MSD Manual

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Alex Rajput

, MD, University of Saskatchewan;

Eric Noyes

, MD, University of Saskatchewan

Reviewed/Revised Feb 2024
Topic Resources

Dystonias are involuntary muscle contractions, which may be long-lasting (sustained) or come and go (intermittent). Dystonias 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 medication.

  • Muscles in the affected part of the body contract, distorting the position of that body part, and stay contracted for many minutes to hours.

  • Doctors base the diagnosis on symptoms and results of a physical examination.

  • The cause is corrected if possible, but if not, medications, such as mild sedatives, levodopa plus carbidopa, and botulinum toxin, may help relieve symptoms.

Causes of Dystonia

Dystonia seems to result from overactivity in several areas of the brain:

  • Basal ganglia, which are collections of nerve cells that help initiate and smooth out voluntary muscle movements, suppress involuntary movements, and coordinate changes in posture

  • Thalamus, which organizes messages about muscle movements to and from the cerebral cortex

  • Cerebellum, which coordinates the body’s movements, helps the limbs move smoothly and accurately, and helps maintain balance

  • Cerebral cortex (the convoluted outer layer of tissue of the cerebrum—the gray matter)

Locating the Basal Ganglia

The basal ganglia are collections of nerve cells located deep within the brain. They include the following:

  • Caudate nucleus (a C-shaped structure that tapers to a thin tail)

  • Putamen

  • Globus pallidus (located next to the putamen)

  • Subthalamic nucleus

  • Substantia nigra

The basal ganglia help initiate and smooth out muscle movements, suppress involuntary movements, and coordinate changes in posture.

Locating the Basal Ganglia

Dystonia may result from

  • A genetic mutation (called primary dystonia)

  • A disorder or medication (called secondary dystonia)


Types and Symptoms of Dystonia

Muscles in the affected part of the body contract, distorting the position of that body part. Muscles stay contracted for many minutes to hours or may contract and relax unpredictably.

Dystonias may affect

  • One part of the body (focal dystonias)

  • Two or more parts of the body that are next to each other (segmental dystonias)

  • Two or more parts that are not next to each other (multifocal dystonias)

  • The trunk plus two different body parts (generalized dystonias)

Focal and segmental dystonias

Focal dystonias affect one body part. They typically start after age 20 to 30, but they sometimes start earlier.

Segmental dystonias affect several body parts that are next to each other.

Initially, contractions (spasms) may occur periodically or only during a particular activity. 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 Blepharospasm Blepharospasm is a spasm of the muscles around the eye. The cause of blepharospasm is often unknown. It affects women more than men and tends to occur in families. It can sometimes be caused... read more : 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 Cervical Dystonia Cervical dystonia is characterized by long-lasting (chronic sustained) involuntary contractions or periodic, intermittent spasms of the neck muscles, causing the neck to turn in different ways... read more : Torticollis specifically affects the muscles of the neck. Spasmodic torticollis, also called adult-onset cervical dystonia, is the most common form of dystonia of the neck (cervical dystonia).

  • 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.

Generalized dystonias

These dystonias affect the trunk plus two different body parts. The gene for these disorders is often dominant. In these cases, having only one copy of the abnormal gene, inherited from one parent, is sufficient to cause the disease. Generalized dystonias include the following:

  • Primary generalized dystonia: This rare 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. Some people who have the gene have no symptoms or have only a tremor. In people with the most severe form, involuntary movements result in sustained, often varied abnormal postures. Postures can become almost permanent (fixed). 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 the child 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 of dopa-responsive dystonia 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 Symptoms Parkinson disease is a slowly progressive degenerative disorder of specific areas of the brain. It is characterized by tremor when muscles are at rest (resting tremor), increased muscle tone... read more . 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.

Did You Know...

  • Medications used to treat nausea or psychosis sometimes cause abnormal sustained muscle contractions (dystonias).

  • Botulinum toxin, also used to treat facial wrinkles, is used to treat some dystonias.

Diagnosis of Dystonia

  • A doctor's evaluation

  • Sometimes tests to identify the cause

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).

Treatment of Dystonia

  • Correction or elimination of the cause

  • Medications

  • Sometimes deep brain stimulation

  • Physical therapy

Correcting or eliminating the cause of dystonia, if known, usually reduces the spasms. For example, medications used to treat multiple sclerosis Multiple Sclerosis (MS) In multiple sclerosis, patches of myelin (the substance that covers most nerve fibers) and underlying nerve fibers in the brain, optic nerves, and spinal cord are damaged or destroyed. The cause... read more may reduce spasms related to that disease. When dystonia is due to use of an antipsychotic medication, promptly taking diphenhydramine by injection or by mouth usually stops the spasms quickly, and the antipsychotic is stopped.

For generalized dystonia, an anticholinergic Anticholinergic: What Does It Mean? Anticholinergic: What Does It Mean? medication (such as trihexyphenidyl or benztropine) is most commonly used. These medications reduce spasms by blocking specific nerve impulses involved in causing the spasms. However, these medications may also cause confusion, drowsiness, dry mouth, blurred vision, dizziness, constipation, difficulty urinating, and loss of bladder control, which are troublesome, especially in older adults. 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 medications, deep brain stimulation may be done. For this procedure, tiny electrodes are surgically implanted in the basal ganglia (collections of nerve cells that help initiate and smooth out voluntary 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.

For focal or segmental dystonias or for generalized dystonia that affects mainly one body part, the treatment of choice is botulinum toxin (a bacterial toxin used to paralyze muscles or to treat wrinkles). It 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 3 to 4 months because botulinum toxin becomes less effective over time. In a few people who are repeatedly given to botulinum injections, the body produces antibodies that inactivate the toxin. If the affected muscles are tiny or deep in the body, electromyography Electromyography and Nerve Conduction Studies Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Imaging tests commonly used to diagnose nervous system (neurologic) disorders... read more Electromyography and Nerve Conduction Studies (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 toxin.

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