Continuous monitoring of turning in Parkinson's disease: Rehabilitation potential

Abstract

Background: Difficulty turning during gait is a major contributor to mobility disability, falls and reduced quality of life in patients with Parkinson's disease (PD). Unfortunately, the assessment of mobility in the clinic may not adequately reflect typical mobility function or its variability during daily life. We hypothesized that quality of turning mobility, rather than overall quantity of activity, would be impaired in people with PD over seven days of continuous recording.

Methods: Thirteen subjects with PD and 8 healthy control subjects of similar age wore three Opal inertial sensors (on their belt and on each foot) throughout seven consecutive days during normal daily activities. Turning metrics included average and coefficient of variation (CV) of: (1) number of turns per hour, (2) turn angle amplitude, (3) turn duration, (4) turn mean velocity, and (5) number of steps per turn. Turning characteristics during continuous monitoring were compared with turning 90 and 180 degrees in a observed gait task.

Results: No differences were found between PD and control groups for observed turns. In contrast, subjects with PD showed impaired quality of turning compared to healthy control subjects (Turn Mean Velocity: 43.3 ± 4.8°/s versus 38 ± 5.7°/s, mean number of steps 1.7 ± 1.1 versus 3.2 ± 0.8). In addition, PD patients showed higher variability within the day and across days compared to controls. However, no differences were seen between PD and control subjects in the overall activity (number of steps per day or percent of the day walking) during the seven days.

Conclusions: We show that continuous monitoring of natural turning during daily activities inside or outside the home is feasible for patients with PD and the elderly. This is the first study showing that continuous monitoring of turning was more sensitive to PD than observed turns. In addition, the quality of turning characteristics was more sensitive to PD than quantity of turns. Characterizing functional turning during daily activities will address a critical barrier to rehabilitation practice and clinical trials: objective measures of mobility characteristics in real-life environments.

Keywords: Parkinson’s disease; continuous monitoring; functional mobility.

Figure 1

Rotational rate of the lumbar (top), left and right foot (bottom). Blue, green and red traces are the gyroscope x, y and z-axes. Green areas represent periods in which the subject is sedentary; gray represents periods of turning, and white represent periods of walking in this 30 second-segment.

Figure 2

Turn Duration and Mean Velocity during the prescribed task at home (mean±STD). The prescribed task is depicted on the right panel.

Figure 3

Box-plot of Quantity (A) and Quality (B) of mobility measured across the 7 days of continuous monitoring.

Figure 4

Relationship between disease severity (measured by UPDRS Motor Score) and turning metrics during daily activities.

Figure 5

The CV of Turn Duration is plotted over the 7 days and every hour of the day for a representative healthy subjects, a mild PD and a moderate PD.

Figure 6

PD subjects exhibit more motor fluctuations during the day. Blue waves show the hourly fluctuation in step duration during turns of a patient with PD (blue), compared to a control subject (green), averaged across seven days.