[Dystonia: their epidemiology, aetiology, diagnosis and treatment]

Dystonia is the second most common movement disorder after Parkinsonism. No exact figures are available on the incidence/prevalence of the different forms of dystonia, because the data vary considerably depending on the source, method and ethnic origin of the population under study.

To describe and summarise our current knowledge of the epidemiology, causation, diagnosis and treatment of dystonias.

Dystonia is a movement disorder characterised by sustained muscular contractions that cause repeated twisting movements and abnormal postures. Dystonias can be classified according to their distribution, aetiology, clinical course and age at onset. A correct classification is very useful for evaluating the complementary tests that are needed, as well as the prognosis and treatment of the process. The diagnosis of dystonia is essentially clinical and is confirmed with electromyography. Both the different laboratory and neuroimaging studies are fundamentally used to help in the aetiological classification and to rule out secondary causes of dystonia. Among the different treatments that exist today (intrathecal, infiltrative, surgical, systemic pharmacotherapy), special attention should be given to the role of botulinum toxin as the preferred treatment in most cases of focal dystonias.

Exhaustive epidemiological studies are needed to be able to get a more precise picture of the epidemiology of dystonias. Despite the great amount of progress made in recent years as far as genetics and neuroimaging are concerned, the diagnosis of dystonia remains essentially clinical. Botulinum toxin is the preferred treatment in most cases of focal dystonias.