LATERAL POSTURAL SWAY DURING GAIT IN MODERATE-STAGE PARKINSON’S DISEASE: DOES IT MATTER FOR POSTURAL CONTROL?

Y. Kawami^1,2, Y. Nikaido³, S. Nose¹, M. Unekawa¹, K. Marumoto⁴, M. Kawami⁵, S. Matsugashita^2,5, T. Kozuki¹, T. Akisue²

Background: Balance impairment is a common problem frequently occurred in the patients with Parkinson’s disease (PD). PD patients often present impairment in voluntary weight shifting, mainly in the anterior-posterior direction. The lateral direction balance is often maintained in PD, but may differ according to the PD stage: in early stage lateral postural sway is normal, and in moderate-stage remains unknown. Postural sway in PD is one of risk factors associated with falls to address.

Purpose: The purpose of this study was to clarify postural control difference between PD patients classified as having lateral balance disorders (PLD) and with non-lateral balance disorders (PnLD).

Methods: Forty PD patients (69.8±5.7 years; 20 men and 20 women) and 20 age-matched healthy controls (HCs) were recruited for this study. Ethics commission approval, as well as written informed consent from all patients, was obtained. The tandem gait test was applied to all subjects. They were asked to take 10 tandem steps along a straight line and scored as follows: 0, no side steps; 1, single side step; 2, multiple side steps; 3, unable to take four consecutive steps. According to the mean score of three trials, PD patients were classified as PLD (score ≥ 1) or PnLD (score < 1). The primary outcome measure was ambulatory center of mass (COM) movement trajectory amplitude and its coefficient of variation (CV) during gait at their comfortable speed assessed by a triaxial accelerometer (MG-M1100-HW, LSI Medience, Japan). This device was attached to the low back at the L3 vertebra level with a belt. Descriptive statistics were compared between all PD patients and HCs using unpaired T-tests or Mann-Whitney's U test for continuous variables and chi-squared tests for non-continuous variables. To compare PLD with PnLD, similar analysis as indicated above were used. Statistical analyses were performed with R 2.8.1 at α level of 0.05.

Results: Score of the tandem gait test in PD patients was significantly higher than that in HCs (0.6±0.7 vs 0.2±0.3). In PD patients, 14 were classified as PLD and 26 as PnLD. Hoehn & Yahr score in PLD was significantly higher than that in PnLD (2.9±0.5 vs 2.5±0.4). Lateral movement trajectory amplitude (3.5±1.1 vs 2.8±1.2) and its CV (13.7±10.0 vs 16.8±9.6) was not significantly different between PD patients and HCs. In contrast, lateral movement trajectory amplitude in PLD was significantly higher than that in PnLD (4.3±0.8 vs 3.0±1.0). Moreover, its CV in PLD was significantly lower than that in PnLD (9.4±2.1 vs 16.0±11.7).

Conclusion(s): Our study suggests that PD patients with lateral balance disorders showed lateral postural sway during gait as compared with PD patients without lateral balance disorders. The low variability of lateral COM movements may compensate for imbalance due to lateral postural sway during gait in PD patients with lateral balance disorders.

Implications: Lateral postural sway in narrow stance may cause falls in moderate-stage PD patients. Correcting stance width and reducing lateral postural sway are important to improve lateral balance during gait and decrease fall risk.

Funding, acknowledgements: We received no financial support for this study.

Keywords: postural control, gait disorders, Parkinson’s disease

Topic: Neurology: Parkinson's disease

Did this work require ethics approval? Yes

Institution: Hyogo Prefectural Rehabilitation Hospital at Nishi-Harima

Committee: The Ethic Board of Kobe University Graduate School of Health Sciences

Ethics number: No. 794