Huntington's disease is a genetic, progressive, neurodegenerative disorder characterized by the gradual development of involuntary muscle movements affecting the hands, feet, face, and trunk and progressive deterioration of cognitive processes and memory (dementia). Neurologic movement abnormalities may include uncontrolled, irregular, rapid, jerky movements (chorea) and athetosis, a condition characterized by relatively slow, writhing involuntary movements. Dementia is typically associated with progressive disorientation and confusion, personality disintegration, impairment of memory control, restlessness, agitation, and other symptoms and findings. In individuals with the disorder, disease duration may range from approximately 10 years up to 25 years or more. Life-threatening complications may result from pneumonia or other infections, injuries related to falls, or other associated developments.

Huntington's disease is transmitted as an autosomal dominant trait. The disease results from changes (mutations) of a gene known as "huntington" located on the short arm (p) of chromosome 4 (4p16.3). In those with the disorder, the huntington gene contains errors in the coded "building blocks" (nucleotide bases) that make up the gene's instructions. The gene contains abnormally long repeats of coded instructions consisting of the basic chemicals cytosine, adenine, and guanine (CAG trinucleotide repeat expansion). The length of the expanded repeats may affect the age at symptom onset. The specific symptoms and physical features associated with Huntington's disease result from degeneration of nerve cells (neurons) within certain areas of the brain (e.g., basal ganglia, cerebral cortex).

Chorea symptoms usually depend upon the condition causing it. A common symptom is “milkmaid’s grip.” People with this condition don’t have coordinated hand muscles and will squeeze and release their hand, as if milking. Another symptom is involuntarily sticking out the tongue.

Chorea movements can be fast or slow. A person may appear to be writhing in Pain and have no bodily control. These movements have also been called dance-like or similar to piano playing.

Conditions associated with chorea and its symptoms include:

Huntington’s disease

Huntington’s disease is an inherited disease. It causes the breakdown of nerve cells in your brain. People with Huntington’s disease can experience chorea symptoms such as involuntary jerking or writhing. Milkmaid’s grip is also a common symptom.

Chorea is more common in people with adult-onset Huntington’s disease. Over time, symptoms may get worse, and movements may affect the legs and arms.

Chorea-acanthocytosis

This condition is a very rare genetic disorder. It’s characterized by misshapen red blood cells. It causes neurological abnormalities and affects brain functioning.

Chorea for this condition commonly involves:

• abnormal arm and leg movements
• shoulder shrugs
• pelvic thrusts

It can also involve rapid, purposeless movements of the face.

People with this form of chorea can also exhibit dystonia. This is characterized by involuntary muscle contractions of the mouth and face, such as:

• teeth grinding
• involuntary belching
• drooling or spitting
• lip and tongue biting
• difficulty with speech or communication
• difficulty swallowing
• vocal tics, such as grunting, involuntary speaking, or slurred speech

In addition to chorea and dystonia, this condition may cause:

• seizures
• neuropathy
• loss of sensation
• muscle weakness
• behavioral and personality changes

Sydenham’s chorea

Sydenham’s chorea mainly affects children and adolescents. It follows a streptococcal infection. It can also be a complication of rheumatic fever.

This type of chorea mainly affects the:

• face
• arms
• hands

It can impede voluntary movements, making it difficult to perform basic tasks such as getting dressed or feeding yourself.

It can also lead to:

• frequently dropping or spilling items
• abnormal gait
• muscle weakness
• slurred speech
• diminished muscle tone

People with this chorea type often display milkmaid grip. Another common symptom is called “harlequin tongue.” When a person with this symptom tries to stick their tongue out, the tongue pops in and out instead.

Chorea is associated with several additional causes, some temporary and some chronic. These causes include:

• AIDS
• genetic conditions, such as Huntington’s disease
• immune conditions, such as systemic lupus erythematosus
• infection-related conditions, such as Sydenham’s chorea
• medications, including levodopa and neuroleptics
• metabolic or endocrine disorders, including hypoglycemia
• pregnancy, known as chorea gravidarum

Treatment of chorea depends on the type of chorea you have. It aims to treat the underlying condition, which will help with chorea symptoms.

For example, Sydenham’s chorea may be treatable with antibiotics. Huntington’s disease chorea can be treated with antipsychotic drugs, as well as other medications.

Chorea due to Parkinson’s disease has no cure, but symptoms can be managed.

Medications

Most medications for chorea affect dopamine. Dopamine is a neurotransmitter, or brain chemical, that controls movement, thinking, and pleasure in your brain, among other things.

Many movement disorders are associated with dopamine levels. These disorders include Parkinson’s disease and restless legs syndrome.

Some medications block dopamine receptors so your body can’t use the chemical. Many of these are antipsychotic drugs that seem to reduce chorea. These drugs, which doctors can prescribe for off-label use, include:

• fluphenazine (Prolixin)
• haloperidol (Haldol)
• olanzapine (Zyprexa)
• quetiapine (Seroquel)
• risperidone (Risperdal)

Other drugs reduce the amount of dopamine in the brain, such as reserpine and tetrabenazine (Xenazine). Medications known as benzodiazepines, such as clonazepam (Klonopin), may also help to reduce chorea.

Anticonvulsants, which reduce spontaneous movements, can also reduce chorea symptoms.

Surgeries

Deep brain stimulation is a surgical approach that shows promise for chorea treatment. This treatment involves implanting electrodes in your brain to regulate nerve impulses.

If chorea doesn’t respond to medications, your doctor may recommend deep brain stimulation. This procedure does not cure chorea, but it can reduce its symptoms.

Home care

Chorea increases a person’s likelihood for falls. Home care measures include installing nonslip surfaces on stairs and in bathrooms to prevent injury. Talk to your doctor about other ways to modify your home for safety.

People with a history of rheumatic fever are more likely to experience chorea. Other risk factors are related to risks for a specific disease.

For example, Huntington’s disease is a hereditary disorder that may cause chorea. A person with a parent who has Huntington’s disease has a 50 percent chance of inheriting the disease.

The outlook for chorea depends on the condition causing it. Antibiotics can cure Sydenham’s chorea. While there’s no cure for Huntington’s disease, it can be managed.

Women with chorea gravidarum during pregnancy typically stop having symptoms within 6 weeks after giving birth.

People with metabolic or endocrine-related chorea typically stop having symptoms once a doctor treats the imbalance.

Whatever the condition causing chorea, your doctor will develop a treatment plan to help you manage your symptoms.