myasthenia gravis is a disease of neuro-muscular dysfunction. Main clinical characteristics include the fatigue of affected skeletal muscle, which can be relieved after resting. The symptom is slight in the morning and becomes aggravated in the evening. The onset of myasthenia gravis is elusive and extraocular muscle is the predisposing affected muscle. Here we reported one case of myasthenia gravis caused by thymoma.Although extraocular muscular involvement was the initial presentation, the patient presented with acute episode and had a history of eating contaminated food, whereas had no phenomenon of slight symptom in the morning and severe in the evening. The patient was misdiagnosed as Guillain-Barre syndrome and botulism infection.The acetylcholine receptor antibody was detected positive. The low-frequency rather electrical stimulation amplitudeof heavy-frequency nerve electrical stimulation was declined, whereas no decrease was detected in highfrequencyelectrical stimulation amplitude. Neostigmine test yielded positive results. Thymus CT hinted the signof thymoma, which was surgically resected under thoracoscope. Postoperative pathological examination demonstratedthe type of B3 thymoma. Finally, the patient was diagnosed with myasthenia gravis caused by thymoma.The patient recovered well after surgery. Therefore, the possibility of muscular and neuro-muscular diseases should be considered for patients with peripheral nerve symptoms, especially those involved with cranial nerve innervation region.