Impact of subthalamic stimulation and medication on proximal and distal bradykinesia in Parkinson's disease

OBJECTIVE: To evaluate the usefulness of a new instrument for bedside testing of proximal arm and distal finger tapping performance in patients with Parkinson's disease (PD).

METHODS: Twenty healthy controls and 25 PD patients with subthalamic nucleus deep brain stimulation were investigated in different treatment conditions using three different tapping paradigms: (1) the standard tapping task of the CAPSIT-PD-protocol; (2) alternate pressing of two buttons on the new board by moving the arm at the elbow and shoulder (proximal tapping), and (3) alternate pressing of two closely collocated buttons on the new board by moving only the index finger (distal tapping) for 30 s.

RESULTS: The new tapping board was as sensitive as the standard board to distinguish untreated PD patients from controls. The relative improvements in tapping scores from the off treatment condition were largest for the proximal tapping task. The treatment effects of high frequency stimulation of the subthalamic nucleus or medication alone were comparable, whereas the combined treatment induced significantly higher tapping scores.

CONCLUSION: The new tapping board represents a quick and easy to use bedside test, which may be routinely used to probe the efficacy of treatments on different aspects of motor control.