Chorea

Chorea describes involuntary, irregular, purposeless on-rhythmic movements which are rapid and jerky and flow from one part of the body to another. The movements may be simple or elaborate. Choreiform movements often merge with more purposeful movements, which may then mask the chorea.

• Neonatal: cerebral palsy, anoxia, kernicterus
• Senile chorea
• Pregnancy: chorea gravidarum; often in women with history of rheumatic fever, begins in first trimester and resolves before or soon after delivery
• Hereditary: e.g. Huntington's disease, Friederich's ataxia, Wilson's disease
• Drug-induced: e.g. anticonvulsants, phenytoin, levodopa, dopamine agonists, tricyclics, benzodiazepines, oestrogens, amphetamines, cocaine
• Toxins: e.g. carbon monoxide, mercury
• Endocrine and metabolic: e.g. thyrotoxicosis, hypoparathyroidism, hyponatraemia, hypomagnesaemia, hypocalcaemia, hypoglycaemia
• Nutritional: e.g. pellagra, beriberi
• Infection: e.g. Sydenham's chorea (20% of cases of rheumatic fever), post-infective states, encephalitis lethargica, Creutzfeldt-Jakob disease.
• Vasculitis or connective tissue disease, e.g. systemic lupus erythematosus, Behcet's disease, polyarteritis
• Multiple sclerosis
• Polycythaemia or other hyperviscosity syndromes
• Subcortical infarction or haemorrhage
• Hemichorea is often due to a structural brain lesion, e.g. vascular or tumour

• Chorea is characterised by brief, irregular, jerky and purposeless involuntary movements of the distal extremities and face.
• Involvement of the face may lead to grimacing, tongue movements or grunting noises.
• Choreiform movements are aggravated by anxiety and stress and subsides during sleep¹.
• Movements are not repetitive or rhythmic, but appear to flit randomly from one part of the body to another.
• Chorea often occurs with athetosis, which adds twisting and writhing movements.
• When shaking hands there may be associated tremor, dystonia and variable force of the grip of the patient's hand.
• Holding out the hands often shows a typical dystonic posture with finger and thumb hyperextension and wrist flexion.
• Abdominal reflexes are usually brisk; tendon reflexes are reduced and may be pendular due to hypotonia.

Assessment for a possible cause includes:

• Mental state: Huntington's disease
• Face and eyes: exophthalmos (thyrotoxicosis), Kayser-Fleischer rings (Wilson's disease), conjunctival injection (polycythaemia)
• Skin: SLE
• Heart: rheumatic fever

Investigations will depend on the presentation of the individual patient but will include¹:

• Full blood count.
• Electrolytes: calcium, magnesium.
• Renal function tests.
• Liver function tests
• Thyroid function tests
• VDRL, HIV antibody.
• ESR and antinuclear antibody titre: for suspected autoimmune aetiology.
• Antistreptolysin O titre: suspected streptococcal infection.
• Lyme disease: in cases with recent travel history to endemic areas.
• Toxoplasmosis titres: in immunosuppressed patients.
• A copper study with serum ceruloplasmin and 24 hour urine copper: in cases with movement disorders under the age of 40, especially with a family history of neuropsychiatric symptoms or medical history of liver disease
• MRI: in rule to intracranial structural lesion
• EEG: to differentiate between paroxysmal movement disorders and seizures.

• When mild, chorea can be difficult to differentiate from restlessness¹.
• May need to be differentiated from seizures.
• Choreiform movements may be difficult to distinguish from slower, writing athetosis movements. Choreoathetosis describes both.
• Myoclonus is much more rapid and does not flow from one muscle to another.

• There is no standard course of treatment for chorea.
• Management depends on the associated disease.
• Adjusting medication dosages can treat drug-induced chorea.
• There is currently no cure for Huntington's disease.
• Tetrabenazine has been shown to be safe and effective in treating chorea in Huntington's disease² but may not produce a sustained benefit.
• The chorea of Sydenham's chorea may be controlled with diazepam, haloperidol or tetrabenazine.

The prognosis for individuals with chorea depends on the underlying disease.