Diagnosis and pathogenesis of dystonia: clinical heterogeneity, shared mechanisms, and neurodevelopmental origins.

The diagnosis of dystonia is often delayed because of its many different clinical manifestations and causes. Updates to the definition and classification of dystonia can assist clinicians in improving its recognition and timely diagnosis. Dystonia is characterised by sustained or intermittent abnormal movements, postures, or both. Patterned phenomenology, alleviating manoeuvres, worsening by voluntary movement, and overflow to adjacent muscles are all clinical clues of the condition. Additional non-motor manifestations are part of the clinical spectrum. In parallel to the broad heterogeneity of clinical manifestations among different types of dystonia, the biological mechanisms underlying the condition are also heterogeneous. Among these mechanisms, an alteration of the sensorimotor circuits during crucial windows of development might have a role in many forms of dystonia. Advances in the understanding of its pathogenesis indicate that targeting shared mechanisms could provide a treatment approach for multiple types of dystonia, but also suggest the possibility of personalised therapeutic approaches.