Chorea is repetitive, brief, jerky, rapid involuntary movements that start in one part of the body and move abruptly, unpredictably, and often continuously to another part. Athetosis is a continuous stream of slow, flowing, writhing involuntary movements. Hemiballismus is a type of chorea, usually involving violent, flinging involuntary movements of one arm.
Chorea and athetosis, which may occur together as choreoathetosis, are not disorders. Rather, they are symptoms that can result from several very different disorders. Chorea and athetosis result from overactivity in the basal ganglia, the part of the brain that helps smooth out and coordinate movements initiated by nerve impulses from the brain. In most forms of chorea, an excess of dopamine, the main neurotransmitter used in the basal ganglia, prevents the basal ganglia from functioning normally. Drugs and disorders that increase dopamine levels or increase the sensitivity of nerve cells to dopamine tend to worsen chorea and athetosis.
Chorea and athetosis occur in Huntington's disease, a hereditary degenerative disorder. Chorea may occur in Sydenham's chorea (also called St. Vitus' dance or Sydenham's disease), a complication of rheumatic fever (a childhood infection caused by certain streptococci). Sydenham's chorea is characterized by jerky, uncontrollable movements and can last for several months.
Chorea sometimes develops in older people for no apparent reason. This chorea, called senile chorea, tends to affect the muscles in and around the mouth. Chorea can also affect women during the first 3 months of pregnancy (a condition called chorea gravidarum), but it disappears without treatment shortly after they give birth. Rarely, a similar chorea develops in women taking oral contraceptives. Chorea can also result from lupus (systemic lupus erythematosus), overactivity of the thyroid gland (hyperthyroidism), a tumor or stroke affecting a part of the basal ganglia called the caudate nucleus, and certain drugs such as antipsychotic drugs.
Chorea typically involves the hands, feet, and face. The jerky movements seem to flow from one muscle to the next and may seem dancelike. The movements may merge imperceptibly into purposeful or semipurposeful acts, sometimes making the chorea hard to identify.
Athetosis usually affects the hands and feet. The slow writhing movements often alternate with holding parts of the limbs in certain positions (postures) to produce a continuous, flowing stream of movement.
Hemiballismus affects one side of the body. The arm is affected more often than the leg. It is usually caused by a stroke affecting a small area just below the basal ganglia called the subthalamic nucleus. Hemiballismus may be temporarily disabling because when a person tries to move the limb, it may fling out uncontrollably.
Chorea due to hyperthyroidism usually lessens when that disorder is treated. Sydenham's chorea and chorea caused by a stroke often gradually subside without treatment. If chorea is caused by a drug, stopping the drug may help, but the chorea does not always disappear. Pregnant women with chorea may be treated with barbiturates during the pregnancy.
Drugs that block dopamine's action may help control the abnormal movements. These drugs include antipsychotic drugs (see see Table: Antipsychotic Drugs), such as fluphenazine, haloperidol, and risperidone. Drugs that reduce the amount of dopamine released, such as reserpine and tetrabenazine, may also help. However, improvement may be limited.
Hemiballismus usually goes away on its own after several days, but it sometimes lasts for 6 to 8 weeks. Antipsychotic drugs may help suppress hemiballismus.
Last full review/revision August 2007 by David Eidelberg, MD; Michael Pourfar, MD