BRAIN & NERVOUS SYSTEM Movement Disorders • Parkinson's disease • Essential tremor • Tourette syndrome • Dystonia • Myoclonus

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Dystonia is a neurological disorder causing involuntary, sustained muscle contractions that result in repetitive movements, twisting and abnormal postures. An estimated 300,000 people in North America have dystonia.

Primary treatments for dystonia alleviate symptoms by adjusting movement-related nerve signals or temporarily immobilizing targeted muscles. In more severe cases, surgery may be used to disable or regulate certain brain regions or nerves.

Your doctor may refer to certain classifications of dystonia to distinguish how it affects your body:

• Focal dystonia is limited to muscles in a specific region: a single limb, eyelids, jaw and tongue, vocal cords, or neck.
• Segmental dystonia affects two or more parts of your body adjacent to each other.
• Multifocal dystonia affects two or more regions not adjacent to each other.
• Generalized dystonia affects all or nearly all of your body.
• Hemidystonia affects only one side of your body.

For most people, symptoms begin in a single region, but they may spread. Sometimes, they may be linked to a specific action. For example, you may experience involuntary contractions in one leg when walking forward but not when running forward or walking backward.

Dystonia in a specific region usually progresses so that contractions are more frequent or not limited to a specific kind of action. It may also progress to other regions of the body. Rates of progression vary significantly, but symptoms usually plateau within a few years.

Stress, fatigue or anxiety may temporarily worsen symptoms. Dystonia may be less apparent when you're relaxed or your limbs are at rest, and the contractions usually cease when you're in a deep sleep.

The affected region of the body may provide clues to the progression of the disorder. When it begins in a leg, especially during childhood, dystonia is more likely to progress to generalized dystonia. When it begins in a single location in the upper body, it may progress to other regions, but it's not as likely to become generalized.

The age of onset itself offers clues to progression. If the disorder appears in childhood or early adolescence, it's quite likely to progress to generalized dystonia, but dystonias developing well into adulthood rarely generalize to the whole body.

The impact of dystonia on a person's quality of life varies depending on the part of the body affected and the severity of contractions. For example, dystonia of the eyelids, with rapid blinking or squinting, can be so severe as to make a person functionally blind. Dystonia of the neck muscles may cause severe pain. Dystonia of the jaw and tongue muscles may cause slurred speech or difficulty eating or swallowing. Severe dystonia in the limbs or the neck can result in contracture of tendons and permanent distortion in posture.

Some types of dystonia are limited to a specific, repetitive task. Common versions of this include writer's cramp or musician's cramp, the involuntary and often painful contraction of the hand and arm muscles used in writing or playing an instrument.

For a few people with dystonia, symptoms may go away or become extremely mild for a period of months or years, but the symptoms usually reappear.

The basal ganglia, a cluster of brain cells (neurons) deep within the brain, are involved with the initiation and regulation of movement. Most cases of dystonia are thought to reflect dysfunction within the basal ganglia or related brain networks. Some evidence suggests that abnormal sensory input from different regions of the body may also be a contributing factor or trigger for dystonia.

Your doctor may refer to a classification of dystonia based on cause: primary and secondary dystonia. Primary dystonia, which accounts for about half of all cases, has no connection to a specific disease process or injury in the brain. In other words, the regular mechanisms for initiating, regulating or transmitting nerve signals aren't working properly, but doctors can't point to some "outside" factor that's disrupting this process.

About 30 percent to 40 percent of children or adolescents who carry a mutation in a gene called DYT1 develop primary, generalized dystonia, but researchers haven't determined how this mutation leads to the disorder. Research suggests that other forms of primary dystonia in children and adults may also be linked to genetic factors.

Secondary dystonia can be linked to a specific injury in the brain caused by stroke, tumor, severe trauma, toxins or birth injury. Dystonia resulting from such injuries often progresses to hemidystonia. Some cases of secondary dystonia are caused by a malfunction in the production of a chemical messenger called dopamine. Dystonia may also be a symptom of other neurological diseases, such as Parkinson's disease or Wilson's disease.

Because early symptoms of dystonia are often mild, intermittent and linked to a specific activity, some people with dystonia have reported that at first they thought they were just imagining a problem. If you or someone you know is experiencing involuntary muscle contractions, a doctor visit is essential.

A diagnostic work-up will include a thorough assessment of your symptoms, usually by a neurologist. Your doctor will also take a complete medical history to account for dystonia in the family, previous head injury or stroke, exposure to toxins or drugs, or evidence of other potential secondary causes. Blood or urine tests may reveal the presence of toxins, and magnetic resonance imaging (MRI) may be used to identify tumors, lesions or evidence of stroke.

Your doctor may recommend genetic testing for children, adolescents and some adults to screen for the DYT1 mutation. If an individual with dystonia tests positive for the mutation or if there's no evidence of a secondary cause, your doctor will diagnose the disorder as primary dystonia.

Dystonia may significantly affect your mobility and your scope of daily activities. People with more widespread dystonia may be stigmatized by others who associate the symptoms of dystonia with a cognitive disability. All of these factors may lead to feelings of frustration, depression or anxiety.

The constant contraction of muscles is somewhat like a sustained workout. Therefore, dystonia can be exhausting, and fatigue can, in turn, exacerbate the symptoms.

A number of treatments or treatment combinations may alleviate symptoms of dystonia.

Dopa-responsive dystonia
Dopa-responsive dystonia is a secondary form of the disorder that often occurs in children and adolescents. It's caused by poor production of the messenger chemical dopamine. Individuals with this disorder improve dramatically with drugs based on the amino acid L-dopa, such as carbidopa-levodopa (Sinemet), which the body converts into dopamine.

Other medications
Medications that promote or inhibit the functions of various molecules involved in nerve signaling may have a moderate treatment effect. Common medications include:

• Anticholinergics (Cogentin, trihexyphenidyl)
• Benzodiazepines (Valium, Klonopin)
• Baclofen (Lioresal)

Botulinum toxin
Botulinum toxin type A (Botox) and botulinum toxin type B (Myobloc) are derived from the Clostridium botulinum bacterium. Botulinum toxins block the release of a chemical messenger that triggers muscle contractions. When your doctor injects the toxin into a muscle, it causes local muscle weakness. For many people, especially those with a focal dystonia, these treatments may significantly reduce or eliminate contractions. The effect wears off and injections need to be repeated approximately every three months.

Surgery
If people don't respond well to medication or botulinum toxin treatment, surgical procedures may be considered with certain types of dystonia. Surgical options include severing selected nerves for dystonia of the neck. However, most other types of dystonia cannot be treated this way.

A technique called deep brain stimulation involves implanting an electrode in the brain connected to a stimulating device in the chest that generates an electrical pulse. Activation of the electrode temporarily disables nerve activities. Occasionally, this is used in the treatment of severe dystonias with mixed success. In order to modulate the effect of the treatment, your doctor can adjust the frequency and intensity of electrical pulses.

Other treatments
A common phenomenon associated with dystonia is called a sensory trick, or "geste antagoniste." Touching an affected or adjacent body part can sometimes significantly reduce contractions. For example, placing a hand on the chin, side of the face or back of the head may reduce neck muscle contractions. People with dystonia typically discover this and use this trick to reduce their own dystonic contractions. Some physical therapists have developed head or neck braces, hand splints or other devices that mimic the sensory trick.

A physical therapist may also recommend stretches and exercises that enhance your flexibility and range of motion, strengthen underutilized muscles and promote optimal posture. The therapist may identify movements or activities that exacerbate dystonia symptoms and help you develop methods to avoid those movements or to substitute them with movements that result in better motor control.

A speech-language pathologist may help you alleviate difficulties with speaking, eating or swallowing.

Psychotherapy may be beneficial in managing stress, depression or anxiety associated with dystonia.