The Role of Arm Swing on Dynamic Stability in People with Parkinson’s Disease
Creators: name: Siragy, Tarique
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 2021
Subjects: Parkinson's Disease
Gait
Perturbations
Virtual Reality
Arm Swing

description: Introduction: Idiopathic Parkinson’s Disease is a multisystem neurodegenerative disease that is characterized by asymmetric impairment in regions of the midbrain, forebrain, and brainstem. Of the known neurodegenerative diseases, Parkinson’s is the second most commonly diagnosed worldwide with a global prevalence expected to reach 9 million individuals by 2030. As fall rates range between 35-68% annually, falling during walking is amongst the primary concerns for this demographic. Interestingly, despite the close association between loss of arm swing (due to Parkinson’s Disease) and future falls, evidence to-date has not examined the effect different arm swing conditions have on walking stability during unperturbed and perturbed (cognitive and mechanical) conditions. Dynamic stability research in this demographic is further limited in that evidence examining differences between the least and most affected leg is sparse. Research Objectives: To examine the differences between natural arm swing (unrestricted) and when arm swing was physical restricted (restricted) in people with Parkinson’s Disease. The effect of arm swing was assessed when people with Parkinson’s Disease walked in steady-state, dual-task, destabilizing terrains as well as in response to slips. Additionally, this thesis examined differences between the least and most affected sides, during the aforementioned conditions, that stem from the asymmetric progression in Parkinson’s Disease. Methods: Twenty individuals with Parkinson’s Disease were recruited for this research. Individuals walked on a CAREN-Extended System with unrestricted (natural) and restricted (absent) arm swing. Arm conditions were combined with steady-state walking, walking while performing a secondary dual-task, walking on minor destabilizing environments (hilly, rocky and mediolateral translational), and in response to slips for the heel-strikes of the perturbed (slipped) leg and recovery (contralateral) leg. The minor destabilizing terrains were assessed separately to steady-state walking for the arm swing condition resulting in three types of analyses (arms-rocky, arms-rolling hills, and arms-mediolateral). Data were processed in Vicon, Visual 3D, and OpenSim before being exported to Matlab to calculate dynamic stability (Margin of Stability, Harmonic Ratios and Coefficient of Variation), average spatiotemporal parameters, as well as trunk linear and angular velocities. Statistical analyses were conducted in SPSS with a significance level set a priori at (p&lt;0.05). Results: During unperturbed walking with the restricted arm swing condition, compared to unrestricted, average trunk angular velocity increased in the transverse plane while instantaneous linear velocity at heel-strike decreased in the sagittal plane. Further, on the least affected leg, the Margin of Stability increased, average step length decreased, and coefficient of variation for step length increased. Contrastingly, step time coefficient of variation increased in the most affected leg. In the presence of the dual-task, average angular velocity in the frontal plane increased, average step time decreased (most affected leg), and step width coefficient of variation increased (bilaterally). Compared to unrestricted arm swing, restricted arm swing reduced average step length (arm-rolling hills) and time (arm-rocky), and increased COV step time (arm-rolling hills). The arm-rolling hills analysis revealed that the most affected leg had a shorter step length than the least affected. The destabilizing surface effects revealed that during the arm-rolling hills and arm-rocky analyses step time decreased, step width increased, and the COV for step time, length and width increased. No main effects occurred for the arm-mediolateral analysis. Additionally, when comparing the arm swing conditions in response to a slip, the restricted arm swing condition, compared to unrestricted, caused a faster step time during the slipped step. Compared to the most affected leg, the least affected had a wider step width during the slipped step. During the recovery step, the least affected leg had a larger anteroposterior Margin of Stability and longer step time than the most affected. Conclusion: The findings revealed that when people with Parkinson’s Disease walk without arm swing, trunk rotational velocity increases which internally perturbs gait. This destabilization elicited unique responses from dynamic stability metrics that were specific to the terrain encountered. Since Parkinson’s Disease primarily affects movement timing, the results suggest that loss of arm swing is particularly perturbing to foot placement timing while changes in spatial foot placement reflect compensation to maintain an existing level of global dynamic stability and symmetry. Additionally, the evidence indicates that the independent behavior of the least and most affected leg respond uniquely to loss of arm swing. However, as people with Parkinson’s Disease adjust the least affected leg’s foot placement to mirror the contralateral leg, functional interlimb differences may only be revealed when individuals encounter perturbations.