Lambert-Eaton myasthenic syndrome: Report of a chinese patient

A 55-year-old man, with Lambert-Eaton myasthenic syndrome (LEMS) and small cell lung cancer, developed proximal weakness of limbs and autonomic dysfunction. Detailed electrophysiological studies revealed small compound muscle action potential amplitudes, decremental responses to 3Hz and incremental responses to maximal voluntary contractions. A 20Hz repetitive nerve stimulation (RNS) for 1 second revealed decremental responses. Results of this 20Hz high rate RNS were contradictory features seen in patients with LEMS. However, both prolonged 20Hz RNS for 5 seconds and 50Hz RNS for 1 second revealed incremental responses and confirmed the diagnosis. Thus, 50Hz RNS was more sensitive than 20Hz and sometimes prolonged 20Hz RNS is indicated, when documenting the disease.