Paroxysmal kinesigenic choreoathetosis in hyperthyroidism.

Paroxysmal kinesigenic choreoathetosis is an unusual movement disorder often triggered by attempts to use the limbs, and has sometimes been associated with diffuse or focal brain injury. We report its occurrence in hyperthyroidism, with which choreoathetosis has rarely been described in the past without known cause. Choreoathetosis has also occurred with other metabolic and toxic disorders, and the mechanism is uncertain. The development of involuntary movements activated by limb motion during hyperthyroidism suggests an influence by thyroid hormone or metabolic state on motor neurone excitability or motor system organization.