Chorea and Athetosis
Chorea consists of repetitive, brief, jerky, large-scale, dancelike, uncontrolled movements that start in one part of the body and move abruptly, unpredictably, and often continuously to another; athetosis is a continuous stream of slow, sinuous, writhing movements, generally of the hands and feet.
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 abnormalities 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 disease. Chorea may also be caused by Sydenham's disease (also called St. Vitus' dance or Sydenham's chorea), a complication of rheumatic fever (a childhood infection caused by certain streptococci). Sydenham's disease is characterized by jerky, uncontrollable movements and can last for several months.
Chorea sometimes develops in older people for no apparent reason, affecting particularly the muscles in and around the mouth. This disorder is called senile chorea. Chorea also can affect women in 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.
Hemiballismus, a type of chorea, consists of continuous violent flinging movements on one side of the body. It affects the arm more than the leg. It is usually caused by a stroke affecting a very small area just below the basal ganglia.
If chorea is being caused by a drug, stopping the drug may help, but the chorea does not always disappear. Drugs that block dopamine's action may help control the abnormal movements. These drugs include antipsychotic drugs (see Section 7, Chapter 107), such as haloperidol and fluphenazine.
Antipsychotic drugs may also help people with hemiballismus. However, hemiballismus usually goes away on its own after several days, although it sometimes lasts for 6 to 8 weeks.