Turning in Parkinson's disease patients and controls: the effect of auditory cues.

Turning is an impaired activity in persons with Parkinson's disease (PwPD). The current study examines the turning characteristics in PwPD (9 freezers and 10 nonfreezers) and 9 controls, and explores the effect of rhythmic auditory cues while turning. Turning parameters were collected from a 180 degrees left U-turn during a noncued and a cued condition, using a 3D measuring system. Auditory cues were supplied with a metronome at a rhythm equaling the subject's comfortable step frequency during straight line walking. Results showed that in contrast to controls, PwPD used a wider turning-arc and took smaller, narrower steps. In addition, they demonstrated a higher Coefficient of Variation (CV) of step duration (6.92%) compared to controls (4.88%, P < 0.05). The "wide-arc" turning strategy of PwPD was more prominent in freezers than in nonfreezers. Auditory cues reduced the CV of step duration in PwPD (both freezers and nonfreezers) during turning (from 6.92 to 6.00%, P < 0.05). In summary: Cueing reduced the gait-timing variability during turning, but PwPD maintained a wider arc to turn compared with controls.