title: Excessive postural sway and the risk of falls at different stages of Parkinson's disease.
abstract: Excessive postural sway may result in falls in Parkinson's disease (PD). We measured postural sway using the sensory organization test (SOT) of dynamic posturography in static (platform still) and dynamic (sway referenced platform) conditions with normal, no and inappropriate visual feedback in 102 subjects with PD, off medication. Twenty-five healthy subjects were used as age-matched controls. Eighteen very early stage PD subjects had never used dopaminergic medication. Postural sway was normal in those subjects in all conditions, but was abnormal in subjects with more advanced symptoms (UPDRS III > 20, P < 0.01). Postural sway increased with disease severity in all conditions except static, eyes closed (P < 0.0001). We developed the SOT Fall Severity Scale (SOTFSS) from the number of times postural sway was so large that the subject had to take a step (registered as a "fall") and showed that falls mainly occurred in dynamic conditions, and were correlated with disease severity (P < 0.0001). In dynamic conditions the SOTFSS was correlated with the retropulsion score from the UPDRS III (N = 102, P < 0.0001) and with the subjects' self-reported fall frequency from the UPDRS II (N = 62, SOT5: P = 0.0419, SOT6: P = 0.0034).
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford University, Stanford, California 94305-5327, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Frenklach
authors.forename: Stephanie
authors.initials: S
authors.lastname: Louie
authors.forename: Mandy Miller
authors.initials: MM
authors.lastname: Koop
authors.forename: Helen
authors.initials: H
authors.lastname: Bronte-Stewart
mesh_terms: D000058:Accidental Falls / Q000706:statistics & numerical data*; D005246:Feedback; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology* / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D015995:Prevalence; D012307:Risk Factors; D012678:Sensation Disorders / Q000175:diagnosis / Q000453:epidemiology; D012720:Severity of Illness Index