Control of dynamic stability during gait termination on a slippery surface in Parkinson's disease

Abstract

Parkinson’s disease (PD) causes instability and difficulty adapting behaviour. To examine the effects of PD on adaptation to repeated, cued gait termination (GT) on a slippery surface, an unexpected slip perturbation during GT was followed by stops on a slippery surface under two conditions: planned over multiple steps and cued one step prior to GT. Measurements of feedforward and feedback-based responses were compared for group (PD versus control) and trial to determine 1) how PD affects the ability to integrate adaptive feedforward and feedback-based strategies to stopping on a slippery surface, 2) if adaptations can be maintained when the slippery stop is required within one step, and 3) if adaptations are not maintained, can behaviour be readapted with repeated exposure. Similar to controls, the PD group was able to adapt and integrate feedforward and feedback-based components of GT to increase stability under both stop conditions. Feedforward adaptations included a shorter, wider step, and a smaller anterior-posterior and larger lateral stability margin. Feedback-based adaptations included a longer, wider subsequent step. When cued to stop within one step, both groups maintained most of these adaptations: Foot angle at contact increased in the first cued stop but re-adapted with practice. PD did not affect the ability to adapt to gait termination on a slippery surface over multiple steps or within one step.

Is the Assessment of 5 Meters of Gait with a Single Body-Fixed-Sensor Enough to Recognize Idiopathic Parkinson’s Disease-Associated Gait?

“…Moreover, patients with PD perform decelerating gait phases with altered strategies 15. This is reflected in our study at the pre-last and last steps prior to the drop of AP velocity.…”

“…The assessment of the final gait phases is clinically interesting since the ability to stop forward progression of the body’s center of mass15 and the maintenance of balance16 are challenged at gait termination. Moreover, patients with PD perform decelerating gait phases with altered strategies 15.…”

Walking Stability During Normal Walking and Its Association with Slip Intensity Among Individuals with Incomplete Spinal Cord Injury

“…Kinematic variables such as average sagittal plane foot angle and MOS_AP at foot contact, average walking velocity, %DS, step width, and step length have previously been used as indicators of walking balance . These kinematic variables were calculated throughout all NW trials.…”

Adaptation of gait termination on a slippery surface in Parkinson's disease

“…PD has also been shown to affect the ability to quickly change motor programs 4–6 . Neural impairments caused by PD may limit the ability to switch between walking and stopping or to develop the feedforward adjustments required to maintain stability while stopping gait on a slippery surface 7 . Neurodegeneration caused by PD may further limit the ability to adapt behaviour when stopping on a slippery surface: The striatum, along with the cerebellum and select frontal lobe regions, is involved in motor learning and adaptation 8–10 as well as on-line modification of movements 10 like those seen during anticipation of a perturbation.…”

“…Past research has shown that participants with PD are able to integrate a feedback-based response while stopping on an unexpected, slippery surface 7 . This study, however, presents one of the first investigations into the adaptation of GT on a slippery surface in PD and addresses the following questions: 1) Can someone with PD integrate feedforward and feedback-based strategies to stop on a slippery surface?…”