Dr. Alfradique-Dunham of Baylor College of Medicine has no relevant financial relationships to disclose.)
Dr. Jankovic, Director of the Parkinson's Disease Center and Movement Disorders Clinic at Baylor College of Medicine, has received research and/or training grants from Adamas, Allergan, Biotie, Civitas/Acorda, Hoffmann-La Roche, Medtronic, Merz, Neurocrine , Nuvelution, Pfizer, Prothena, Psyadon, Revance, and Teva; and has served as a consultant or as an advisory committee member for Adamas, Allergan, Merz, Prothena, Revance, and Teva.)
This article includes discussion of isolated dystonia, primary dystonia, idiopathic torsion dystonia, and dystonia. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Dystonia is a movement disorder characterized by patterned, twisting movements of the body that can result in abnormal postures. Isolated dystonia refers to dystonia without other neurologic findings besides tremor. Isolated dystonia is often familial but can be sporadic, especially in adults. Besides an association with a genetic mutation, primary dystonia is not secondary to an underlying structural lesion, metabolic disturbance, or medication. There are various forms of primary dystonia that will be described in this article.
• Patients present with pure dystonia with the exception of tremor.
• Atypical features such as cognitive impairment, seizures, pyramidal signs, and retinal findings would suggest secondary causes.
• Genetic testing should be considered in younger patients or those with a family history.
• Treatment can include oral medications, botulinum toxin injections, and deep brain stimulation.
Historical note and terminology
The term "dystonia" was coined by Oppenheim in 1911 when he introduced the term “dystonia musculorum deformans” to describe 4 individuals in whom “muscle tone was hypotonic at one occasion and in tonic muscle spasm at another, usually, but not exclusively, elicited upon voluntary movements” (Oppenheim 1911). He stressed that there was no loss of muscle power, change in sensation, or psychological illness. For a large part of the 20th century, dystonia was considered psychogenic by many, until the 1970s when many characteristics of idiopathic torsion dystonia were further described (Marsden and Harrison 1974). In 1984, the Dystonia Medical Research Foundation provided the first consensus definition of dystonia consisting of “sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures” (Fahn et al 1987). An international panel of dystonia experts proposed a revised definition: “dystonia is a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. Dystonic movements are typically patterned, twisting, and may be tremulous. Dystonia is often initiated or worsened by voluntary action and associated with overflow muscle activation” (Albanese et al 2013).
The nomenclature used to describe dystonia has evolved over time, with dystonia musculorum deformans being replaced by idiopathic torsion dystonia and then primary dystonia (Bressman and Saunders-Pullman 2013). Dystonia has classically been categorized along 3 axes: age at onset, body distribution, and etiology. The international panel proposed classifying dystonia in 2 categories: clinical characteristics and etiology (Albanese et al 2013). The clinical characteristics axis includes age of onset, body distribution, temporal pattern, and associated features whereas the etiology axis comprises inherited, acquired, idiopathic causes or those due to a nervous system pathology. According to that classification, the term “primary dystonia” should not be used. It does not allow the axis classification as it has a dual meaning, referring to dystonias without other neurologic manifestations, which is a clinical characteristic, with genetic or idiopathic etiology. A preferred term is “isolated dystonia,” which encompasses dystonias without other associated movement disorders without establishing a specific etiology.
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