What are the paraneoplastic movement disorders?
Opsoclonus myoclonus designates a combination of rapid, erratic, involuntary movements of the eyes, with multifocal myoclonus (dancing eyes–dancing feet syndrome). Most cases occur between ages 6 and 18 months.
Fifty percent of cases are related to an underlying neoplasm, especially neuroblastoma.
This syndrome also occurs in adults with brain stem encephalitis, either paraneoplastic or infectious (Whipple’s disease). Steroids dramatically improve this form of myoclonus.
A few cases have been reported in patients with SPS, breast cancer, and autoantibodies against amphiphysin.
Ataxia is another well-established paraneoplastic movement disorder.
The mechanism is cerebellar degeneration related to anti-Purkinje cell antibodies.
There are also reports of parkinsonism, chorea, dystonia, segmental rigidity, and action and segmental myoclonus as remote effects of neoplasm.