Chorea

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Chorea (or choreia, occasionally) is an abnormal involuntary movement disorder, one of a group of neurological disorders called dyskinesias. The term chorea is derived from the Greek word χορεία (=dance; see choreia), as the quick movements of the feet or hands are comparable to dancing.

The term hemichorea refers to chorea of one side of the body, such as chorea of one arm but not both (analogous to hemiballismus).

Presentation

Chorea is characterized by brief, semi-directed, irregular movements that are not repetitive or rhythmic, but appear to flow from one muscle to the next.

These 'dance-like' movements of chorea often occur with athetosis, which adds twisting and writhing movements. Walking may become difficult, and include 

odd postures and leg movements.

Unlike ataxia, which affects 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. Thus, chorea is said to be a hyperkinetic movement disorder.

When chorea is serious, slight movements will become thrashing motions; this form of severe chorea is referred to as ballism or ballismus.

Causes

Huntington’s disease

Huntington's disease is a neurodegenerative disease and the commonest inherited cause of chorea. The condition was formerly called Huntington's chorea but was renamed because of the important non-choreic features including cognitive decline and behavioural change.

Other genetic causes

Other genetic causes of chorea are rare. They include the classical Huntington's disease 'mimic' or phenocopy syndromes, called Huntington's disease-like syndrome types 1, 2 and 3; inherited prion disease, the spinocerebellar ataxias type 1, 3 and 17, neuroacanthocytosis, dentatorubral-pallidoluysian atrophy (DRPLA), brain iron accumulation disorders, Wilson's disease, benign hereditary chorea, Friedreich's ataxia, mitochondrial disease and Rett syndrome.

Acquired causes

The commonest acquired causes of chorea are cerebrovascular disease and, in the developing world, HIV infection - usually through its association with cryptococcal disease.

Sydenham's chorea occurs as a complication of streptococcal infection. Twenty percent (20%) of children and adolescents with rheumatic fever develop Sydenham's chorea as a complication. It is increasingly rare, which may be partially due to penicillin, improved social conditions, and/or a natural reduction in the bacteria ( Streptococcus ) it has stemmed from. Psychological symptoms may precede or accompany this acquired chorea and may be relapsing and remitting. The broader spectrum of paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection can cause chorea and are collectively referred to as PANDAS.

Chorea gravidarum refers to choreic symptoms that occur during a women’s pregnancy. If left untreated, the disease resolves in 30% of patients before delivery but, in the other 70%, it persists. The symptoms then progressively disappear in the next few days following the delivery.

Chorea may also be caused by drugs (commonly levodopa, anti-convulsants and anti-psychotics).

Other acquired causes include systemic lupus erythematosus, antiphospholipid syndrome, thyrotoxicosis, polycythaemia rubra vera, transmissible spongiform encephalopathies and coeliac disease.

Form	Treatment
Huntington's-related	A common treatment is dopaminergic antagonists, although treatment is largely supportive. Tetrabenazine is the only FDA approved drug for the treatment of Huntington's Disease related chorea.
Sydenham's chorea	Haloperidol, carbamazepine and valproic acid. Usually involves antibiotic drugs to treat the infection, followed by drug therapy to prevent recurrence.
Chorea gravidarum	haloperidol, chlorpromazine alone or in combination with diazepam, also pimozide can also be used.
Wilson's disease	Reducing levels of copper in the body using D-penicillinamine, trientine hydrochloride, tetrathiomolybdate, and other chelating agents
Drug-induced chorea	Adjusting medication dosages.
Metabolic and endocrine-related choreas	Treated according to their causes.

Source: https://en.wikipedia.org/wiki/Chorea