Lambert –Eaton myasthenic syndrome (LEMS): a rare autoimmune presynaptic disorder often associated with cancer

AbstractLambert –Eaton myasthenic syndrome (LEMS) is a rare autoimmune neuromuscular junction disorder that is related to the loss of functional P/Q-type voltage-gated calcium channels (VGCCs) on presynaptic nerve terminals. Up to 60% of cases occur as a paraneoplastic disorder (SCLC-LEMS), most commonly in assoc iation with small cell lung cancer. The remaining cases have an idiopathic non-tumor etiology but are associated with underlying autoimmune disease (NT-LEMS). Patients with LEMS invariably experience progressive proximal muscle weakness, often accompanied by general fatigue and autonomic symptoms. S ome LEMS clinical symptoms overlap with those of other myasthenic syndromes, most commonly myasthenia gravis, which can contribute to misdiagnosis or delayed diagnosis. Prognosis is related to the presence of cancer or autoimmune disease and the severity/distribution of muscle weakness. Cause of dea th in patients with SCLC-LEMS is typically tumor progression, whereas NT-LEMS does not reduce life expectancy. LEMS diagnosis is supported by a threefold approach: clinical features, electromyography, and anti-VGCC antibody serology. LEMS is a clinically important early indicator of possible cancer; therefore, a LEMS diagnosis should immediately prompt rigorous oncological screening and surveillance. Symptomatic treatment of LEMS typically involves medications that improve neurotransmission (e.g., the potassium channel blocker amifampridine [3,4-diaminopyridine]), with addit...
Source: Journal of Neurology - Category: Neurology Source Type: research