The dystonias are movement disorders in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The involuntary and sometimes painful movements may affect a single muscle, a group of muscles such as those in the arms, legs, or neck, or the entire body.
Birth injury (particularly due to lack of oxygen), certain infections, reactions to certain medication, heavy metal or carbon monoxide poisoning, trauma or stroke can cause dystonic symptoms.
About half the cases of dystonia have no connection to disease or injury and are called primary or idiopathic dystonia. Of the primary dystonias, many cases appear to be inherited.
Early symptoms may include deterioration in handwriting after writing several lines, foot cramps, and a tendency of one foot to pull up or drag after running or walking some distance. Other possible symptoms are voice or speech difficulties, and tremor.
Dystonias can also be symptoms of other diseases, some of which may be hereditary. In some individuals symptoms of a dystonia appear in children between the ages of five and sixteen, usually in the foot or in the hand. For other individuals, the symptoms emerge in late adolescence or early adulthood.
The initial symptoms can be very mild and may be noticeable only after prolonged exertion, stress or fatigue. Over a period of time, the symptoms may become more noticeable and widespread and be unrelenting. Sometimes there is, however, little or no progression.
No one treatment has been found universally effective. Instead, doctors use a variety of therapies (medication, surgery and other treatments such as physical therapy, splinting, stress management and biofeedback) aimed at reducing or eliminating muscle spasms and pain. Since response to medication varies among patients and even in the same person over time, the most effective therapy is often individualised.
Reviewed by Dr Andrew Rose-Innes, Department of Neurology, Yale University School of Medicine, 2007