Clinical effect of stimulation of different targets. (A) Schematic representation of the STN and SNr in the sagittal plane (adapted from Morel et al., 2007). Monopolar stimulation of the STN resulted in aggravation of myoclonia, dyskinesia, dizziness, and worsening of gait. In the STN/SNr border zone, we observed mild Parkinsonism with slight beneficial effects on the myoclonus. Selective stimulation of the SNr resulted in reversible mild tremor and rigor, but low-amplitude stimulation was effective in suppression of myoclonus and resulted in significant amelioration of gait dysfunction. (B) Circle drawings by the patient upon monopolar stimulation of the subthalamic nucleus (STN), the borderzone (SNr/STN), and the substantia nigra (SNr). Action myoclonus was significantly reduced upon selective stimulation of the substantia nigra.