Accelerometry-Based Gait Analysis and Its Application to Parkinson's Disease Assessment— Part 1: Detection of Stride Event

An ambulatory gait analysis method using body-attached gyroscopes to estimate spatio-temporal parameters of gait has been proposed and validated against a reference system for normal and pathologic gait. Later, ten Parkinson's disease (PD) patients with subthalamic nucleus deep brain stimulation (STN-DBS) implantation participated in gait measurements using our device. They walked one to three times on a 20-m walkway. Patients did the test twice: once STN-DBS was ON and once 180 min after turning it OFF. A group of ten age-matched normal subjects were also measured as controls. For each gait cycle, spatio-temporal parameters such as stride length (SL), stride velocity (SV), stance (ST), double support (DS), and gait cycle time (GC) were calculated. We found that PD patients had significantly different gait parameters comparing to controls. They had 52% less SV, 60% less SL, and 40% longer GC. Also they had significantly longer ST and DS (11% and 59% more, respectively) than controls. STN-DBS significantly improved gait parameters. During the stim ON period, PD patients had 31% faster SV, 26% longer SL, 6% shorter ST, and 26% shorter DS. GC, however, was not significantly different. Some of the gait parameters had high correlation with Unified Parkinson's Disease Rating Scale (UPDRS) subscores including SL with a significant correlation (r = -0.90) with UPDRS gait subscore. We concluded that our method provides a simple yet effective way of ambulatory gait analysis in PD patients with results confirming those obtained from much more complex and expensive methods used in gait labs.

The purpose of this research was to assess the ability of trunk acceleration measures to discriminate between the walking patterns of elderly individuals with and without stability problems. Twenty volunteers, aged 65 and over, and 19 younger volunteers, all of whom were free of abnormalities or problems that could affect their gait, were recruited for this study. A triaxial accelerometry system was mounted directly over the spine of the upper trunk. Forty seconds of walking data were collected. Using a heel contact switch to define the beginning of the gait cycle, harmonic analyses of each of the 3 acceleration measures were performed on 10 strides. The ratio of summed amplitudes of the even and odd harmonics (index of smoothness) was calculated for each stride and averaged across 10 strides. One-way analyses of variance were used to compare harmonic ratios between groups. Relationships between variables were tested using a correlation analysis. The scores of individuals with stability problems were shown to be significantly different from the younger controls and the older individuals without stability problems for the anterior/posterior and vertical harmonic ratio and peak acceleration measures. The results from this research demonstrate that trunk acceleration measures offer the possibility of being able to identify unstable elderly individuals.