Perception of Active and Passive Turning in Parkinson Disease

Background. Many individuals with Parkinson disease (PD) experience difficulty with turning, yet little is known about the reasons for this difficulty.Objective. The authors sought to determine whether individuals with PD can use visual, vestibular, and proprioceptive cues to estimate how far they have turned.Methods. Fifteen PD subjects and 11 controls performed active and passive turns to the left and right, with and without vision, with amplitudes of 90, 180, 270, and 360 degrees. For active conditions, subjects were told the direction and amplitude of the desired turn and then attempted to turn in place the specified amount via actively stepping. For passive conditions, subjects were told that the disc they stood on would turn and they were to press a button when they had traveled the specified amplitude.Results. There were no differences between PD and control groups in any of the conditions, suggesting that those with PD effectively used sensory cues available in the different conditions to accurate...