Hyperkinetic movement disorders associated with HIV and other viral infections.

Viral infections of the central nervous system often result in a spectrum of movement disorders, ranging from slowness and rigidity to hyperkinetic movements such as chorea, ballism, dystonia, and myoclonus. The basal ganglia are especially susceptible to some viruses, because of their intrinsic neurotropism, a predilection of opportunistic infections for the deep gray matter of the brain, and possibly the mounting of an autoimmune response against basal ganglia antigens. Viral encephalitides reviewed here include those caused by the human immunodeficiency virus, influenza A virus, the Flavivirus family (such as West Nile virus, Japanese encephalitis virus), and herpes simplex. Hyperkinetic movement disorders associated with prion diseases will also be discussed. The clinical features, etiology, pathogenesis, diagnosis, and treatment of the underlying infections and ensuing movement disorders will be reviewed.