Chorea is random, flowing, nonsuppressible involuntary movements, mostly of the distal muscles and face; movements may be incorporated into semipurposeful acts that mask the involuntary movements. Athetosis (slow chorea) is nonrhythmic, slow, writhing, sinuous movements predominantly in distal muscles, often alternating with postures of the proximal limbs. Hemiballismus is unilateral rapid, nonrhythmic, nonsuppressible, wildly flinging movement of the proximal arm and/or leg; rarely, such movement occurs bilaterally (ballismus). Hemiballismus may be considered a severe form of chorea.
(See also Overview of Movement and Cerebellar Disorders.)
Chorea and athetosis result from impaired inhibition of thalamocortical neurons by the basal ganglia. Excess dopaminergic activity may be the mechanism.
Clinicians should seek and treat the cause of chorea whenever possible.
Huntington disease is the most common degenerative disorder causing chorea. In Huntington disease, medications that suppress dopaminergic activity, such as antipsychoticsdopamine
Other causes of chorea include
Systemic lupus erythematosus (SLE) that affects the central nervous system (CNS)
Pregnancy
Sydenham chorea can occur in rheumatic fever and may be the first symptom of it. A tumor or an infarct in the striatum (caudate or putamen) can cause acute unilateral chorea (hemichorea) on the opposite side of the body. Sydenham chorea and chorea due to infarcts of the caudate nucleus often lessen over time without treatment.
Chorea due to hyperthyroidism or another metabolic cause (eg, hyperglycemia) usually lessens over time when thyroid function or blood glucose returns to normal. If chorea does not subside after several weeks of metabolic control, clinicians should check for another cause such as stroke.
Chorea in patients > 60 should not be assumed to be senile chorea but should be thoroughly evaluated to identify the cause (eg, toxic, metabolic, autoimmune, paraneoplastic, drug-induced).
Chorea gravidarum is chorea that occurs during pregnancy. Although chorea gravidarum has various causes, it often occurs in pregnant patients who have had rheumatic fever. Chorea usually begins during the first trimester and resolves spontaneously at or after delivery. Identification of chorea's cause should be pursued as clinically indicated. A similar disorder can occur in women taking oral contraceptives.
Hemiballismus is caused by a lesion, usually an infarct, in or around the contralateral subthalamic nucleus. Although disabling, hemiballismus is usually self-limited, lasting 6 to 8 weeks. If severe, it can be treated with an antipsychotic for 1 to 2 months or, if antipsychotics are ineffective, with deep brain stimulation.
