Objective: The aim of this review is to investigate whether or not the current classification systems of dystonia is appropriate, and if not to present suitable alternatives. Additional goals are to investigate if and how the different sub groups of dystonia can be separated clinically, when to suspect a genetic cause and identify when further investigations are indicated. Finally we want to illuminate the importance and the possibilities achieved by understanding the genetic background of the disease.
Background: Dystonia is a rare syndrome characterised by involuntary muscle contractions, producing twisting and repetitive movements in a predictable pattern, or abnormal postures. In many cases an underlying genetic cause is identified. Dystonia is commonly classified by age of onset, distribution of symptoms and aetiology.
Method: Literature searches in McMaster Plus, PubMed, Ovid, Cochrane, Google Scholar and Medline performed mainly in the period between January 2012 and August 2012. Only articles written in English and Norwegian are included. Searches were based on relevant key words concentrating on the correlation between dystonia and genetics. A total of 40 articles were reviewed.
Result and Conclusion: Are the current classification systems appropriate?The classification by age into early onset (< 26 years) and late onset (> 26 years) dystonia is appropriate from a clinical point of view. The categorisation by means of distribution into focal, segmental and generalized dystonia is also useful for the clinician. The genetic classification, i.e. various types of DYTs, should be reserved for specialists in genetics.
Is it possible to separate the different sub groups of dystonia clinically?In many cases of dystonia, an investigation based on age of onset, symptoms and the development of the disease is sufficient for the diagnosis. Genetic testing is sometimes necessary in finding an exact diagnosis, but should be reserved for specialists in genetics. Specific guidance for various clinical situations is presented in the article.
Importance of a genetic diagnosisAn understanding of genetics is crucial to drive the field forward. Specialized centers should be responsible for this.