Chorea is characterized by involuntary, rapid, brief, irregular movements that seemingly flow from one body part to another, thus giving the appearance of dancing. Chorea may be a manifestation of a neurodegenerative disease or a complication of systemic, toxic or metabolic diseases.
Incidence and prevalence is variable, depending on etiology.
- Family history of chorea
- Exposure to certain medications
- Immunological factors
Chorea can be seen with a number of hereditary conditions. Classic examples are Huntington's disease (HD) chorea, neuroacanthocytosis, and benign hereditary chorea.
Drug-induced chorea can be prevented by avoiding dopamine blocking drugs.
Chorea is a hyperkinetic movement disorder caused by excessive dopaminergic activity may be associated with dopamine receptors super sensitivity.
- Multiple etiologies of chorea:
- Genetic: HD, HD-like illnesses, neuroacanthocytosis, McLeod's syndrome, Wilson's disease (WD), benign hereditary chorea (BHC), spinocerebellar atrophy type 2, 3, and 17), Dentatorubropallidoluysian degeneration (DRPLA), ataxia-telangiectasia, ataxia associated with oculomotor apraxia, neuroferritinopathy, pantothenate kinase-associated degeneration, Leigh's disease and other mitochondriopathies and Lesch–Nyhan disease
- Immunologic: Sydenham's chorea (SC), systemic lupus erythematosus, antiphospholipid antibody syndrome and paraneoplastic syndromes
- Drug/toxins: Amphetamine, anticonvulsants (Phenytoin), carbon monoxide, CNS stimulants (methylphenidate, pemoline, cyproheptadine), cocaine, dopamine agonists, dopamine-receptor blockers (Metoclopramide), ethanol, levodopa, levofloxacin, lithium, manganese, and mercury toxicity, sympathomimetics, theophylline, tricyclic antidepressants
- Infectious: HIV encephalitis, diphtheria, Scarlet fever, measles, mumps, West Nile encephalitis, neurocysticercosis, neurosyphilis, Lyme's disease, and toxoplasmosis
- Endocrine/metabolic dysfunction: Hyperthyroidism, chorea gravidarum, hypo- and hyperparathyroidism and Addison's disease. Renal or hepatic encephalopathy and other electrolyte abnormalities
- Vascular: Post-pump chorea (cardiac surgery), basal ganglia infarctions/hemorrhage, subdural hematoma
- Miscellaneous: Anoxic encephalopathy, cerebral palsy, Kernicterus, multiple sclerosis, nutritional (e.g., B12 deficiency), posttraumatic (brain injury)
COMMONLY ASSOCIATED CONDITIONS 
- Benign hereditary chorea: Characterized by the onset of chorea in childhood, which is nonprogressive and self-limiting in most cases. Patient may have slight motor delay, ataxia and handwriting changes. Autosomal dominant illness, with a mutation in the TITF-1 gene.
- Essential/senile chorea: Adult onset chorea presents after age 60 nonprogressive and without dementia, psychiatric disturbance, or a family history of chorea and no other identifiable cause.
- HD: Autosomal dominant disease related to expansion of unstable stretch of CAG trinucleotide repeats in the huntington gene on chromosome 4p. It is characterized by chorea, ataxia, cognitive changes and psychiatric disturbances.
- Dentatorubropallidoluysian atrophy: Autosomal dominant trinucleotide (CAG) repeat disorder most prevalent in Japan. Manifested by variable combination of myoclonus, epilepsy, mental retardation in early onset before age 20 and in late onset manifested by ataxia, choreoathetosis, dystonia, and tremor
- WD: Autosomal recessive disease. The underlying defect is impaired biliary excretion of copper due to a defect in the WD gene, Wc1, on chromosome 13q, which encodes for a copper transporting adenosine triphosphatase (ATPase). Copper toxicity results in the deposition of copper initially in the liver and then the brain. Neurologic manifestations include tremor, chorea, dystonia, tics, myoclonus, ataxia, and Parkinsonism.
- Neuroacanthocytosis: It refers to a group of neurological disorders in which acanthocytes are seen on peripheral blood films: Several conditions can cause the combination of chorea and acanthocytosis.
- Choreoacanthocytosis: Patients have autosomal recessive inheritance showing linkage to chromosome 9q21. Symptoms first begin in 3rd–4th decade of life with lip and tongue biting followed by orolingual dystonia, generalized chorea, and motor tics. Other features include cognitive and personality changes, seizures, dysphagia, dysarthria, parkinsonism, areflexia with evidence of axonal neuropathy.
- McLeod phenotype is an X-linked recessive form of acanthocytosis associated with chorea, personality disorder, seizures, depression but do not exhibit lip biting or dysphagia.
- Sydenham chorea: Most common form of autoimmune chorea worldwide, is a major feature of acute rheumatic fever (ARF), a complication of group A β-hemolytic Streptococcus infection. Clinically, it is characterized by a combination of chorea, behavioral abnormalities, and cognitive changes. The usual age at onset of SC is 8–9 years. Typically, patients develop this disease 4–8 weeks after an episode of group A β-hemolytic streptococcal pharyngitis. It does not occur after streptococcal infection of the skin. Pathogenesis of SC is related to circulating cross-reactive antibodies.
- Other autoimmune choreas: Other immunologic causes of chorea are systemic lupus erythematosus (SLE), primary antiphospholipid antibody syndrome (PAPS), and vasculitis. Autoimmune chorea has rarely been reported in the context of paraneoplastic syndromes associated with CV2/CRMP5 antibodies in patients with small-cell lung carcinoma or malignant thymoma.
- Vascular choreas: Chorea is an unusual complication of acute vascular lesions, seen in less than 1% of patients with acute stroke. Vascular hemichorea, or hemiballism, is usually related to ischemic or hemorrhagic lesions of the basal ganglia and adjacent white matter in the territory of the middle or the posterior cerebral artery. Another rare form of vascular chorea is “postpump chorea,” a complication of extracorporeal circulation.
Chorea can occur during pregnancy, i.e., chorea gravidarum (CG), and typically resolves following delivery. However, the occurrence of CG may be the initial manifestation of systemic lupus erythematosus, HD, and the antiphospholipid antibody syndrome.
