Generalised, multifocal or segmental idiopathic torsion dystonia (ITD), is caused by an autosomal dominant gene with reduced penetrance in about 85% of cases. Of 104 patients with these types of ITD, 17 (16.4%) gave a history which suggested that dystonic movements had been precipitated or exacerbated by trauma. Eight of these 17 patients had affected relatives. If precipitated, dystonia appeared first in the injured part of the body within days or up to 12 months after the trauma and later became more widespread. Peripheral injuries may influence basal ganglia function and provoke the onset of dystonic movements in individuals who are ITD gene carriers.