Dystonia is a neurological movement disorder characterized by involuntary muscle contractions, which force certain parts of the body into abnormal, sometimes painful, movements or postures. Dystonia can affect any part of the body including the arms and legs, trunk, neck, eyelids, face, or vocal cords.
If dystonia causes any type of impairment, it is because muscle contractions interfere with normal function. Features such as cognition, strength, and the senses, including vision and hearing are normal. While dystonia is not fatal, it is a chronic disorder and prognosis is difficult to predict.
It is the third most common movement disorder after Parkinson’s disease and Tremor, affecting more than 300,000 people in North America. Dystonia does not discriminate – affecting all races and ethnic groups.
Brief History of Dystonia
Dystonia, like many other chronic neurological disorders, was recognized as a distinct entity only relatively recently. Even before the term “dystonia” was coined, people with the syndrome were being reported explicitly in the literature.
In 1911, Hermann Oppenheim, an esteemed Berlin neurologist who wrote a leading textbook of neurology, was impressed with the variation in muscle tone seen in a neurologic syndrome that he had encountered in several young boys. He coined the term “dystonia” to indicate that “muscle tone was hypotonic at one occasion and in tonic muscle spasm at another, usually, but exclusively, elicited upon volitional movements.” The term was widely accepted and has been used by neurologists ever since, even though throughout time, the definition changes. In addition to alteration of muscle tone, Oppenheim also described twisted postures associated with the muscle spasms affecting limbs and trunk, bizarre walking with bending and twisting of the torso, rapid and sometimes rhythmic jerking movements, and progression of symptoms leading eventually to sustained fixed postural deformities.
In 1944, Ernst Herz, from analysis of cinematographic and eletromyographic recordings, regarded slow sustained postures as the best definition for dystonia.
In 1962, Derek Denny-Brown expanded upon this definition and defined dystonia as a fixed or relatively fixed attitude. One problem with using only sustained postures for the definition of dystonia is that it allows all types of abnormal postures to be called dystonia, such as fixed postures that could develop from a stroke. Another problem is that these definitions do not take into account the other types of abnormal movements seen in the disorder.
In February, 1984, a committee consisting of members of the Scientific Advisory Board of the Dystonia Medical Research Foundation met, deliberated, and developed the following definition: “dystonia is a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures.” The committee consisted of Drs. AndrÈ Barbeau, Donald B. Calne, Stanley Fahn, C. David Marsden, John H. Menkes, and G. Fred Wooten. This definition is still utilized.
This committee also proposed a classification scheme for all types of dystonia, recommending that there should be three classification schemes: by age at onset, by parts of body affected, and by etiology. With the advent of discovering different genetic types of dystonia, the etiologic classification was changed at the time of the 3rd International Dystonia Symposium in 1996. The main definition of dystonia will most likely remain the same, but the etiologic classification will change over time as new genetic forms are described.
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