Chorea

Overview
Chorea sancti viti (Latin for "St. Vitus' dance") is an abnormal involuntary movement disorder, one of a group of neurological disorders called dyskinesias. The term chorea is derived from a Greek word χορεία (a kind of dance), as the quick movements of the feet or hands are vaguely comparable to dancing or piano playing.

Presentation
Chorea is characterized by brief, irregular contractions that are not repetitive or rhythmic, but appear to flow from one muscle to the next.

These 'dance-like' movements of chorea (from the same root word as "choreography") often occur with athetosis, which adds twisting and writhing movements.

Causes
Chorea can occur in a variety of conditions and disorders.
 * Chorea is a primary feature of Huntington's disease, a progressive, hereditary movement disorder.
 * Twenty percent of children and adolescents with rheumatic fever develop Sydenham's chorea as a complication.
 * Chorea may also be caused by drugs (levodopa, anti-convulsants, anti-psychotics), metabolic disorders, endocrine disorders, and vascular incidents.

Ballism
When chorea is serious, slight movements will become thrashing motions; this form of severe chorea is referred to as ballism. Walking may become peculiar, and include odd postures and leg movements. Unlike ataxia and dystonia, which affect the quality of voluntary movements or parkinsonism, which is a hindrance of voluntary movements, the movements of chorea and ballism occur on their own, without conscious effort.

Complete List of Differential Diagnoses
In alphabetical order.


 * AIDS
 * Benign hereditary chorea
 * Chorea gravidarum
 * Dentatorubropallidoluysian atrophy (DRPLA)
 * Drug-induced
 * Huntington's Disease
 * Hyperthyroidism
 * Neoplasm
 * Neuroacanthocytosis
 * Stroke
 * Sydenham's chorea
 * Systemic Lupus Erythematosus
 * Wilson's Disease

History and Symptoms

 * Complete history required
 * Psychiatric symptoms (Huntington's)

Eyes

 * Appearance of Kayser-Fleischer rings in cornea is diagnostic for Wilson's disease (slit-lamp examination)

Laboratory Findings

 * Antinuclear antibody (ANA) to diagnose lupus
 * Serology (ASO) or throat cultures required to rule out streptococcal infection
 * Urinalysis (Wilson's)
 * Serum ceruloplasmin (Wilson's)
 * Thyroid function tests to diagnose hyperthyroidism

MRI and CT

 * CT scans and/or MRIs are required to rule out Huntington's disease and mass lesions

Echocardiography or Ultrasound

 * In order to diagnose carditis, an ECG may be indicated

Other Imaging Findings

 * In order to reveal cerebral and cerebellar atrophies in patients with DRPLA, various imaging studies are indicated

Other Diagnostic Studies

 * Genetic testing may be required for those patients suspected of having Huntington's disease
 * Peripheral smear for diagnostic neuroacanthocytosis

Treatment

 * Disease-specific treatment for AIDS, hyperthyroidism, lupus
 * Symptom resolution occurs within 15 weeks for those patients with Sydenham's chorea
 * Within nine years of onset of symptoms, neuroacanthocytosis is usually fatal
 * Discontinue use of drugs that may have caused drug-induced chorea
 * Genetic counseling is usually recommended for those patients with Huntington's disease

Acute Pharmacotherapies

 * For patients with Wilson's disease, copper-chelating agents are recommended
 * For patients with acute rheumatic fever, antibiotic therapy and possibly corticosteroids
 * For patients with Huntington's disease, antidepressants, neuroleptics