[Lambert-Eaton myasthenic syndrome with acute respiratory failure associated with small cell lung cancer].

HISTORY AND ADMISSION FINDINGS: A 53-year-old woman had suffered from progressive lower limb weakness for 8 weeks. She was not able to walk on her own. Two hours after admission endotracheal intubation and mechanical ventilation became necessary because of acute respiratory failure.

INVESTIGATIONS: Chest radiograph and computerized tomography showed a huge lesion originating from the lower lobe of the left lung with mediastinal infiltration. Histological examination of bronchoscopical-guided biopsy disclosed small cell lung cancer. Electrophysiological studies revealed an incremental response on high-rate stimulation in the repetitive nerve stimulation test. Autoantibodies to P/C-type voltage-gated calcium channels were detected. Further, laboratory test results revealed hyponatremia (100 mmol/l) and elevated ADH (11 pg/ml).

DIAGNOSIS, TREATMENT AND CLINICAL COURSE: These results led to the diagnosis of paraneoplastic Lambert-Eaton myasthenic syndrome (LEMS) with acute respiratory failure caused by small cell lung cancer. Additionally, SIADH (syndrome of inappropriate antidiuretic hormone secretion) was diagnosed as another paraneoplastic disease. Because of a prolonged weaning process resulting from inadequacy of mechanical ventilation, administration of intravenous immunoglobulins and chemotherapy with cisplatin and etoposide were undertaken. This made successful extubation possible after 7 days. In spite of all supportive treatment, clinical deterioration occurred. The patient died 27 days after the small cell lung cancer had been diagnosed.

CONCLUSION

The Lambert-Eaton myasthenic syndrome should be considered in cases of unexplained acute respiratory failure and clinical evidence of neoplastic disease.