- 期刊
Lambert-Eaton Myasthenic Syndrome Before Diagnosis of Poorly-Differentiated Neuroendocrine Carcinoma in the Subcarinal Region-A Case Report
摘要
Lambert-Eaton myasthenic syndrome (LEMS) is a rare immune-mediated disorder of the neuromuscular junction (NMJ) that is accompanied by or preceded by malignancy. The diagnosis of LEMS relies on the results of repetitive nerve stimulation (RNS) testing or detection of auto-antibodies against the voltage-gated calcium channel (VGCC). The RNS test is inexpensive; however, anti-VGCC antibody testing is expensive and is available in few research institutions. The characteristic findings of LEMS upon RNS include a low amplitude of the compound muscle action potential (CMAP) during rest and a significantly increased CMAP amplitude, usually by more than 100%, after exertion or high-frequency (30-50 Hz) repetitive stimulation. Here, we report the case of a middle-aged man who presented with progressive predominantly-proximal muscle weakness, bilateral ptosis, dysarthria, and dysphagia with diurnal variation, which worsened in the evening. He had visited many hospitals and underwent various examinations, including magnetic resonance imaging (MRI) of the brain and cervical spine, but the results were inconclusive. At our hospital, RNS testing showed a significant incremental response, and the patient was diagnosed with LEMS after being screened for occult malignancy. A neuroendocrine carcinoma was discovered in the subcarinal region and was surgically removed. No tumor recurrence ensued in the subsequent 2 years. This was the first reported case of neuroendocrine carcinoma associated with LEMS in Taiwan. Our findings highlight the importance of careful clinical observation and the use of inexpensive electrophysiological testing to diagnose LEMS. Early detection and treatment of the underlying malignancy can improve the prognosis.
延伸閱讀
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