Dystonia is a general term for a large group of movement disorders that vary in their symptoms, causes, progression, and treatments. This group of neurological conditions is generally characterized by involuntary muscle contractions that force the body into abnormal, sometimes painful, movements and positions (postures). The muscular contractions may be sustained or come and go (intermittent). Movements may be patterned and twisting, and/or in some cases shaking or quivering (tremulous) resembling a tremor. Dystonia may occur or be worsened when an individual attempts a voluntary action. Dystonia can affect one muscle, a muscle group, or the entire body. Dystonia affects about 1% of the population, and women are more prone to it than men.
Dystonia results from abnormal functioning of the basal ganglia, a deep part of the brain which helps control coordination of movement. These regions of the brain control the speed and fluidity of movement and prevent unwanted movements. Patients with dystonia may experience uncontrollable twisting, repetitive movements or abnormal postures and positions. These can affect any part of the body, including the arms, legs, trunk, face and vocal cords.
Dystonia can affect many different parts of the body and the symptoms are different depending upon the form of dystonia. Symptoms may include:
· a foot cramp or a tendency for one foot to turn or drag—either sporadically or after running or walking some distance
· a worsening in handwriting after writing several lines
· the neck may turn or pull involuntarily, especially when the person is tired or under stress
· both eyes might blink rapidly and uncontrollably; other times, spasms will cause the eyes to close
· difficulty speaking
The initial symptoms can be very mild and may be noticeable only after prolonged exertion, stress, or fatigue. Over time, the symptoms may become more noticeable or widespread; sometimes, however, there is little or no progression.
In some cases, dystonia can affect only one specific action, while allowing others to occur unimpeded. For example, a musician may have dystonia when using a hand to play an instrument, but not when using the same hand to type.
Dystonia may cause pain due to muscle contractions but typically is not associated with problems thinking or understanding. Depression and anxiety may occur.
Types of Dystonia
Dystonias are classified by the body part they affect:
Dystonias can also be classified as syndromes based on their patterns:
· Task-specific dystonias tend to occur only when undertaking a particular repetitive activity. Examples include writer's cramp that affects the muscles of the hand and sometimes the forearm, and only occurs during handwriting. Similar focal dystonias have also been called typist's cramp, pianist's cramp, and musician's cramp. Musician’s dystonia is a term used to classify focal dystonias affecting musicians, specifically their ability to play an instrument or to perform. It can involve the hand in keyboard or string players, the mouth and lips in wind players, or the voice in singers.
Most cases of dystonia do not have a specific cause. Dystonia seems to be related to a problem in the basal ganglia. That's the area of the brain that is responsible for initiating muscle contractions. The problem involves the way the nerve cells communicate.
Acquired dystonia is caused by damage to the basal ganglia. The damage could be the result of:
Idiopathic or primary dystonia is often inherited from a parent. Some carriers of the disorder may never develop a dystonia themselves. And the symptoms may vary widely among members of the same family.