Paroxysmal exercise-induced dystonia as a presenting feature of young-onset Parkinson's disease.

Paroxysmal exercise-induced dystonia (PED) is a rare, typically idiopathic familial condition, although sporadic and secondary cases have been reported. We present 2 cases where PED was the presenting feature of young-onset idiopathic Parkinson's disease (PD), preceding the onset of parkinsonian symptoms by 1.5 and 5 years, respectively. Initially, the dystonic symptoms occurred after prolonged exercise and were unilateral, affecting the foot in both patients. Over time, symptoms occurred with minimal exercise. We conclude that PED can rarely be the first and only feature of PD.