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The basal ganglia are groups of nerve cells within the brain that help manage movement of the body. Any condition that affects the function of these structures is a basal ganglia disorder.

What is going on in the body?

The basal ganglia are groups of small clusters of cells deep within the brain. The way in which the brain controls movement is complicated and not completely understood at this time. The basal ganglia are only one component of movement production. Simply put, the basal ganglia are the gate-keeper of movement. A disorder of the basal ganglia can either lead to too much movement or too little movement.

What are the signs and symptoms of the condition?

Symptoms and signs depend on the specific disorder but may include:

• athetosis, which describes the inability to keep a muscle group in one position. A person with this condition has continuous, slow, writhing movements. These are usually noticed in the arms or legs.
• chorea, which is characterized by rapid, brief, jerky, involuntary movements. These are also usually noticed in the arms, legs, or face.
• difficulty starting and continuing movement. An affected person may move very slowly and feel as if he or she is stuck in slow motion.
• emotional or personality problems, such as depression, inappropriate behavior, or paranoia
• dementia or memory dysfunction
• increased muscle tone, or having a muscle that seems as though it is flexed. This occurs even when the person is not trying to flex or use the muscle.
• tremor, an unintentional, rhythmical, repetitive movement of the head, hands, arms or legs. Tremors usually occur when the person is sitting still and go away with movement.
• unstable posture, which means that the person is often unsteady on his or her feet. The person may have an unusual way of walking, which is known as an abnormal gait.

Other signs and symptoms are also possible.

What are the causes and risks of the condition?

Many disorders can affect this part of the brain, including:

• cerebral palsy, a type of brain damage in young children. This is often present at birth and can cause many different movement problems or learning difficulties.
• Creutzfeldt-Jacob disease. This condition, caused by an abnormal protein known as a "prion", can be genetic, or due to exposure to contaminated human or animal substances, or occur for no known reason. This condition usually gets worse quickly and may cause any of the signs and symptoms of basal ganglia disorders.
• Huntington disease or chorea, a genetic condition that also slowly gets worse. It commonly causes chorea and athetosis. Personality, emotional, and thinking changes are also common.
• kernicterus, a condition that may occur in newborns as a rare complication of jaundice, or yellow eyes and skin
• medicines, especially those used to treat psychosis. Examples include haloperidol and risperidone.
• Parkinson disease (Parkinsonism), a condition resulting from biochemical abnormalities in the brain neurotransmitters. Parkinson disease often develops for no known reason, and tends to slowly get worse over time. Affected people commonly develop a tremor at rest, trouble starting and continuing movements, a blank expression on the face, thinking changes, and an abnormal gait.
• stroke, which is brain damage that is caused by a lack of oxygen in the brain. It is often due to clogging of the arteries, called atherosclerosis. The specific effects of a stroke depend on the part of the brain that is affected.
• Sydenham chorea, a type of chorea that usually occurs in children with rheumatic fever. This is a rare complication of a group A streptococcus infection.
• Wilson disease, an inherited condition that causes movement and liver problems. It also often causes personality and emotional changes.

Other disorders can also affect this part of the brain. Sometimes the cause cannot be found.

What can be done to prevent the condition?

Most cases cannot be prevented. Streptococcal infections are treated with antibiotics to prevent cases due to rheumatic fever. Newborns with severe jaundice can be treated to prevent kernicterus. Avoidance of medicines, toxins, or contaminated material could help prevent some cases, but this is often not possible.

How is the condition diagnosed?

Diagnosis is usually based on the medical history and physical exam. Figuring out the cause also often requires further tests. These may include blood tests, cranial CT scan, and cranial MRI scan. Other special testing may be needed in some cases.

What are the long-term effects of the condition?

Many of these conditions, such as Parkinson and Huntington disease, may lead to death even with treatment. A person will gradually have more and more trouble moving, thinking, and performing self-care. Other causes, such as Sydenham chorea, may go away and have no long-term effects.

What are the risks to others?

These disorders are generally not contagious. Some, such as Huntington and Wilson disease, may be passed on to one's children. Genetic counseling can be helpful to some couples. The infection that causes rheumatic fever is often contagious. However, those who have rheumatic fever do not usually develop a basal ganglia disorder.

What are the treatments for the condition?

Medicines are often used to control symptoms. Surgery may be an option for those who do not respond to medicine. If the disorder is caused by a medicine, stopping the medicine may reverse the symptoms. Physical therapy, occupational therapy, and speech therapy may help a person to stay independent longer.

What are the side effects of the treatments?

Side effects depend on the treatment used. Medicines may cause allergic reactions, stomach upset, or other side effects. Any surgery can be complicated by bleeding, infection, or reactions to anesthesia.

What happens after treatment for the condition?

Even if relief of symptoms occurs, the disorder often gets worse. In this case, changes in therapy can be tried. Many times people die from complications such as pneumonia. Some cases, such as those due to medicines, may go away completely and need no further monitoring or treatment.

How is the condition monitored?

A person taking medicines needs close monitoring for side effects and possible loss of effect of the medicines over time.