Evaluating balance disorders with different levels of walking impairment in Multiple Sclerosis: correlation between IMU-based parameters and clinical scales

Abstract

Gait and balance disorders are marked functional deficits in people with multiple sclerosis (MS) [1]. Walking limitations are frequently reported in people with MS despite the Expanded Disability Status Scale (EDSS) indicates normal walking autonomy [2]. To better identify changes due to disease severity, a combined instrumental assessment based on inertial measurement units (IMUs) and clinical scales during walking paths have been recommended [3,4]. The aim of this study is to verify the correlation between objective data extracted from IMUs during walking and scores of a routinely performed clinical scale in patients with MS with different levels of walking impairment. Thirty-three patients with MS (Class 1– mild disability, n=4, 2 F, 53.8±1.3 y, EDSS 0–1.5; Class 2– mild to moderate disability, n=16, 12 F, 50.5±9.7, EDSS 2.0–4.0; Class 3– moderate disability, n=13, 10 F, 49.5±10.4, EDSS 4.5–6.5) participated in this study. All participants performed a 10-meter Walk Test (10mWT) and a Figure-of-8 Walk Test (F8WT) [3] while wearing five IMUs (APDM, Opal, 128 Hz) on both lateral malleoli, pelvis, sternum, and head. Stride segmentation was performed from leg IMUs. Spatio-temporal (ST) parameters (stride frequency-SD and duration-SD) along with gait quality indices related to stability (Root Mean Square-RMS and Attenuation Coefficients-AC), symmetry (improved Harmonic Ratio-iHR), and smoothness (Spectral Arc Length-SPARC) of gait were obtained. In addition, the Mini-Balance Evaluation Systems Test (Mini-BESTest) was also administered. The correlation between biomechanical parameters and the clinical scale was investigated through Pearson’s correlation analysis after verifying for normal data distribution. Significant correlations (moderate to high correlations) were observed between spatio-temporal, stability, symmetry, and smoothness gait parameters and MiniBESTest, especially for patients with higher EDSS (Class 2&3) and for the F8WT (Table 1). In the clinical setting, instrumental gait analysis with IMUs is a useful tool for evaluating balance disorders in patients with MS, especially when clinical scales are not able to detect subtle impairments as in the earliest stages of the disease (Class 1,EDSS ≤ 1.5). Despite linear walking highlights several correlations between the clinical scale and dynamic gait indices, the F8WT confirms to be highly discriminant of the different levels of walking impairment since more challenging [3]. The IMU-based approach could be therefore integrated in clinical practice to quantify gait impairments when undetectable with a standard clinical measure.