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Chorea, Athetosis, and Hemiballismus

By Hector A. Gonzalez-Usigli, MD, Professor of Neurology;Movement Disorders Clinic, HE UMAE Centro Médico Nacional de Occidente;Neurology at IMSS

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Chorea is a nonrhythmic, jerky, rapid, nonsuppressible involuntary movement, 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.

Chorea and athetosis are defined by clinical manifestations; many experts believe that when they occur together (as choreoathetosis), athetosis is a dystonia superimposed on chorea. 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, drugs that suppress dopaminergic activity, such as antipsychotics (eg, risperidone, olanzapine), and dopamine-depleting drugs (eg, reserpine, tetrabenazine) can be used to treat chorea. Antipsychotics may also help by lessening the neuropsychiatric symptoms commonly associated with Huntington disease (eg, impulsivity, anxiety, psychotic behavior). However, improvement may be limited and transient. These drugs may be judiciously used to treat choreas without a definable cause.

Other causes of chorea include

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). 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 when thyroid function or blood glucose level is normalized.

Chorea in patients > 60 should be thoroughly evaluated to identify the cause (eg, toxic, metabolic, autoimmune, paraneoplastic).

Chorea gravidarum occurs during pregnancy, often in patients who have had rheumatic fever. Chorea usually begins during the 1st trimester and resolves spontaneously at or after delivery. If treatment before delivery is necessary because chorea is severe, barbiturates are indicated because they have fewer fetal risks than other drugs used to manage chorea. Rarely, a similar disorder occurs 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 wk. If severe, it can be treated with an antipsychotic for 1 to 2 mo.