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disorders affecting the basal ganglia
The basal ganglia are a group of structures within the brain that help with movement. 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 a group of small structures inside the brain. One of the main jobs of these structures is to help with movement. For instance, this part of the brain helps a person start to move. It also affects how fast the person can perform the movement. The basal ganglia are also thought to play a role in thinking and emotions.
What are the signs and symptoms of the condition?
Symptoms and signs depend on the specific disorder, but may include:
Other signs and symptoms are also possible.
- tremor, an unintentional, repeated movement. The movement has a certain rhythm and speed to it and is usually noticed in an arm or leg. Tremors usually occur when the person is sitting still, and may go away with movement.
- difficulty starting and continuing movement. An affected person may move very slowly, and feel as if he or she is stuck in slow motion.
- 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.
- chorea, which describes rapid, jerky, forcible, uncontrollable movements. These are usually noticed in the arms, legs, or face
- 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 also usually noticed in the arms or legs
- 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.
- emotional or personality problems, such as depression, inappropriate behaviour, or paranoia
- an inability to think clearly, concentrate, or recall
What are the causes and risks of the condition?
Many disorders can affect this part of the brain, including:
- Parkinsonism or Parkinson's disease, a condition that tends to slowly get worse and often has no known cause. 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.
- 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.
- 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.
- 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 arteriosclerosis. The specific effects of a stroke depend on the part of the brain that is affected.
- Wilson disease, an inherited condition that causes movement and liver problems. It also often causes personality and emotional changes.
- Creutzfeldt-Jacob disease, thought to be related to mad cow disease. This can be genetic or due to exposure to contaminated materials. This condition usually gets worse quickly and may cause any of the signs and symptoms of basal ganglia disorders.
- medications, especially those used to treat psychosis. Examples include haloperidol and risperidone.
- 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.
- kernicterus, a condition that may occur in newborns as a rare complication of jaundice, or yellow eyes and skin
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 medications, toxins, or contaminated material could help prevent some cases, but is often not possible.
How is the condition diagnosed?
Diagnosis is usually based on the history and physical examination. 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 counselling can be helpful to some couples. The infection that causes rheumatic fever is often contagious. But, those who catch it usually don't develop a basal ganglia disorder.
What are the treatments for the condition?
Medications are often used to control symptoms. Surgery may be an option for those who do not respond to medications. If the disorder is caused by a medication, stopping the medication reverse the symptoms. Physiotherapy, 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. Medications may cause allergic reactions, stomach upset, or other side effects. Any surgery carries a risk of bleeding or infections.
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 medications, may go away completely and need no further monitoring or treatment.
How is the condition monitored?
A person taking medications needs close monitoring for side effects and possible loss of effect of the medications over time.
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 7/11/2004
Potential conflict of interest information for reviewers available on request