title: Light and heavy touch reduces postural sway and modifies axial tone in Parkinson's disease.
abstract: BACKGROUND
  Light touch with a stable object reduces postural sway by increasing axial postural tone in healthy subjects. However, it is unknown whether subjects with Parkinson's disease (PD), who have more postural sway and higher axial postural tone than healthy subjects, can benefit from haptic touch.
  
  
  OBJECTIVE
  To investigate the effect of light and heavy touch on postural stability and hip tone in subjects with PD.
  
  
  METHODS
  Fourteen subjects with mid-stage PD and 14 healthy control subjects were evaluated during quiet standing with eyes closed with their arms (a) crossed, (b) lightly touching a fixed rigid bar in front of them, and (c) firmly gripping the bar. Postural sway was measured with a forceplate, and axial hip tone was quantified using a unique device that measures the resistance of the hips to yaw rotation while maintaining active stance.
  
  
  RESULTS
  Subjects with PD significantly decreased their postural sway with light or heavy touch (P < .001 vs arms crossed), similarly as control subjects. Without touch, hip tone was larger in PD subjects. With touch, however, tone values were similar in both groups. This change in hip tone with touch was highly correlated with the initial amount of tone (PD, r = -.72 to -.95; controls, r = -.74 to -.85).
  
  
  CONCLUSIONS
  The authors showed, for the first time, that subjects with PD benefit from touch similarly to control subjects and that despite higher axial postural tone, PD subjects are able to modulate their tone with touch. Future studies should investigate the complex relationship between touch and postural tone.
authors.affiliation: Oregon Health & Science University, Portland, OR, USA. erika.franzen@ki.se
authors.forename: Erika
authors.initials: E
authors.lastname: Franzén
authors.forename: Caroline
authors.initials: C
authors.lastname: Paquette
authors.forename: Victor
authors.initials: V
authors.lastname: Gurfinkel
authors.forename: Fay
authors.initials: F
authors.lastname: Horak
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000704:Analysis of Variance; D015259:Dopamine Agents / Q000627:therapeutic use; D018737:Hand Strength / Q000502:physiology; D006615:Hip / Q000503:physiopathology; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy; D026741:Physical Therapy Modalities; D004856:Postural Balance / Q000187:drug effects / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011312:Pressure; D012678:Sensation Disorders / Q000209:etiology* / Q000534:rehabilitation*; D012720:Severity of Illness Index; D019415:Torque; D014110:Touch / Q000187:drug effects / Q000502:physiology*
chemical_list: D015259:Dopamine Agents; D007980:Levodopa