Chorea

Chorea is a movement disorder (dystonia). It comes from the Greek word "choreia" - dancing. It describes involuntary, irregular, random and flowing movements which flit 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.

Other terms which may be classified under 'chorea' (or as separate dystonias) are:

• Athetosis: sinuous writhing movements, often of the hands. If this occurs with chorea, it is called choreoathetosis.
• Ballism and hemiballismus: Large-amplitude, proximal, flinging movements (hemiballismus if unilateral).

• Inherited:
  • Huntington's disease
  • Benign hereditary chorea
  • Wilson's disease
  • Neuroacanthocytosis
  • Dentatorubralpallidoluysian atrophy
  • Other rare, inherited neurological conditions which include chorea
• Acquired:
  • Drug-induced: antipsychotics (tardive dyskinesia), dopamine agonists, levodopa, anticonvulsants; more rarely, CNS stimulants, lithium, antihistamines, oestrogens.
  • Immune mediated:
    • Sydenham's chorea (St Vitus' Dance - the commonest, may be post-streptococcal infection)
    • Other immune-mediated choreas: can occur in: systemic lupus erythematosus (SLE), polyarteritis nodosa, Behcet's disease and CNS angiitis
  • Infectious chorea:
    • Can occur with meningitis, encephalitis, Lyme disease and HIV (e.g. in acquired immune deficiency syndrome with toxoplasmosis abscess)
  • Vascular chorea:
    • Stroke
    • Polycythaemia (unknown mechanism)
  • Hormonal disorders:
    • Hyperthyroidism
    • Hypoparathyroidism with hypocalcaemia
    • Pregnancy and oral contraceptives (rare; may have a history of Sydenham's chorea)
  • Metabolic and toxic:
    • Electrolyte and biochemical disturbance, e.g. hyper- and hyponatraemia, hyper- and hypoglycaemia, hypomagnesemia, hypocalcaemia, hepatic and renal failure, abetalipoproteinaemia.
    • Vitamin deficiency: B1 and B12
    • Toxins, e.g. carbon monoxide, alcohol, methanol, amphetamines, solvents, heroin, thallium, mercury, cyanide and manganese
  • Paraneoplastic syndromes, e.g. small cell carcinoma of lung, renal cell carcinoma, ovarian cancer and lymphoma
  • Postoperative - following childhood cardiac surgery
  • Trauma, including cerebral palsy
  • Intracranial tumours
  • Senile chorea

• 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 sleep.¹
• 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 or with the patient gripping the examiner's finger, there may be variable force of grip. This can be an early sign.

Assessment for a possible cause includes:

• Time course of symptoms (acute/gradual onset), progression, medical history and medication
• Systems and neurological examination, including:
  • Signs of infectious disease
  • Focal neurological signs
  • 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 depend on the presentation of the individual patient, and include:

• Full blood count
• Electrolytes, including calcium and magnesium
• Renal function tests
• Liver function tests
• Thyroid function tests
• Consider also:
  • Tests for syphilis, HIV, toxoplasmosis, Lyme disease
  • Antistreptolysin O titre: for suspected streptococcal infection
  • ESR and autoimmune serology: for suspected autoimmune aetiology
  • Copper studies (for Wilson's disease, if under age 40 or family history of liver disease or neuropsychiatric disease)
  • MRI: for intracranial structural lesion
  • EEG: if seizures rather than movement disorder are considered

• When mild, chorea can be difficult to differentiate from restlessness.¹
• May need to be differentiated from seizures.
• Choreiform movements may be difficult to distinguish from slower, writhing 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, e.g:

• Adjusting medication dosages can treat drug-induced chorea.
• Vitamin E may hasten resolution of tardive dyskinesia.¹
• Tetrabenazine has been shown to be safe and effective in treating chorea in Huntington's disease³ 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.