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Dystonia is characterized by long-lasting (sustained) involuntary muscle contractions that may force people into abnormal positions—for example, causing the entire body, the trunk, limbs, or neck to twist.
Dystonia may result from a genetic mutation, a disorder, or a drug.
Muscles in the affected part of the body contract, distorting the position of that body part.
Doctors base the diagnosis on symptoms and results of a physical examination.
The cause is corrected if possible, but if not, drugs, such as mild sedatives, levodopa plus carbidopa, and botulinum toxin, may help relieve symptoms.
Dystonia seems to result from overactivity in several areas of the brain—the basal ganglia, thalamus, cerebellum, and cerebral cortex.
Locating the Basal Ganglia
The basal ganglia are collections of nerve cells located deep within the brain. They include the following:
The basal ganglia help smooth out muscle movements and coordinate changes in posture.
Dystonia may result from
Antipsychotic drugs and some drugs used to relieve nausea can cause various types of dystonia, including shutting of the eyelids, twisting of the neck (spasmodic torticollis) or back, grimacing, puckering of the lips, protrusion of the tongue, and writhing of the arms or legs.
Causes of Dystonia
Dystonias may affect
Dystonias that affect one or several body parts typically start after age 20 to 30, but they sometimes start earlier.
Initially, contractions (spasms) may occur periodically or only during stress. Certain movements of the affected body part may trigger the spasms, which may disappear during rest. Over days, weeks, or many years, spasms may become more frequent and may continue during rest. Eventually, the affected body part may remain distorted, sometimes in a painful position. As a result, people may be severely disabled.
The following are examples of focal or segmental dystonias:
Blepharospasm: This dystonia affects mainly the eyelids. The eyelids are repeatedly and involuntarily forced shut. Occasionally, only one eye is affected at first, but ultimately, the other eye is also affected. It usually begins as excessive blinking, eye irritation, or extreme sensitivity to bright light. Many people with blepharospasm find ways to keep their eyes open, such as yawning, singing, or opening the mouth wide. These techniques become less effective as the disorder progresses. Blepharospasm can severely impair vision if the eyes cannot be kept open as needed.
Spasmodic torticollis: Torticollis specifically affects the muscles of the neck. Spasmodic torticollis, also called adult-onset cervical dystonia, is the most common form of cervical dystonia, which is the most common dystonia of the neck.
Spasmodic dysphonia: The muscles of the vocal cords, which control speech, contract involuntarily. Speech may be impossible or may sound strained, quavery, hoarse, whispery, jerky, creaky, staccato, or garbled and be difficult to understand.
Occupational dystonias: These dystonias, also called task-specific dystonias, affect one part of the body and often result from overuse. For example, golfers may have involuntary muscle spasms in the hands and wrists (called the yips). The yips may make putting nearly impossible. What is supposed to be a 3-foot putt can become a 15-foot putt when a golfer loses control because of the yips. Similarly, musicians, especially concert pianists, may have bizarre spasms of the fingers, hands, or arms that prevent them from performing. Musicians who play wind instruments may have spasms of the mouth. Persistent writer’s cramp may be dystonia.
Meige disease: This dystonia combines involuntary blinking with jaw grinding and grimacing. Thus, it is also called blepharospasm-oromandibular dystonia. (“Blepharo” refers to the eyelids, “oro” refers to the mouth, and “mandibular” refers to the jaw.) It usually begins in late middle age.
These dystonias affect the trunk plus two different body parts. They include the following:
Primary generalized dystonia: This rare dystonia, also called idiopathic torsion dystonia, is progressive and often hereditary. In many cases, specific genetic mutations have been identified. The gene most commonly affected is the DYT1 gene. The resulting dystonia is called DYT1 dystonia. Involuntary movements result in sustained, often bizarre postures. Typically, symptoms begin during childhood, often with turning the foot in during walking. The dystonia may affect only the trunk or a leg but often affects the whole body, ultimately confining children to a wheelchair. When this dystonia develops in adults, it usually begins in the face or arms and usually does not affect other parts of the body. Mental function is not affected.
Dopa-responsive dystonia: This rare form of dystonia is hereditary. Symptoms usually begin during childhood. Typically, one leg is affected first. As a result, children tend to walk on tiptoes. Symptoms worsen at night. Walking becomes progressively more difficult, and both arms and legs are affected. However, some children have only mild symptoms, such as muscle cramps after exercise. Sometimes symptoms appear later in life and resemble those of Parkinson disease. Movements may be slow, balance may be difficult to maintain, and a tremor may occur in the hands during rest. Symptoms lessen dramatically when people are given low doses of levodopa. If levodopa relieves the symptoms, the diagnosis is confirmed.
Doctors usually diagnose dystonias based on symptoms and results of a physical examination.
If doctors suspect that a disorder is causing the dystonia, they may do tests to identify the cause, such as computed tomography (CT) or magnetic resonance imaging (MRI).
Correcting or eliminating the cause of dystonia, if known, usually reduces the spasms. For example, drugs used to treat multiple sclerosis may reduce spasms related to that disease. When dystonia is due to use of an antipsychotic drug, promptly taking diphenhydramine by injection or by mouth usually stops the spasms quickly, and the antipsychotic is stopped.
For generalized dystonia, an anticholinergic drug (such as trihexyphenidyl or benztropine) is most commonly used. These drugs reduce spasms by blocking specific nerve impulses involved in causing the spasms. However, anticholinergic effects of these drugs also include confusion, drowsiness, dry mouth, blurred vision, dizziness, constipation, difficulty urinating, and loss of bladder control, which are troublesome, especially in older people. A benzodiazepine (a mild sedative) such as clonazepam, baclofen (a muscle relaxant), or both are also usually given. Baclofen may be given by mouth or by a pump implanted in the spinal canal.
If generalized dystonia is severe or does not respond to drugs, deep brain stimulation may be done. For this procedure, tiny electrodes are surgically implanted in the basal ganglia (collections of nerve cells that help smooth out muscle movements). The electrodes send small amounts of electricity to the specific area of the basal ganglia that causes dystonia and thus help lessen symptoms.
Some people, especially children with dopa-responsive dystonia, improve dramatically when they are treated with levodopa plus carbidopa.
If one or a few body parts are affected, botulinum toxin (a bacterial toxin used to paralyze muscles or to treat wrinkles) is injected into the overactive muscles. Botulinum weakens the muscle contraction but does not affect the nerves. These injections are particularly useful for blepharospasm and spasmodic torticollis. However, injections must be repeated about every few months. The toxin becomes less effective over time because when repeatedly exposed to it, the body produces antibodies that inactivate the toxin. If the affected muscles are tiny or deep in the body, electromyography (stimulating muscles and recording their electrical activity) may be done to identify the muscles to be injected.
Physical therapy helps some people, especially those who are treated with botulinum.
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