A recently diagnosed case of small cell carcinoma of lung presented with slowly progressive proximal muscle weakness along with ptosis of eyelids and diplopia. O/E: - DTRs-absent Autonomic dysfunctions like frequent dryness of mouth were present. The doctor advised repetitive nerve stimulation test. There was increase in compound muscle action potential amplitude and this increase was >100% following exercise or with high frequency repetitive nerve stimulation. On serological testing, antibodies will be found against which channels: -

This is a case of Lambe Eaton syndrome occurring in the setting of small cell carcinoma of lung. RNS study shows incremental response which goes in or of Lambe Eaton syndrome (LEMS). Lambe-Eaton syndrome Presents with proximal muscle weakness Ptosis and diplopia Absent DTRs. Autonomic dysfunction Autoantibodies directed against P/Q-type calcium channels at the motor nerve terminals Found in 85% of LEMS patients. These impair the release of ACh from nerve terminals. In older adults, most LEMS is associated with malignancy. Most common malignancy associated is commonly small-cell lung cancer (SCLC)