title: Perception of active and passive turning in Parkinson disease.
abstract: 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 accurately judge distance turned. The authors found no apparent deficits in the visual, vestibular, or proprioceptive systems or in integration of these senses for performance of the turning task tested.
  
  
  CONCLUSIONS
  Turning difficulties associated with PD may more likely relate to motor or sensorimotor integration deficits than to pure sensory or sensory integration deficits. Generalizability of the study may be limited by the fact that subjects were tested at a single velocity for passive rotations, were on medication, and had relatively mild PD (primarily H&Y 2).
authors.affiliation: Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO 63108, USA. earhartg@wustl.edu
authors.forename: Gammon M
authors.initials: GM
authors.lastname: Earhart
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Stevens
authors.forename: Joel S
authors.initials: JS
authors.lastname: Perlmutter
authors.forename: Minna
authors.initials: M
authors.lastname: Hong
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010300:Parkinson Disease / Q000503:physiopathology* / Q000534:rehabilitation; D010465:Perception / Q000502:physiology*; D011434:Proprioception / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D012399:Rotation; D014722:Vestibule, Labyrinth / Q000502:physiology