Background Lambert-Eaton myasthenic syndrome (LEMS) is a neuromuscular junction disorder and the clinical triad consists of proximal muscle weakness, autonomic symptoms and reduced tendon reflexes. Sluggish pupillary reflexes are common but dilated fixed pupils are rare. Case presentation We report a patient with a rare clinical course of LEMS. The patient was hospitalised due to progressive dyspnoea. She was ambulant and independent of oxygen at hospitalisation. The following day she suffered an in-hospital cardiac arrest based on hypoxia due to sputum stasis. The neurology department was consulted since the patient did not trigger on the ventilator after cessation of sedation. On neurological examination, the patient had dilated and fixed pupils, severe muscle weakness and areflexia, but a normal consciousness. Finally, she was diagnosed with LEMS. In this case report, the clinical course and diagnostic workup including anti-VGCC antibody testing, imaging and the results of electrophysiological studies are discussed. We also emphasise the importance of malignancy screening since the conventional chest CT was negative for lung carcinoma, but PET-CT raised a high suspicion for small-cell lung carcinoma. Conclusions A rare course of LEMS, with early respiratory failure and wide, fixed pupils. Regarding repetitive nerve stimulation, it is important to stimulate long enough to see the incremental response. Furthermore, this study illustrated the importance of malignancy screening with PET-CT when there is a high suspicion of small-cell lung carcinoma with negative conventional CT. Data are available on reasonable request.

中文翻译：

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固定瞳孔散大和呼吸衰竭：兰伯特-伊顿肌无力综合征的罕见临床病程

背景 兰伯特-伊顿肌无力综合征 (LEMS) 是一种神经肌肉接头疾病，临床三联征包括近端肌肉无力、自主神经症状和腱反射减弱。瞳孔反射迟缓很常见，但散大的固定瞳孔很少见。病例介绍 我们报告一名患有罕见 LEMS 临床病程的患者。该患者因进行性呼吸困难而住院。住院期间她可以行走且无需吸氧。第二天，她因痰瘀缺氧而在院内心脏骤停。由于患者在停止镇静后没有触发呼吸机，因此咨询了神经内科。神经系统检查显示，患者瞳孔散大、固定，严重肌无力和反射消失，但意识正常。最后，她被诊断出患有LEMS。在本病例报告中，讨论了临床病程和诊断检查，包括抗 VGCC 抗体检测、影像学和电生理学研究结果。我们还强调恶性肿瘤筛查的重要性，因为传统胸部CT对肺癌呈阴性，但PET-CT对小细胞肺癌提出了高度怀疑。结论 LEMS 罕见，伴有早期呼吸衰竭和宽大、固定的瞳孔。关于重复性神经刺激，重要的是刺激足够长的时间以看到增量反应。此外，这项研究说明了当常规 CT 阴性高度怀疑小细胞肺癌时，使用 PET-CT 进行恶性肿瘤筛查的重要性。可根据合理要求提供数据。