Dynamic Balance Is Related to Physiological Impairments in Persons With Multiple Sclerosis

Abstract

Objectives: To compare physiological impairments between persons with multiple sclerosis (MS) with a history of falls and persons with MS without a history of falls, and to investigate the association between physiological impairments and dynamic balance.

Design: Cross-sectional study.

Setting: University motion analysis laboratory.

Participants: Persons with MS (N=55; 27 recurrent fallers and 28 nonfallers). Participants were classified as fallers if they self-reported ≥2 falls in the previous 6 months.

Interventions: None.

Main outcome measures: Physiological impairment was assessed with sensorimotor delays, spasticity, plantar cutaneous sensation, and the sensory, cerebellar, and pyramidal subscales of the Expanded Disability Status Scale (EDSS). Dynamic balance was assessed using the average and variability of margin of stability and variability of trunk accelerations.

Results: Compared with nonfallers, fallers had lower plantar sensation, longer sensorimotor delays, more spasticity, and more impairment in the pyramidal and cerebellar subscales of the EDSS. Additionally, these impairments were all moderately to strongly correlated with worse dynamic balance.

Conclusions: This study highlights the multifactorial nature of instability in persons with MS. A better understanding of the physiological mechanisms of dynamic instability in persons with MS can be used to improve methods of monitoring disease progression, identifying which impairments to target through interventions, and appropriately evaluating intervention efficacy.

Keywords: Accidental falls; Multiple sclerosis; Rehabilitation; Walking.

Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Visual representation of the MoS calculation in the (A) anterior-posterior (AP) and in the (B) mediolateral (ML) direction. First the position of the center of mass (XCoM) and the anterior and lateral edges of the base of support (BoS) have to be defined and second the velocity of the CoM calculated (VCoM). The position of the CoM was estimated using the geometric center of the pelvic markers, and the edge of the base of support in the AP and ML direction was estimated using the toe and lateral MTP markers respectively. Note that the position and velocity of the CoM are two dimensional (AP and ML). The extrapolated center of mass (xCoM) is then calculated independently in the AP and ML direction, which includes the position and velocity of the CoM as well as the acceleration due to gravity (g) and length of the leg (L). MoS is then calculated as the distance between the xCoM and the edge of the BoS, again independently in the AP and ML directions.

Figure 2

Margin of stability values throughout the entire 3 minute walking trial for a representative non-faller (left) and faller (right).