Paraneoplastic cerebellar degeneration may occur in association with 
Lambert-Eaton myasthenic syndrome (LEMS), but to our knowledge, the 
co-occurrence of paraneoplastic opsoclonus-myoclonus syndrome and LEMS has not 
been previously reported. A 67-year-old woman presented with a complex partial 
seizure and evolving ocular flutter, opsoclonus, myoclonus and 'cerebellar' 
signs, all of which improved spontaneously within 6 weeks. Approximately 8 weeks 
after symptom onset, the patient became encephalopathic, she had a further 
complex partial seizure, and she became areflexic with potentiation of deep 
tendon reflexes. Radiological, bronchoscopic and histological investigations 
revealed small-cell lung cancer, and neurophysiological investigations confirmed 
a diagnosis of LEMS. High-titre anti-P/Q-type voltage-gated calcium-channel 
antibodies were identified in the serum, which increased as the signs of 
opsoclonus and myoclonus resolved. The encephalopathy and clinical features of 
LEMS responded dramatically to chemotherapy and radiotherapy. Spontaneous 
improvement of paraneoplastic opsoclonus-myoclonus syndrome may occur, and this 
syndrome may occur in association with LEMS. Antivoltage-gated calcium-channel 
antibodies are not implicated in the pathogenesis of paraneoplastic 
opsoclonus-myoclonus syndrome.