Gait Asymmetry Post-stroke

This thesis examined post-stroke gait asymmetry: a prevalent issue and one that has a number of associated negative consequences (e.g. challenged balance control, gait inefficiencies, increased risk of musculoskeletal injury to the non-paretic limb and decreased overall activity levels). This thesis is comprised of three studies that focused on 1) how gait symmetry should be measured, 2) how gait asymmetry may change in the long term post-stroke and 3) whether gait asymmetry is responsive to a rehabilitation intervention. A comparison of the most common expressions of spatiotemporal gait symmetry revealed that the simple symmetry ratio calculation was most appropriate on the basis of ease of interpretation and clinical usefulness. Swing time, stance time and step length were found to be the most useful gait parameters to assess for symmetry. Although related, swing time, stance time and step length ratios exhibit variation in the discrimination of post-stroke individuals, in their inter-relationships and in their relationship velocity. When when used together, swing time, stance time and step length asymmetry ratios may provide a complementary picture of the gait pattern and the quality of gait control. It was also demonstrated that swing time and stance time asymmetry were worse in later stages post-stroke when assessed cross-sectionally. In contrast, gait velocity did not exhibit this pattern. These results indicate that the control of gait (symmetry) may decline over time post-stroke, independent from the capacity for gait which remains constant (velocity). This dissociation in characteristics supports the concept that these two variables (symmetry and velocity) may represent separate features of post-stroke gait. Finally, individuals with sub-acute stroke are capable of altering the temporal symmetry of their gait in response to visual biofeedback. Individuals with sub-acute stroke differ in terms of the strategy they employ in response to biofeedback and the observed improvements in gait symmetry were not always achieved in the desired manner: increased use of the paretic lower extremity. This thesis presents new information regarding the asymmetrical nature of post-stroke gait. Future work may extend these findings to develop a comprehensive approach to gait measurement as well as gait interventions that encourage increased paretic limb use instead of compensatory behaviour.Ph