Kinematic aspects of the step movement in Parkinson's disease

In an attempt to understand the fundamental mechanism for movement disturbances in Parkinson's disease (PD) patients, we investigated their straightforward or right diagonally (laterally) steps and step over a stick. In all tasks, in PD patients, the movement latency was significantly longer and the movement duration was significantly shorter than those of the controls. In the lateral step task, the maximum velocity of PD subjects was significantly faster than that of the controls, while the reaching time to maximum velocity was longer. Moreover, in the task to step over a stick, the reaching time to maximum velocity was significantly longer than that of the controls. In the velocity profiles, in PD patients, the deceleration after the maximum acceleration was rapider than that of the controls. In addition, the PD patients' jerk was significantly larger than that of the controls. These results suggest that PD patients have deficits in motor programming and motor control which may be due to dysfunction of the cortico-basal ganglia loop.