The quality of turning in Parkinson’s disease: a compensatory strategy to prevent postural instability?

Abstract

BackgroundThe ability to turn while walking is essential for daily living activities. Turning is slower and more steps are required to complete a turn in people with Parkinson’s disease (PD) compared to control subjects but it is unclear whether this altered strategy is pathological or compensatory. The aim of our study is to characterize the dynamics of postural stability during continuous series of turns while walking at various speeds in subjects with PD compared to control subjects. We hypothesize that people with PD slow their turns to compensate for impaired postural stability.MethodMotion analysis was used to compare gait kinematics between 12 subjects with PD in their ON state and 19 control subjects while walking continuously on a route composed of short, straight paths interspersed with eleven right and left turns between 30 and 180°. We asked subjects to perform the route at three different speeds: preferred, faster, and slower. Features describing gait spatio-temporal parameters and turning characteristics were extracted from marker trajectories. In addition, to quantify dynamic stability during turns we calculated the distance between the lateral edge of the base of support and the body center of mass, as well as the extrapolated body center of mass.ResultsSubjects with PD had slower turns and did not widen the distance between their feet for turning, compared to control subjects. Subjects with PD tended to cut short their turns compared to control subjects, resulting in a shorter walking path. Dynamic stability was smaller in the PD, compared to the healthy group, particularly for fast turning angles of 90°.ConclusionsThe slower turning speeds and larger turning angles in people with PD might reflect a compensatory strategy to prevent dynamic postural instability given their narrow base of support.

Pharmacological treatment in Parkinson's disease: Effects on gait

“…The number of steps taken to complete the turn, speed of turning, dynamic postural stability (i.e. relation of the body center of mass (CoM) to the edge of foot support) and coordination of head-trunk-feet motion are used to quantify turning [15]. …”

“…In addition, turning in people with PD is characterized by slow, jerky turning and additional steps are needed to complete the turn [39-41]. When people with PD are asked to turn quickly, they become unstable as they spend more time than control subjects with their body CoM outside their base of foot support [15]. …”

Algorithm for Turning Detection and Analysis Validated under Home-Like Conditions in Patients with Parkinson’s Disease and Older Adults using a 6 Degree-of-Freedom Inertial Measurement Unit at the Lower Back

“…It requires multi-limb coordination and continuous change of center of mass (1) and thus provides information about dynamic balance aspects (2). It is, therefore, not surprising that turning deficits are associated with increased risk of falling (3, 4), with consequences such as fractures (5) and increased risk of mortality (6).…”

Auto detection and segmentation of daily living activities during a Timed Up and Go task in people with Parkinson’s disease using multiple inertial sensors

“…As a comparison, our algorithms were able to detect these common activities with 100% accuracy. Furthermore, we also expanded to the detection of turning, which can provide important indication of mobility in people with PD [30, 31, 43–45]. …”

“…have been shown to change significantly in people with PD when compared to healthy older adults during common daily living activities. Furthermore, turning step [30] and speed [31] have been extracted from inertial sensors to evaluate the motor quality of people with PD during turning task.…”