The first description of dystonia specifically responsive to levodopa was provided in 1971 by Segawa (Segawa et al 1971). In the midst of the excitement of Parkinson disease treatment with levodopa, Segawa reported several young girls with prominent diurnal variation of dystonia whose symptoms were ameliorated with low-dose levodopa (Segawa et al 1976). Subsequent reports described families whose members had dystonia and parkinsonism that improved markedly following levodopa treatment. Further studies have distinguished dopa-responsive dystonia from young-onset Parkinson disease with dystonia and have clarified the genetic basis of the disorder. Among the inherited forms of secondary dystonia, dopa-responsive dystonia or hereditary progressive dystonia with diurnal variation (HPD) is classified as DYT5, a “dystonia-plus syndrome,” because of its association with other neurologic features (ie, parkinsonism), although evidence of neurodegeneration is lacking (Fahn et al 1998).