It is well known that improving community walking ability is one of the major goals in stroke rehabilitation. Even if motor recovery of the lower limbs does occur, the ability to walk in the community is often still impaired. This thesis set out to explore dual task ability after stroke in relation to community walking and explored dual task treadmill training in stroke survivors. In addition, functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) in stroke survivors during single and dual gait movements were performed to examine dual task effects on brain activation before and after dual task training. In a cross-sectional trial, 27 limited community walkers were compared to 23 moderate-to-full community walkers. A significant larger proportion of limited community walkers were not confident about walking in the community compared to moderate-to-full community walkers (p = 0.042). Moreover mean cognitive response during two-minute-walk with dual task was 11.17 ± 3.62 for limited walkers and 13.48 ± 2.43 for moderate-to-full community walkers (p = 0.014). In contrast, moderate-to-full community walkers displayed relative larger reductions in walking distance as a result of dual task in comparison to limited community walkers (p = 0.068). Consequently, a randomized controlled trial was performed in 50 chronic stroke survivors to explore to what extent 10 weeks of treadmill training with concurrent cognitive distraction in comparison to 10 weeks of treadmill training with no distraction would change community walking ability. Stroke survivors who received dual task treadmill training showed larger increases in two-minute-walk distance compared to the control group from baseline to follow with an effect size r of 0.24 and a Cohen’s d of 0.50. Significant group and time interactions were seen for physical activity scale assessments favouring the dual task training group (p = 0.029). In addition, on a modified version of the University of Alabama study of Aging Life Space Assessment questionnaire, stroke survivors in the dual task training group scored 54.76 ± 26.64 compared to 41.53 ± 20.88 in the control group at follow-up, (p = 0.086). Both training groups improved on walking performance and endurance during training. Feasibility of dual task training was good, with only l0% drop out for intention to treat. The final part of this thesis focussed on results from fMRI and fNIRS measures that were taken to explore brain activation patterns during single and dual task gait before and after dual task training. At baseline, decreases in brain activation were seen in prefrontal cortex areas during dual task treadmill walking compared to single task treadmill walking. Moreover, fMRI during pedal movements with a concurrent cognitive task showed decreased brain activation compared to pedal movement alone. Dual task trained stroke survivors showed a reduction in right occipital cortex activation during pedalling at follow-up compared to baseline whereas control trained stroke survivors showed increases in this area from baseline to follow-up with a significant difference of activation change between groups (p < 0.001). In addition, stroke survivors who had received dual task training showed significant reductions in brain activation during pedalling and increase in activation during dual task pedalling from baseline to follow-up. The results from the comparisons between limited community walkers and moderate-to-full community walkers suggested that different coping strategies might apply after stroke depending on gait speed, but also indicated that both type of community walkers had difficulties with dual task walking. Dual task treadmill training showed good feasibility and positive effects on walking endurance and performance as well as training without distraction. There were trends suggesting that stroke survivors who were already physically active and had recovered their walking up to a certain standard were more likely to improve their dual task walking distance after dual training. Brain imaging measures showed decreases in activation from single to dual task locomotor movements which may relate to reduced dual task ability in stroke survivors, but these changes did not correlate with changes in behavioural measures of dual task. The changes in response to training may relate to plasticity and a recovery of the automaticity of control of normal walking as a result of dual task training. This thesis has provided novel research, insights and practical implications for dual task training after stroke. More research is needed, for instance to explore the extent to which stroke survivors could benefit from dual task training in more real-life situations. The use of neuroimaging tools in stroke rehabilitation trials helps to understand how motor control mechanisms change in response to training and could add to tailor rehabilitation to the individual’s need.
Permanent link to this resource: https://doi.org/10.24384/g49b-j590
Meester, Daan Paul
Supervisors: Dawes, Helen; Johansen-Berg, Heidi; Al-Yahya, Emad
Oxford School of Nursing and Midwifery
Year: 2016
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