July 20, 2015: Dopamine-Responsive Dystonia
July 20, 2015
Dopamine-responsive dystonia or DRD is an inherited disorder presenting in childhood and characterized by a marked response to treatment with dopamine. Two main gene mutations account for the majority of DRD cases: the first is a point mutation on the gene for guanosine triphosphate cyclohydrolase I (GCH1) and the second is a direct mutation to the tyrosine hydroxylase gene itself.
Clinically, young patients present with a gait disturbance from dystonic posturing of one lower extremity which progresses to all four limbs. Patients in early disease worsen symptomatically over the course of the day due to nocturnal dopamine production during REM sleep. Other features include mild parkinsonism on exam without resting tremor or rigidity as well as equinus posturing. By definition, young DRD patients see a reversal of symptoms with administration of dopamine, and limb contractures occur in untreated patients. For this reason, the mainstay of treatment is with long-term low-dose levodopa-carbidopa.
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- Tadic V, Kasten M, Brüggemann N, Stiller S, Hagenah J, Klein C. Dopa-responsive dystonia revisited: diagnostic delay, residual signs, and nonmotor signs. Archives of Neurology 2012; 69: 1558-1562.
Submitted by Sarah Wesley MD, Department of Neurology, Mount Sinai Beth Israel Medical Center.
Disclosures: Dr. Wesley is a member of the Residents & Fellows Section of Neurology.