Lambert–Eaton Myasthenic Syndrome

Lambert–Eaton myasthenic syndrome (LEMS) is an uncommon presynaptic disorder of the neuromuscular junction. It presents with progressive proximal weakness, depressed tendon reflexes, and autonomic dysfunction. The electrophysiological triad of low amplitude motor potentials, decremental response on low-rate repetitive nerve stimulation (RNS), and increment on high-rate RNS are characteristic. Often, antibodies against the voltage-gated calcium channels are detected and patients are known to have malignancies, mainly small cell carcinoma of the lung. The benefits of tumor therapy, immunotherapy, and 3–4 diaminopyridine are known.