Movement disorders caused by medical disease.

Movement disorders often occur in the context of medical illness, whether as the presenting sign of the illness, as a related feature of the underlying disease process, or as a complication of treatment. Early recognition of an underlying medical cause for movement disorders is essential because the treatment and prognosis differ significantly depending on the underlying pathophysiology. Parkinsonism, nonparkinsonian tremor, dystonia, and chorea have a wide variety of etiologies, requiring a careful medical history in the evaluation of new-onset movement disorders. The spectrum of medical diseases associated with these four syndromes is reviewed in this article.