Definition and causes of Dystonia

Dystonia means wrong tension (dys = wrong tonus = tension) and is a state of sustained muscle contractions in certain muscle groups or repetitive, involuntary movements with painful spasms and fixed postures. It can lead to an abnormal body position and problems with walking or performing other voluntary movements.

The reason for the involuntary muscle movements is a disturbance in a deep area of the brain called the basal ganglia. This area controls the basic tension (rigidity) of the muscles and coordination of movements. A disturbance here leads to abnormal tension/rigidity in some muscles, and there may be problems controlling the movements of some muscle groups. 

 Around 1 in every 2.000 citizens in the western world has dystonia as the main diagnosis. Many of these are hereditary forms of involuntary muscle movements, but in part the cause is not known. In addition, there are many others who have involuntary muscle movements as part of other neurological diseases, for example Parkinson's disease, cerebral palsy or chorea. Moreover, a number of rare defects in metabolism and certain types of medication (for example Retrovirals for certain psychiatric disorders) result in involuntary muscle movements.

There are many different types of involuntary muscle movements. Overall, these are divided into generalized forms, involving the whole body, and localized forms which only involve individual muscles or muscle groups. Further division is described below.

Symptoms of Dystonia

Generalized involuntary muscle contractions/spasms:
Begin usually in child age and there will often be others in the family, who have had similar symptoms. It often starts with muscles in the feet and legs contracting in spasms pulling toes, the foot or the ankle into wrong position and it will therefore soon be difficult to walk. Within a few years dystonia spread to muscles in the rest of the body resulting in abnormal body positions. There will often be involuntary wringing movement, which prevents the person from walking or sitting upright. 

• Idiopathic generalized dystonia: Slowly progressing involuntary wringing movements of all 4 limbs or possibly the whole body. Begins typically around 5-15 years of age. It is often hereditary.
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• Dopa-responsive dystonia (Segawa): Rare hereditary disorder that begins around 3-4 years of age with involuntary muscle contractions in the legs, particularly when the patient is tired, later spreading to the rest of the body. A substance called L-dopa, can eliminate the symptoms if administered daily in small doses.

Localized involuntary muscle movements:
The symptoms of localized dystonia are limited to individual muscle groups. The most common forms of localized dystonia are torticollis (painful neck spasms), and scoliosis (abnormal curvature of the spine). Typically, symptoms begin in early adulthood. The symptoms depend on what muscle groups are involved. Many also have pain in the involuntarily contracting muscles, as well as in adjacent muscle groups and distorted body position as for example the neck. - There are the following types:

• Torticollis: Painful spasms and twitching in the neck muscles pulling the head to one side and possibly also leaning a little.
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• Blepharospasm: Involuntary contractions of the muscle around the eyes on both sides. Both eyes are squeezed together so hard that the patient might be unable to open the eyes voluntarily.
• Hemifaciale spasm: Involuntary contractions of facial muscles on one side only.
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• Cranial dystonia (Meiges syndrome or Bruegels disease): Usually begins at the age 30-70 years with blepharospasm and strange involuntary movements of the face, jaw, tongue, palate, throat, neck and breathing muscles. This leads to grimace and outbreaks of sounds.;
• Writing spasms (or profession convulsions): Some people, who are accustomed to writing, get sudden spasm of the fingers when trying to write. Spasms may also arise in connection with other activities as for example tooth brushing, use of tools or the like. The condition is often painful. The cause is unknown.
• Medicine induced dystonia: This comes in two forms: Acute occurring alongside the beginning of treatment with neuroleptics (used to treat psychiatric disorders) and after many years of treatment with neuroleptics (Tardive dystonia). Acute medicine induced dystonia occurs after days to weeks of therapy and shows as involuntary forced upward movement of the eyes or squint (cross eye). There may also be dramatic tension and stiffness in the neck and shoulder muscles and a tendency to poke the tongue out of the mouth. The tardive dystonia usually begins in the neck or facial muscles. Some cases fall into the category bucco-mastico-lingvalt syndrome (BML), which means repeated involuntary jaw, tongue and chewing movements. The condition might spread to the entire body if the treatment with neuroleptics is not stopped. 

Precautions and diagnosis of Dystonia 

If you are experiencing involuntary muscle movements you should consult your doctor, who might refer you to a neurologist for further examination.
 

The diagnosis is based on the historic symptom picture. Besides, it is possible to make a genetic study, where it is suspected that the reason for the involuntary muscle movements may be an inherited disease. It should also be excluded, whether here could be an underlying disease, such as. Parkinson's disease, cerebral palsy or chorea. 

Treatment of Dystonia

Generalized dystonia:
Treatment of generalized involuntary muscle spasms are often difficult, with disappointing results. Drugs inhibiting the conductivity in certain nerve cells (anticholinergics) and sedate like benzodiazepines might be tried. The hereditary dopa-responsive form, however, respond well to daily treatment with a low dose of L-dopa.

A new treatment has arrived over the past few years where thin electrodes are inserted directly into the basal ganglia part of the brain. These electrodes are connected to a small impulse device, which is inoperated under the skin on the chest supplying electrical impulses into the malfunctioning area of the brain. The faulty nerve impulses causing the spasms are thereby disrupted and the involuntary spasms stop.

Localized dystonia:
Botulinum is a potentially deadly toxin produced by the bacteria Clostridium botulinium. This toxin inhibits the transmission of nerve impulses to the muscles resulting in muscle paralysis. Botulism requires immediate treatment but when applied medically in tiny doses botulinium toxin acts as an effective muscle relaxant drug which is injected into the affected muscles, after which they relax. The effect persists for 10-16 weeks, after which there will be a new injection. Some become immune to the toxin, so it no longer has the same effect. The injection with botulinium toxin is a specialist job and the toxin is given in very small and carefully measured doses.

Some patients with torticollis can be treated surgically if the botulium toxin treatment is ineffective. The nerves controlling the neck muscles are severed paralyzing these muscles permanently. This surgical treatment is primarily used only for patients severely affected by involuntary muscle contractions.

Complications and outlook

Some patients find that the involuntary muscle contractions spontaneously improve or disappear. However, they may recur after some time. Involuntary muscle contractions that are triggered by neuroleptics may improve after discontinuation of medication. After many years of treatment with neuroleptics, however the risk that the involuntary muscle contractions are permanent is great.

In severe involuntary muscle contractions there is a risk of distortion of joint positions such as an abnormal curvature of the spine. Some patients become disabled by their symptoms as they may have difficulty controlling their movements, and some suffer severe pain in the muscles.Additionally, for many, the involuntary muscle contractions represent a major psychological stress, which can lead to a genuine depression.

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