Dystonia is defined as sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures. Classification of dystonia is based on three axes describing, for each patient, age at disease onset (early vs. adult), distribution of involved body sites (from focal to generalised), and aetiology (primary dystonia syndromes, heredodegenerative or symptomatic dystonias). Primary dystonias are further subdivided into primary pure (with dystonia only), primary plus (with other associated movement disorders) and primary paroxysmal forms (characterised by intermittent symptoms). Dystonia encompasses a combination of movements and postures to generate sustained muscle contractions, repetitive twisting movements and abnormal postures (torsion dystonia). In dystonic movements speed of contractions may be slow or rapid, but at the peak of movement it is sustained and movements have a consistent directional or posture-assuming character. Dystonia has some unique activation/deactivation features: gestes antagonistes (or sensory tricks), mirroring, and overflow. It has been shown that both genetic predisposition and environmental factors play a significant role in the aetiology of primary dystonia syndromes. Genetic defects are known only for a minority of cases presenting with pure dystonia (such as for DYT1 or DYT6 dystonias), by contrast, dystonia plus syndromes (dopa responsive dystonia, myoclonus dystonia and rapid onset dystonia parkinsonism) are caused by known genotypes. There is no aetiologic or neuroprotective treatment for primary pure dystonia syndromes. Etiologic remedies are instead available for some dystonia plus syndromes of metabolic origin, such as for dopa responsive dystonia. Symptomatic treatments aim to relieve involuntary movements, correct abnormal posture, prevent contractures, reduce pain and embarrassment, and improve function. Botulinum toxin is the first choice treatment for most types of focal dystonia. Neurosurgical treatments have a growing role in the symptomatic treatment plan, because long-term electrical stimulation of the globus pallidum internum is now established as an effective treatment for primary generalised or segmental dystonias.
|Titolo della pubblicazione ospite||Hyperkinetic movement disorders. Differential diagnosis and treatment|
|Editor||ALBERTO ALBANESE, Joseph Jankovic|
|Numero di pagine||20|
|Stato di pubblicazione||Pubblicato - 2012|