Hyperglycemic nonketotic states and other metabolic imbalances.

Hemichorea and generalized chorea are well-recognized syndromes associated with nonketotic hyperglycemia. This condition usually occurs in older age, affects females more than men, and often heralds a new diagnosis of diabetes, usually type 2. It may resolve over days with treatment of the underlying hyperglycemia or persist for years. Magnetic resonance imaging is very characteristic, and shows T1 hyperdensity in the striatum. The underlying pathophysiology is not clear, but recent evidence suggests that the imaging may represent zinc, as opposed to calcium. Tetrabenazine has worked well when symptomatic treatment is required. Other rare causes of metabolic choreas include hypoparathyroid abnormalities, hypoglycemia, and hypernatremia.