Time-dependent changes in postural control in early Parkinson’s disease: what are we missing?

Abstract

Impaired postural control (PC) is an important feature of Parkinson's disease (PD) but optimal testing protocols are yet to be established. Accelerometer-based monitors provide objective measures of PC.We characterised time-dependent changes in PC in people with PD and controls during standing, and identified outcomes most sensitive to pathology. Thirty-one controls and 26 PD patients were recruited: PC was measured with an accelerometer on the lower back for 2 minutes (mins).Preliminary analysis (autocorrelation) showed 2 seconds (s) was the shortest duration sensitive to changes in the signal; time series analysis of a range of PC outcomes was undertaken using consecutive 2s windows over the test. Piecewise linear regression was used to fit the time series data during the first 30s and the subsequent 90s of the trial.PC outcomes changed over the 2mins, with the greatest change observed during the first 30s after which PC stabilised. Changes in PC were reduced in PD compared to controls, and Jerk was found to be discriminative of pathology.Previous studies focusing on average performance over the duration of a test may miss timedependent differences. Evaluation of time-dependent change may provide useful insights into PC in PD and effectiveness of intervention.

Longitudinal changes over thirty-six months in postural control dynamics and cognitive function in people with Parkinson's disease

“…A single tri-axial accelerometer (Axivity AX3, York, UK) on the lower back recorded acceleration at a sampling rate of 100 Hz [14].…”

“…The tri-axial accelerometry data were exported to the MATLAB ® (R2015a, Mathworks, Natick, MA) environment, downsampled to 10 Hz and rotated using the Moe-Nilssen transformation into anteroposterior, mediolateral and vertical accelerations [14,23]. No filtering was applied.…”

“…Clinically, assessment of postural instability is the Pull test, included in the Unified Parkinson's Disease Rating Scale (UPDRS III), which is insensitive to small changes in postural stability [12]. Objectively, postural stability has been assessed through centre of pressure (COP) parameters recorded from a force platform [13] and more recently, from body-worn monitors such as accelerometers [14][15][16]. The derived postural parameters are generally linear, providing information about signal characteristics averaged across time.…”

Acceptability and clinical trial feasibility evaluation of auditory rhythmical cueing to improve gait and physical activity in community dwelling stroke survivors (ACTIVATE): study protocol for a pilot randomised controlled trial

“…Recorded AX3 accelerations store locally on the device's internal memory and then downloaded upon the completion of each walking trial. The feasibility, validity and reliability of the AX3 accelerometer has been previously demonstrated for measuring spatio-temporal aspects of gait and physical activity in a stroke population in the clinic and the community 35 .…”

Parkinsonian Balance Deficits Quantified Using a Game Industry Board and a Specific Battery of Four Paradigms

“…In patients with movement disorders, both abnormal static posture (Del Din et al, 2016) and pathological dysfunctions in sensory-motor circuitry contribute to the loss in balance function and the increased risk for fall (Gatev et al, 2006; Darbin, 2012; Darbin et al, 2013a; Schrag et al, 2015). The integration of vestibular information involves a large circuitry.…”