Paraneoplastic movement disorders.

Paraneoplastic movement disorders are rare autoimmune nonmetastatic complications of cancer. Common paraneoplastic movement disorders include cerebellar syndrome, opsoclonus myoclonus, basal ganglia disorders, stiff person syndrome, and neuromyotonia. Syndromes usually present before cancer diagnosis and are commonly associated with one or more serum antibodies. Increasing numbers of antibodies have been identified (Hu, Yo, Ri, CV2, amphiphysin, Ma, Ta, Tr, NMDA, mGluR1, PCA2, ANNA-3, VGCCA). Antibodies are highly correlated with the likelihood of an underlying cancer and are closely associated with certain tumors. Clinical clues to paraneoplastic aetiology include speed of onset, severity, speed of progression, resistance to treatment, and more widespread neurological signs than one would expect from nonparaneoplastic aetiologies. Cancer should be sought in those with classical presentations and those with possible presentations who have paraneoplastic antibodies. If no tumor is found on initial investigation, interval screening is advisable. The most common associated cancers found are small cell lung cancer, breast, gynaecological, testicular, lymphoma, and thymoma. Early identification and treatment sometimes leads to neurological improvement and may improve cancer prognosis. Prognosis is dependent on the tumor type and its likely response to treatment.