Parkinson's disease and segmental coordination during turning: II. Walking turns.

OBJECTIVE Individuals with Parkinson's disease (PD) show poorer balance and greater incidence of falls while turning. We investigated whether a disturbance in timing and sequence of reorientation of body segments is a potential cause of turning difficulty in PD and is altered by levodopa. METHODS The sequence and timing of segmental reorientation during 45° and 90° walking turns were recorded in nineteen healthy controls and fourteen individuals with PD "off" and "on" medication. RESULTS Both healthy elderly and PD patients "off" medication displayed a top-down sequence of segment reorientation, but differed with respect to the delay time between segments: PD "off" medication displayed a shorter delay between the onset of head and shoulder reorientation and longer delays for pelvis and foot reorientation. Furthermore, for all segments the peak angular velocities were lower for PD patients than healthy controls, with greater difference between the two groups during larger turns. While for both groups the velocity and magnitude of rotation of all segments were greater during larger turns, the relative timing of reorientation of segments remained the same during small and large turns. Medication had no significant effect on the timing and sequence of reorientation of segments and caused only a small and non-significant increase to segment velocities. CONCLUSION This study further characterized the turning performance of individuals with PD. Our findings have clinical applications and therapeutic value for PD patients with difficulty turning. Understanding the specific deficiencies of turning performance of PD patients allows the therapists to opt for the most effective rehabilitation techniques.