Chorea is a movement disorder that stems from something wrong with the basal ganglia nerve structure deep in your brain. It causes involuntary movements of the hands, feet, and face.
These movements may be small and fidgety or big and vigorous. The name chorea derives from the Greek word for dance.
Symptoms of Chorea
The uncontrolled movements in chorea can take many forms. Some people with mild chorea can mask the movements as restlessness. In its more severe forms, chorea can be a series of violent movements that flow from one part of the body to another.
Certain types of movements are typical of chorea. Doctors use them to diagnose the condition. These movements include:
- Milkmaid's grip. People with chorea have difficulty keeping their muscles contracted. They may not have a steady grip. Instead, they squeeze and release in a milking motion.
- Jack-in-the-box tongue. When someone with chorea tries to stick out their tongue, it pops in and out of the mouth. This symptom is also called harlequin's tongue.
- Distinctive gait. People with chorea have a distinct way of walking that can be recognized by neurologists.
Chorea has several other variants:
- Athetosis. This is a slow form of chorea, where the movements have a twisting, squirming quality.
- Choreoathetosis. Choreoathetosis is a mix of chorea and athetosis, with movements that have a medium speed and intensity.
- Ballism or ballismus. This fast form of chorea is violent, where the limbs are flung about.
Causes of Chorea
Chorea originates in the basal ganglia — an area of the brain that controls movement. Scientists believe that chorea is triggered when the basal ganglia receive too much dopamine — a chemical that helps nerves function. Too much of dopamine can cause problems.
The most widely recognized cause of chorea is Huntington's disease — a hereditary disorder. But, there can be many other causes, some of which are very rare.
A child who got rheumatic fever after a strep throat or scarlet fever infection may show a temporary form of chorea.
People with autoimmune diseases (e.g., lupus) or brain injuries (e.g., brain tumor or stroke) can develop chorea. Some endocrine (hormonal) and metabolic disorders, such as hypothyroidism, can cause chorea.
Various medications, including those used to treat Parkinson's disease, can cause chorea as a side effect.
Diagnosis and Treatment
Doctors diagnose chorea by observation of the symptoms. It can be more challenging to find the cause. Imaging and blood tests can help.
If they think you have chorea, your doctor will also ask you what medications you are taking.
After your doctor determines the cause, they’ll decide if you need to get treatment. This is because chorea may go away without treatment in some cases. Sometimes, doctors treat the underlying disorder or adjust the medications that are causing chorea.
Your doctor will also prescribe drugs to help control the movements. Most of such drugs block the action of dopamine.
Even though doctors may use brain surgery to treat chorea, it can cause serious complications.
Deep brain stimulation is another technique being tested as a treatment for chorea. It is already used for some people with Parkinson's disease. Another possible treatment can include the use of cell transplants.
Chorea in Huntington’s Disease
Huntington's disease is the best-known cause of chorea. It is a rare disease, which affects only about one in 10,000 to 20,000 people. It differs from other conditions causing chorea because it is incurable and eventually leads to death.
Huntington's disease — originally known as Huntington's chorea — happens when certain parts of your basal ganglia degenerate.
The first sign of this disease is movement problems, which usually begin between the ages of 35 and 40 years. The related mental problems start about the same time as the movement problems, but they may not be as obvious.
Genetics of Huntington’s Disease
Children who have a parent with Huntington's disease have a 50% chance of getting it. Scientists discovered the defective gene that causes this disease in 1993.
Today , you can get genetic testing for Huntington’s disease gene done in order to:
- Confirm a diagnosis of Huntington’s disease if you are showing the symptoms
- Learn if you’ll get the disease if your parents or other relatives have Huntington’s disease or a similar disease
- Learn via prenatal testing if your unborn baby will have the disease
Today, prenatal testing accounts for only about 1% of testing done for Huntington’s. In most cases, people whose baby is found to have the Huntington’s disease gene choose not to have children.
If you are interested in genetic testing for HD, get genetic counseling first. It can help you deal with the psychological impact of the test results.
