ISway: a sensitive, valid and reliable measure of postural control (original) (raw)
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Assessment of postural control in patients with Parkinson’s disease: Sway ratio analysis
Human Movement Science, 2011
Analysis of the postural stability impairments in neurodegenerative diseases is a very demanding task. Age-related declines in posturographic indices are usually superimposed on effects associated with the pathology and its treatment. We present the results of a novel postural sway ratio (SR) analysis in patients with Parkinson's disease (PD) and age-matched healthy subjects. The sway ratios have been assessed based upon center of foot-pressure (CP) signals recorded in 55 parkinsonians (Hoehn and Yahr: 1-3) and 55 age-matched healthy volunteers while standing quiet with eyes open (EO) and then with eyes closed (EC). Complementing classical sway measure abnormalities, the SR exhibited a high discriminative power for all controlled factors: pathology, vision, and direction of sway. Both the anteroposterior (AP) and mediolateral (ML) sway ratios were significantly increased in PD patients when compared to the control group. An additional SR increase was observed in the response to eyes closure. The sway ratio changes documented here can be attributed to a progressive decline of a postural stability control due to pathology. In fact, a significant correlation between the mediolateral SR under EO conditions and Motor Exam (section III) score of the UPDRS was found. The mediolateral sway ratios computed for EO and EC conditions significantly correlated with the CP path length (r = .87) and the mean anteroposterior CP position within the base of support (r = .38). Both indices reflect postural stability decline and fall tendency # in parkinsonians. The tremor-type PD patients (N = 34) showed more pronounced relationships between the mediolateral SR and selected items from the UPDRS scale, including: falls (Kendall Tau = .47, p < .05), rigidity (.45, p < .05), postural stability (retropul-0167-9457/$ -see front matter Ó journal hom ep ag e: www.elsevier.com/loc ate/humov sion) (.52), and the Motor Exam score (.73). The anteroposterior SR correlated only with tremor (Kendal Tau = .77, p < .05). It seems that in force plate posturography the SR can be recommended as a single reliable measure that allows for a better quantitative assessment of postural stability impairments.
Journal of Neurology, Neurosurgery & Psychiatry, 2005
Objectives: Clinicians often base the implementation of therapies on the presence of postural instability in subjects with Parkinson's disease (PD). These decisions are frequently based on the pull test from the Unified Parkinson's Disease Rating Scale (UPDRS). We sought to determine whether combining the pull test, the one-leg stance test, the functional reach test, and UPDRS items 27-29 (arise from chair, posture, and gait) predicts balance confidence and falling better than any test alone. Methods: The study included 67 subjects with PD. Subjects performed the one-leg stance test, the functional reach test, and the UPDRS motor exam. Subjects also responded to the Activities-specific Balance Confidence (ABC) scale and reported how many times they fell during the previous year. Regression models determined the combination of tests that optimally predicted mean ABC scores or categorised fall frequency. Results: When all tests were included in a stepwise linear regression, only gait (UPDRS item 29), the pull test (UPDRS item 30), and the one-leg stance test, in combination, represented significant predictor variables for mean ABC scores (r 2 = 0.51). A multinomial logistic regression model including the one-leg stance test and gait represented the model with the fewest significant predictor variables that correctly identified the most subjects as fallers or non-fallers (85% of subjects were correctly identified). Conclusions: Multiple balance tests (including the one-leg stance test, and the gait and pull test items of the UPDRS) that assess different types of postural stress provide an optimal assessment of postural stability in subjects with PD.
Postural sway as a marker of progression in Parkinson's disease: a pilot longitudinal study
Gait & posture, 2012
Objective measures of postural control that are sensitive to Parkinson's disease (PD) progression would improve patient care and accelerate clinical trials. Although measures of postural sway during quiet stance in untreated PD have been shown to differ from age-matched control subjects, it is not known if sway measures change with disease progression in early PD. In this pilot study, we asked whether accelerometer-based metrics of sway could provide a practical tool for monitoring progression of postural dyscontrol in people with untreated or newly treated PD.We examined 13 subjects with PD and 12 healthy, age-matched control subjects. The PD subjects had been recently diagnosed and had not started any antiparkinsonian medications at the baseline session. All subjects were tested 3–6 months and 12 months after the baseline session. Subjects were asked to stand quietly for two minutes while wearing an inertial sensor on their posterior trunk that measured trunk linear acceleration.Our results suggested that objective sway measures deteriorated over one year despite minimal changes in UPDRS motor scores. Medio-lateral (ML) sway measures were more sensitive than antero-posterior sway measures in detecting progression. The ML JERK was larger in the PD group than the control group across all three testing sessions. The ML sway dispersion and ML sway velocity were also significantly higher in PD compared to control subjects by the 12-month evaluation. It is feasible to measure progression of PD prior to onset of treatment using accelerometer-based measures of quiet standing.► Objective sway measures deteriorated over one year. ► UPDRS motor scores did not show significant changes over one year. ► Medio-lateral (ML) sway measures were more sensitive than antero-posterior sway measures in detecting progression.
Journal of neurologic physical therapy : JNPT, 2008
Parkinson's disease (PD) predisposes one to falls, which in turn may lead to serious injury and decreased quality of life. Therefore, it is critical to accurately identify those at risk of falling so that preventive measures may be properly applied. Forty-nine participants (25 retrospectively identified fallers and 24 nonfallers) with a diagnosis of idiopathic PD were included in this study. Each was assessed using three categories of measurement tools: PD-specific scales (modified Hoehn and Yahr [HY] and Unified Parkinson's Disease Rating Scale [UPDRS]), balance-specific scales (Berg Balance Scale [BBS], Sensory Organization Test [SOT], and Activities-Specific Balance Confidence Scale [ABC]), and functional gait scales (Self-Selected Gait Velocity [SSGV], Dynamic Gait Index [DGI]), and a standardized obstacle course. Using discriminant function analysis, the BBS, HY, and UPDRS-Activities of Daily Living subscale (UPDRS-ADL) were found to be the best discriminators of faller...
Assessment of postural instability in patients with Parkinson’s disease
Experimental Brain Research, 2007
Postural instability is one of the most disabling features of idiopathic Parkinson's disease (PD). In this study, we focused on postural instability as the main factor predisposing parkinsonians to falls. For this purpose, changes in sway characteristics during quiet stance due to visual feedback exclusion were studied. We searched for postural sway measures that could be potential discriminators for an increased fall risk. A group of 110 subjects: 55 parkinsonians (Hoehn and Yahr: 1-3), and 55 age-matched healthy volunteers participated in the experiment. Their spontaneous sway characteristics while standing quiet with eyes open and eyes closed were analyzed. We found that an increased mediolateral sway and sway area while standing with eyes closed are characteristic of parkinsonian postural instability and may serve to quantify well a tendency to fall. These sway indices signiWcantly correlated with disease severity rated both by the Hoehn and Yahr scale as well as by the Motor Section of the UPDRS. A forward shift of a mean COP position in parkinsonians which reXects their Xexed posture was also signiWcantly greater to compare with the elderly subjects and exhibited a high sensitivity to visual conditions. Both groups of postural sway abnormalities identiWed here may be used as accessible and reliable measures which allow for quantitative assessment of postural instability in Parkinson's disease.
Archives of Physical Medicine and Rehabilitation, 2017
Objective-To determine the accuracy of inertial measurement unit data from a mobile device using the mobile device relative to posturography to quantify postural stability in individuals with Parkinson's disease (PD). Design-Criterion standard. Setting-Motor control laboratory at Cleveland Clinic. Participants-Fourteen mild to moderate individuals with PD and 14 healthy age-matched community dwelling controls completed the project. Interventions-Not applicable. Main Outcome Measures-Center of mass (COM) acceleration measures were compared between the mobile device and NeuroCom force platform to determine accuracy of mobile device measurements during performance of the Sensory Organization Test (SOT). Analyses examined test-retest reliability for both systems and sensitivity of: 1) the Equilibrium Score from the SOT and 2) COM acceleration measures from the force platform and mobile device to quantify postural stability across populations. Results-Metrics of COM acceleration from inertial measurement unit data and NeuroCom force platform were significantly correlated across balance conditions and groups (Pearson's r ranged from 0.35 to 0.97). The SOT Equilibrium Scores failed to discriminate individuals with PD and controls. However, the multi-planar measures of COM acceleration from the mobile device exhibited good to excellent reliability across SOT conditions and were able to discriminate individuals with PD and controls in conditions with the greatest balance demands.
Rapid assessment of postural instability in Parkinson’s disease (RAPID): a pilot study
European Journal of Neurology, 2011
The Fahn&amp;amp;amp;#39;s pull (or retropulsion) test is an item in the motor section of the Unified Parkinson&amp;amp;amp;#39;s Disease Rating Scale, which is used almost exclusively to classify postural instability in Parkinson&amp;amp;amp;#39;s disease (PD). However, the test is hard to standardize and is often performed incorrectly, making it hard to interpret. Moreover, it may not be safe to administer in patients who experience pain in the shoulders, neck, trunk and/or lower extremities. Identifying and grading postural instability in PD without requiring a physical challenge would not only be useful for the clinician but would assist patients and caregivers in its recognition. We propose the use of the rapid assessment of postural instability in Parkinson&amp;amp;amp;#39;s disease (RAPID) questionnaire as a non-physical assessment tool. We determined the associations between the pull test and items on a risk-assessment questionnaire that consisted of three parts: activities of daily living, fear of falling, and frequency of falling. Significant correlations were found between the pull test and the predictor variables, which ranged between 0.51 and 0.56 whilst the correlations amongst the predictor variables ranged between 0.58 and 0.70. The three parts of the questionnaire, when used in combination, produced a 96% sensitivity in the classification of postural instability. The RAPID questionnaire can be used as an adjunct to the pull test or solely if the pull test is contraindicated. It may also be possible to administer the questionnaire via the telephone or Internet. It is hoped that the rapid identification of postural instability would lead to fewer falls.