Secondary dystonias

Secondary or symptomatic dystonias are (1) often accompanied by other neurological deficits. (2) begin suddenly at rest and occur at rest from the onset, (3) are associated with different hereditary and environmental causes. From an aetiological point of view, secondary dystonias can be caused by focal brain lesions of various origin, neurodegenerative disorders, metabolic disorders of the central nervous system (CNS), and several drugs and chemicals that affect the basal ganglia, thalamus and brain stem. Furthermore, secondary (focal) dystonias can be caused by peripheral injury. In the following review, we will discuss epidemiology, genetics, pathogenesis, neuroimaging, neuropathology, clinical manifestation, clinical course and differential diagnosis of secondary dystonias. Therapeutic options are given depending on the aetiology and the topological type of dystonia.