title: Temporal organization of stride duration variability as a marker of gait instability in Parkinson's disease.
abstract: OBJECTIVE
  Gait instability and fall risk are major concerns in Parkinson's disease. This study shows that the temporal organization of gait variability can represent a marker of gait instability that complements standard assessment of motor deficits in Parkinson's disease.
  
  
  METHODS
  Temporal organization (long-range autocorrelation; LRA) of stride duration variability, collected from 20 persons with Parkinson's disease walking overground at a comfortable speed, was studied. The presence of LRA was based on the scaling properties of the series variability and the shape of the power spectral density. Simultaneously, measures of neurological impairment (MDS-UPDRS), balance (BESTest), and balance confidence (ABC-Scale) were collected. To precisely identify the relationship between LRA and functional measures, correlation coefficients were applied.
  
  
  RESULTS
  Degradation of LRA was strongly correlated with other clinical scores, in such a way that the temporal organization of gait variability was more random for patients presenting with greater motor impairments. Importantly, these measures were relatively independent of age, and gait speed, thus they can be applied to a wide clinical population.  Conclusion: The findings of this study emphasize that temporal organization of gait variability is related to degree of functional impairment in Parkinson's disease. LRA may thus be regarded as an objective and quantitative measure of gait stability for both clinical practice and research.
authors.affiliation: Physical and Rehabilitation Medicine Department, Cliniques universitaires Saint-Luc, 1200 Brussels, Belgium.
authors.forename: Thibault
authors.initials: T
authors.lastname: Warlop
authors.forename: Christine
authors.initials: C
authors.lastname: Detrembleur
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bollens
authors.forename: Gaëtan
authors.initials: G
authors.lastname: Stoquart
authors.forename: Frédéric
authors.initials: F
authors.lastname: Crevecoeur
authors.forename: Anne
authors.initials: A
authors.lastname: Jeanjean
authors.forename: Thierry M
authors.initials: TM
authors.lastname: Lejeune
mesh_terms: D000054:Acceleration; D061725:Accelerometry / Q000379:methods; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D004856:Postural Balance; D012720:Severity of Illness Index; D013997:Time Factors; D016138:Walking / Q000502:physiology