Lambert-Eaton Myasthenic Syndrome: A Very Rare and Tortuously Exasperating Facet of Pre-Synaptic Disorder of Neuromuscular Junction

Lambert-Eaton Myasthenic Syndrome (LEMS) is a very rare and unusual autoimmune disorder of Neuromuscular Junction (NMJ) that is associated with impaired neuromuscular transmission due to loss of voltage-gated calcium channel (VGCC) present on the pre-synaptic nerve terminal. Of all the different proteins like synaptotagmin that are attacked by auto-antibodies, P/Q-type of VGCC is found to be targeted in 90 % of patients. The influx of calcium through VGCC is important for exocytosis of synaptic vesicles. LEMS is a clinical “triad” of proximal muscle weakness, areflexia, and autonomic dysfunctions. Half of the LEMS patients are almost always associated with the small-cell lung carcinoma (SCLC), the knowledge of which has led to the finding of different paraneoplastic, and non-tumor related neurological disorders of the central nervous system. The rest of the people present idiopathic LEMS. The repetitive nerve stimulation is the electrophysiological study that is the diagnostic test of choice. The diagnostic confirmation of LEMS is always followed by prompt screening of SCLC majorly by radiological screenings. Prognosis depends on the presence of SCLC and severity of weakness. If carcinoma is not found, symptomatic therapy is done but none of the drugs confer complete normalcy in symptoms. The supra-additive effect of amifampridine and GV-58 shown in pre-clinical trials is the anticipated long-run prospect in the LEMS treatment. A PubMed literature search was conducted by using keywords: “Lambert-Eaton”, “Myasthenic”, and “Syndrome”. A total of 1067 articles were found. A further selection of articles was made by excluding the non-relevant articles.