title: Overestimation of stability limits leads to a high frequency of falls in patients with Parkinson's disease.
abstract: OBJECTIVE
  To test a hypothesis that patients with Parkinson's disease may not notice discrepancies between their perceived and actual stability limits and cannot keep their centre of gravity within the stability region.
  
  
  METHODS
  Outpatients with neurological disorders in rehabilitation service.
  
  
  METHODS
  Twenty-one patients with Parkinson's disease (11 men, 10 women; mean duration 5.9 +/- 3.9 years) and age- and sex-matched healthy volunteers were recruited.
  
  
  METHODS
  Each subject's right arm length was subtracted from the distance between the right acromion and the perceived reachable boundary. This was called 'perceived reach'. The figure given by subtracting the right arm length from the maximum forward reach length measured by the Functional Reach Test was named 'actual reach', and is an index of actual stability limits in each subject. The difference between actual and perceived stability limits (DAP) is given by actual reach minus perceived reach. The motor score of the Unified Parkinson's Disease Rating Scale were used to evaluate disease severity.
  
  
  RESULTS
  The mean DAP for the Parkinson's disease group was negative (-1.8 +/- 5.7 cm) and significantly different from that of controls (3.3 +/- 9.2 cm) (P < 0.05). In Parkinson's disease, DAP was significantly correlated with the Unified Parkinson's Disease Rating Scale score (correlation coefficient = -0.39, P < 0.05).
  
  
  CONCLUSIONS
  These results indicated that patients with Parkinson's disease overestimated their stability limits, which may result in falls. In addition, the results demonstrate that patients with Parkinson's disease develop overestimation of stability limits in parallel with their disease progression.
authors.affiliation: Rehabilitation Unit, Osaka University Hospital, Suita, Osaka, Japan. nkamata@hp-rehab.med.osaka-u.ac.jp
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kamata
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yoneda
authors.forename: Hideki
authors.initials: H
authors.lastname: Shinohara
authors.forename: Satoru
authors.initials: S
authors.lastname: Inoue
authors.forename: Kazuo
authors.initials: K
authors.lastname: Abe
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000368:Aged; D016022:Case-Control Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D010300:Parkinson Disease / Q000503:physiopathology*; D011434:Proprioception / Q000502:physiology*; D012307:Risk Factors; D012720:Severity of Illness Index