neurologic disorders
Chorea, Athetosis, and Hemiballismus
Introduction
Choreais 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.Hemiballismusis 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 athetosisare 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 None Other causesof chorea include Hyperthyroidism None Hypoparathyroidism None Diabetes Mellitus (DM) None Systemic Lupus Erythematosus (SLE) that affects the central nervous system (CNS) Drugs (eg, Levodopa in patients with Parkinson disease, Adverse effects of antipsychotic drugs (due to use of typical and atypical antipsychotics or other drugs that block Autoimmune Disorders None Paraneoplastic Syndromes None Overview of Stroke None Pregnancy CNS 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 gravidarumoccurs 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. Hemiballismusis 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. 