Date Published: June 7, 2018
Publisher: Public Library of Science
Author(s): Gautam Adusumilli, Samantha Lancia, Victoria A. Levasseur, Vaishak Amblee, Megan Orchard, Joanne M. Wagner, Robert T. Naismith, Antony Bayer.
The standard functional tool for gait assessment in multiple sclerosis (MS) clinical trials has been the 25-Foot Timed Walk Test, a measure of gait speed. Straight-line gait assessment may not reflect adequately upon balance and coordination. Walking tests with turns may add additional information towards understanding gait and balance status, and be more reflective of ambulation in the community. Understanding the impact of turn parameters on patient-reported outcomes of balance and walking would help MS clinicians better formulate treatment plans for persons with gait limitations. In this study, ninety-one persons with MS (Expanded Disability Status Score; EDSS, range: 0–6.5) were enrolled in an initial cross-sectional study. Twenty-four subjects (EDSS, range:1.0–6.0) completed a follow-up visit an average of 12 months later. Spatiotemporal gait analysis was collected at both visits using APDM Opal wireless body-worn sensors while performing the Timed-Up-and-Go (TUG) and 6-Minute Walk Test (6MWT). For both cross-sectional and longitudinal data, regression analyses determined the impact on the addition of turning parameters to stride velocity (SV), in the prediction of self-reported balance confidence (Activities-Specific Balance Confidence Scale (ABC)) and walking limitation (12-item Multiple Sclerosis Walking Scale (MSWS-12)). The addition of 6MWT peak turn velocity (PTV) to 6MWT SV increased the predictive power of the 6MWT for the ABC from 20% to 33%, and increased the predictive power from 28% to 41% for the MSWS-12. TUG PTV added to TUG SV also strengthened the relationship of the TUG for the ABC from 19% to 28%, and 27% to 36% for the MSWS-12. For those with 1 year follow-up, percent change in turn number of steps (TNS%Δ) during the 6MWT added to 6MWT SV%Δ improved the modeling of ABC%Δ from 24% to 33%. 6MWT PTV%Δ added to 6MWT SV%Δ increased the predictive power of MSWS-12%Δ from 8% to 27%. Conclusively, turn parameters improved modeling of self-perceived balance confidence and walking limitations when added to the commonly utilized measure of gait speed. Tests of longer durations with multiple turns, as opposed to shorter durations with a single turn, modeled longitudinal change more accurately. Turn speed and stability should be qualitatively assessed during the clinic visit, and use of multi-faceted tests such as the TUG or 6MWT may be required to fully understand gait deterioration in persons with MS.
Gait impairments are well-documented in multiple sclerosis (MS). Persons with MS (PwMS) have demonstrated decreased straight-line velocity and step length, lower limb swing asymmetry, reduced maximum hip and knee extension, and an overall decrease in propulsive force during walking . The Timed 25-Foot Walk (T25FW), an objective measure of straight-line gait speed, is considered one of the gold standard measures for research and clinical gait assessment in PwMS . While walking speed may reflect changes in lower extremity weakness and spasticity, it may not reflect real world walking impairment. A recent study on the T25FW, Timed-Up and Go (TUG), and Two-Minute Walking Test (2MWT) reported that gait variability in MS patients with a high rate of falls was captured least well by the T25FW . Falls were highly correlated to deteriorations in balance and coordination, and the TUG test, consisting of turns and other postural transitions in addition to straight walking, was more strongly associated with these changes . Turns while ambulating may therefore be important to evaluate balance and coordination.
This study demonstrated that turns are an important predictor of patient-reported balance confidence and walking limitation, as measuring turns improves the correlation between gait-based outcome measures and patient report of walking and balance limitations. While stride velocity parameters did correlate with the patient report of home and community ambulation, the clinical relationship was enhanced with the turning component. Consistent results were found in the cross-sectional analysis, whether using a test consisting of a single turn (TUG) or multiple turns (6MWT). For the longitudinal analysis, multiple turns appeared to more accurately capture the impairment for the 6MWT over the TUG. Although the longitudinal cohort was smaller than the cross-sectional cohort, this preliminary result suggests that including several turns could be a more sensitive way to better capture changes in balance confidence and walking limitation.
Turns are an important predictor of patient-reported balance confidence and walking limitation. Although clinical disability is indeed better represented by a longer duration walking test, the TUG contains more information than the current gold-standard 25-Foot Walk Test and is of similar testing duration, thus making it a practical alternative for clinics. Further work must be done longitudinally on the TUG, 2MWT, and 6MWT, and more cost-effective technology to quantify turns must be found. In the interim, obtaining TUG duration as an outcome variable, and documenting TNS during gait assessment would be of the most value for MS clinics.