[Improvement of neurologic symptoms after chemoradiotherapy in a patient with small cell lung cancer associated with paraneoplastic neurologic syndrome].

A 53-year-old man was referred to our hospital for dry cough and a mass in the hilum of the right lung on chest CT which was diagnosed as small cell lung cancer by bronchofiberscopy (T3N2M0, stage IIIB). Also, he was aware of progressive muscle weakness in the lower extremities on the first consultation. An electromyogram showed neuropathic changes and did not show waxing phenomenon in response to high frequency repetitive stimulation. Sensory nerve conduction velocity was low, so we diagnosed small cell cancer associated with paraneoplastic sensory neuropathy. Serum antineuronal antibodies were negative. His neurological symptoms improved dramatically after chemoradiotherapy for small cell lung cancer. A complete response was obtained by concurrent chemoradiotherapy and prophylactic cranial irradiation was administrated. He is alive without recurrence at 11 months after the treatment.