A 62-year-old man who had suffered from instability of gait and
double vision for two months was admitted to our hospital because of weakness of the extremities and
ataxia of the extremities and trunk. Chest X-rays and CT scans showed enlargement of the left hilar lymph nodes and a nodular shadow in the left lung. Transbronchial biopsy revealed
small cell lung cancer. We diagnosed the patient with two conditions:
paraneoplastic cerebellar degeneration (PCD), based on
cerebellar ataxia, the presence of Hu antineuronal
antibodies, and the absence of cerebellar
atrophy and
malignancy; and
Lambert-Eaton myasthenic syndrome (LEMS), based on weakness of the extremities, the presence of P/Q-type voltage-gated
calcium channel antibodies, and waxing in the evoked electromyogram. Anticancer chemoradiation
therapy that was started within three months of symptom onset resulted in reductions in size of the hilar lymph nodes and the nodule. Concurrently,
cerebellar ataxia, weakness of the extremities, and
double vision all disappeared. Anticancer
chemotherapy is effective against LEMS while usually less effective against PCD. Early commencement of anticancer
chemotherapy is recommended for the treatment of PCD with LEMS.