Chorea
What is Chorea?
Chorea was derived from the Greek word “khoreia”, literally meaning coral dance. Patients with chorea have jerky involuntary movement of the muscles. This usually involves the limbs, upper part of the body and the face. The severity of chorea can range from mere twitching and fidgeting to persistent, violent movements of the limbs.
Patients with chorea are unable to maintain a sustained posture. The body movements are continually changing and move from one side of the body to another. They also tend to have an awkward gait when they walk. It has been described as being dance–like by some people. In certain cases, patients will have impaired speech because the chest muscles have been affected.
Patients who are strongly affected by chorea also alternately squeeze and release the object they are holding. When they attempt to stick their tongue out, the tongue often pops in and out.
What are the causes of chorea?
Chorea is caused by excessive dopaminergic activity in the part of the brain in charge of controlling the normal movements of the muscles known as the basal ganglia. The excessive dopamine results in spontaneous uncontrollable muscle movements.
Many diseases have been identified as contributors of the excessive dopaminergic activity. These include:
- Huntington’s disease, a hereditary disease
- Sydenham chorea, which occurs in rheumatic fever
- Chorea gravidarum during in the first trimester of pregnancy
- Hyperthyroidism
- Senile chorea
- Hypocalcemia
- Diseases affecting the brain and spinal cord such as systemic lupus erythematosus (SLE) and encephalitis
- Lesions in the basal ganglia
- Usage of antiepileptic drugs such as those in Parkinson’s disease
- Usage of lithium, amphetamines and antinausea medications
How is chorea diagnosed?
Chorea diagnosis usually involves medical history and conducting a thorough clinical exam. The doctor looks into the symptoms, family history, and medication history.
Syndeham’s chorea most often occurs in children aged between 6 and 14. Huntington’s disease typically affects people aged 35 and above. Chorea can only be observed after that. Huntington’s chorea affects both boys and girls equally whereas girls are twice more likely to get Syndenham chorea compared to boys.
For patients suffering from both ballismus and chorea, the doctor may arrange a computed tomography (CT) scan or magnetic resonance imaging (MRI) to investigate if any of the blood vessels in the basal ganglia are blocked or ruptured.
Sometimes doctors need to test a sample of the patient’s cerebrospinal fluid to investigate if they have encephalitis or neurosyphilis.
How is chorea treated?
The treatments available can only treat the symptoms of chorea. Normally, doctors do not treat chorea on its own unless it poses harm to the patient’s own body or causes embarrassment due to the involuntary movements.
Most of the drugs given suppress the activity of dopamine in the basal ganglia. Some examples of these drugs are neuroleptics, dopamine-depleting agents and GABAergic drugs. However, they carry serious side effects such as muscle stiffness. These drugs are not given to pregnant women because they may harm the fetus. Instead, they are given a mild tranquilizer instead.
Deep brain simulation is a possible surgical option for patients who do not respond to medication. It can only reduce symptoms but will not cure chorea.
What is the prognosis of chorea?
The outlook of chorea depends on its cause. Syndenham chorea can be resolved using antibiotics. On average, patients will recover within 1 to 6 months. On the other hand, Huntington’s chorea cannot be cured and many patients are only able to live up to 25 years after the first symptoms have surfaced. Chorea caused by metabolic disorders usually stop once the hormonal balances have been corrected appropriately.