What is Chorea?
The World Federation of Neurology’s Committee on Classification defines chorea as a condition where a person experiences excess, sudden movements that aren’t repetitive and have no specific timing or distribution. They’re sudden and can differ in how severe they are. They can range from restlessness and exaggerated gestures to uncontrolled movements that disrupt daily functioning, resembling a dance. This is why the term ‘chorea’, which is similar to ‘choreography’, is used.
Chorea is often accompanied by athetosis and ballism. Athetosis is a slower version of chorea, marked by twisting or writhing movements. On the other hand, ballism is an extremely severe form of chorea, with violent, uncontrollable limb movements that can be compared to flinging. Usually, these movements affect one side of the body, but in rare cases, they can occur on both sides.
What Causes Chorea?
Chorea is a type of movement disorder, often associated with Huntington’s disease, that can cause uncontrollable, irregular movements. There are many diseases besides Huntington’s that can result in chorea, like spinocerebellar ataxia subtypes, Wilson’s disease, Sydenham chorea, and conditions affecting the basal ganglia – a part of the brain involved in the control of voluntary movement.
When we look at brain scans of patients with chorea, we often see shrinkage of a brain part called the caudate nucleus. Huntington’s disease, a genetic condition causing chorea, is due to a mutation in the gene known as HTT, located on chromosome 4.
However, chorea can also be triggered by many other factors:
* It can be caused by endocrine and metabolic conditions, such as low blood sugar, overactive thyroid, kernicterus (a severe form of jaundice), and low magnesium levels.
* Infectious diseases like rheumatic fever, syphilis, a brain inflammation called subacute sclerosing panencephalitis, Lyme disease, toxoplasmosis, HIV, and heart infection (endocarditis) can also result in chorea.
* Certain medications like levodopa (used in Parkinson’s disease treatment), birth control pills, antipsychotics, antihistamines, cocaine, amphetamine, and antidepressants (tricyclics) can induce chorea.
* Toxins such as carbon monoxide, mercury, and alcohol can also lead to chorea.
* Neurologic conditions, like stroke and migraine.
* Vascular conditions, such as polycythemia, Churg Strauss syndrome, systemic lupus erythematosus (SLE), Behcet’s syndrome, and multiple sclerosis, may cause chorea.
* Lastly, both primary brain tumors and metastatic lesions (spread of cancer from other parts of the body to the brain) can cause chorea.
Risk Factors and Frequency for Chorea
Chorea is a condition that can happen in a variety of different disorders. While the incidence, or occurrence, of chorea in specific disorders is known, we don’t have complete data for its global incidence. Below are some disorders in which chorea is common:
- In Huntington disease, a neurodegenerative disorder that’s typically inherited, there are about 5-10 cases per 100,000 people in the US, mainly seen in Caucasians. However, it’s also appearing in people who have migrated and settled in South and Central America.
- Wilson disease impacts multiple systems in the body and is inherited. It has a prevalence of about 30 cases per million people.
- Benign hereditary chorea is a rare disorder that’s also inherited. It occurs in approximately 1 out of every 500,000 people.
Chorea can happen at any age. For younger people, the most common triggers are infections, physical injuries, and inflammatory conditions.
For a specific type called Huntington chorea, most people start showing signs in their 40s or 50s, and the condition worsens over time. It’s unusual for this condition to appear before someone turns 30. If it does occur early, it’s usually because the affected person got the gene from their father. If the onset is late, it’s likely that the gene came from the mother.
Signs and Symptoms of Chorea
Chorea is a health condition where patients experience uncontrolled movements, making it hard for them to maintain a steady posture or hold a position. One sign of this can be seen when a patient tries to grip an object, they will involuntarily release and squeeze it repeatedly. They also often drop objects.
The condition can affect both close-to-body (proximal) and farther-from-body (distal) muscles. While most patients have normal muscle strength, some may have weaker muscle tone, also known as hypotonia.
The most common reason people seek medical help for this condition is because of excessive unintended movements of parts of the body. These irregular “choreiform” movements can be easily seen. Other signs can include problems with controlling the tongue’s movement, where a patient can’t keep their tongue stuck out and it moves in and out of the mouth. An MRI scan can show the typical signs of chorea, such as shrinking of the caudate area of the brain, shown by the widening of the brain’s lateral ventricles. Further into the disease, patients may show changes in their thinking and behavior.
Testing for Chorea
If a doctor suspects someone has Huntington’s disease, they may use various methods to confirm their diagnosis. One method might be genetic testing, as Huntington’s is a hereditary condition. Other examinations could include brain imaging scans, such as computed tomography (CT) or magnetic resonance imaging (MRI), which help doctors see any changes or damage in the brain.
In addition, a psychiatrist might look for issues in a patient’s cognitive, behavioral, and functional areas, as Huntington’s can also affect these aspects. It is also crucial to ask about suicidal thoughts, as they can be prevalent among people with Huntington’s disease.
Sometimes, a positron emission tomography (PET) scan is used. This scan can help doctors evaluate conditions such as Huntington’s chorea and neuroacanthocytosis. These conditions often show decreased activity in certain parts of the brain like the putamen and caudate nucleus. However, this decrease in activity won’t always appear in individuals with benign hereditary chorea – a milder, non-progressive form of the disease.
Treatment Options for Chorea
While there’s currently no cure for this disease, the symptoms can be managed and quality of life can be improved. One key aspect is developing a strong support system for the patient because as the disease progresses, they will need expert caregiving. Proper nutrition is also critical because swallowing can become difficult. Tetrabenazine is a medication that’s been approved to manage the symptom of involuntary, jerky movements called chorea.
In terms of medical treatment, most patients receive drugs called neuroleptics, which stop certain chemicals in the brain like dopamine from working. Other medications, including valproate, clonazepam, and gabapentin, that affect another brain chemical called GABA, are also used. Two potential treatments showing promise in animal studies are minocycline, an antibiotic, and CoQ10, a natural antioxidant. They may help with chorea, but in some cases, chorea related to heart transplants responds to steroids, and for other patients with chorea caused by rheumatic fever, a blood-cleansing procedure called plasmapheresis may shorten the course of the symptom. However, it’s important to note that while these treatments can reduce chorea in some patients, they also carry strong side effects.
Surgery is another option but is used less commonly. Over the recent decade, a surgery called deep brain stimulation (DBS) has been explored and might be useful in some patients. DBS is performed by placing electrodes in a specific part of the brain. While there are reports that DBS works and eases chorea in some patients, it’s still experimental, doesn’t work for everyone, and can lead to complications.
Another experimental surgical treatment is neural cell transplantation, which has been trialled in a small number of patients with Huntington’s chorea, a type of involuntary movement disorder. But again, not all patients have seen improvement with this approach.
What else can Chorea be?
- Huntington’s disease
- Lesch-Nyhan syndrome
- Lyme disease
- Multiple system atrophy
- Neuroacanthocytosis
- Surgery for torticollis in children
- Ramsay Hunt syndrome
- Striatonigral degeneration
- Tourette’s syndrome
- Viral encephalitis
These are various health conditions or procedures that doctors might consider when diagnosing and treating neurological disorders.
What to expect with Chorea
The outlook for people with chorea, a condition causing irregular, spontaneous movements, largely depends on its root cause. Many individuals with Huntington’s chorea face a grim prognosis and usually have a shortened lifespan. Those with neuroacanthocytosis, another cause of chorea, are similarly affected.
Severe involuntary movements can lead to localized injuries or a serious condition called rhabdomyolysis, where damaged muscle tissue breaks down rapidly.
In some cases, patients with neuroacanthocytosis or those with tongue dystonia, a condition that causes involuntary muscle contractions, may experience problems with swallowing. This can lead to weight loss and recurring bouts of aspiration pneumonia, a lung infection caused by inhaling food, stomach acid or saliva into the lungs. In extreme cases, these complications can even result in death.