Compulsive singing: another aspect of punding in Parkinson's disease.

We report on two patients with advanced Parkinson's disease who were exhibiting a peculiar and stereotyped behavior characterized by an irrepressible need to sing compulsively when under high-dose dopamine replacement therapy. Sharing many features with punding, this singing behavior is proposed as a distinct manifestation of the dopamine dysregulation syndrome in Parkinson's disease.