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The Merck Manual--Second Home Edition logo
 
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Chapter 91. Movement Disorders
Topics: Introduction | Myoclonus | Tremor | Parkinson's Disease | Progressive Supranuclear Palsy | Shy-Drager Syndrome | Tics | Chorea and Athetosis | Huntington's Disease | Dystonia | Coordination Disorders
 
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Huntington's Disease

Huntington's disease (Huntington's chorea) is a hereditary disease that begins with occasional jerks or spasms and gradual loss of brain cells and that progresses to more pronounced involuntary movements (chorea and athetosis) and mental deterioration.

Huntington's disease affects fewer than 1 of 10,000 people. Both sexes are affected equally. The gene for Huntington's disease is dominant; therefore, children of a person who has this disease have a 50% chance of developing it (see Section 1, Chapter 2). Because Huntington's disease begins subtly, the exact age at which it begins is difficult to determine. Symptoms usually become obvious between the ages of 35 and 40.

Symptoms

During the early stages of Huntington's disease, people can blend the spontaneous abnormal movements into intentional ones so that the abnormal movements are barely noticeable. However, with time, the movements become more obvious. People grimace, flick the limbs, and blink more often. Muscles become uncoordinated, and movements slow. Eventually, the entire body is affected, making walking impossible and eating, speaking, dressing, and sitting still nearly impossible.

Mental changes are subtle at first. People with the disease may gradually become irritable and excitable; they may lose interest in their usual activities. They may be unable to control their impulses, losing their temper, having fits of despondency, or becoming promiscuous. As the disease progresses, people may behave irresponsibly and often wander aimlessly. Over years, they may lose their memory and the ability to think rationally. They may become severely depressed and attempt suicide. In advanced disease, almost all functions are impaired, and dementia is severe. Full-time assistance or nursing home care is needed. Death, often precipitated by pneumonia or by a fall, usually occurs 13 to 15 years after symptoms begin.

Diagnosis

Huntington's disease may be difficult to recognize in the early stages because symptoms are subtle. The disease may be suspected based on symptoms and a family history. Doctors should be told about relatives who have had mental problems or have been diagnosed as having a neurologic or psychiatric disorder (such as Parkinson's disease or schizophrenia), because Huntington's disease may have been present but was not diagnosed. Computed tomography (CT) or magnetic resonance imaging (MRI) can detect wasting away (atrophy) of the basal ganglia, which is characteristic of the disease.

The disease can be easily diagnosed using genetic testing. However, whether people who have a family history of the disease but no symptoms should be tested is controversial. Such people should undergo genetic counseling before genetic testing.

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Treatment

No cure exists for Huntington's disease. However, drugs, such as the sedative chlorpromazine, the antipsychotic haloperidol, and the antihypertensive reserpine, can help relieve symptoms and control behavior.

People with Huntington's disease should establish advance directives, indicating what kind of medical care they want at the end of life (see Section 1, Chapter 9).

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