Virtual Reality Augmented Gait Adaptation in Stroke Survivors

The major problem in stroke survivors that is being addressed in this research project is walking asymmetry, i.e., difference between the legs during walking (e.g. steps on the more affected side are longer than the other). A potential solution to this problem is using new technology like virtual reality during walking training to make stroke survivors have a better sense of their asymmetry. A second problem that we aim to address in this study is whether asymmetry is accurately felt by the stroke survivors and how we can address it. Our ongoing work on the effects of virtual reality on learning new walking tasks in stroke survivors indicates that virtual reality maybe particularly important for those with walking asymmetry. In this study, we plan to recruit stroke survivors who have such asymmetries during walking and have them learn a new walking task in virtual reality. We will also test the stroke survivors to determine if there is a relationship between how well they learn the new task with their ability to feel asymmetry accurately.

Stroke survivors show a deterioration in bilateral coordination during gait that impacts functional mobility and quality of life. Such deterioration includes spatial (e.g. step length) and temporal (e.g. step time) inter-limb asymmetries during walking (gait asymmetry). While restoration of gait symmetry through adaptive exercise as in split-belt training is an answer, it is compounded by deficits of perception that is common in stroke survivors. One solution to this problem is the use of augmented visual feedback such as virtual reality (VR). Such augmented visual inputs during training can help remove sensory conflicts that commonly exist during gait rehabilitation (e.g. static visual input versus motion perception through proprioceptive input during treadmill walking). The PI's ongoing research investigating the effects of VR on gait adaptation in stroke survivors indicates that the impact of VR is dependent on the subject's baseline gait asymmetry such that the effect of VR is potentially higher in those who have large baseline asymmetries. Therefore, in the current proposal, to determine if this hypothesis is correct, chronic stroke survivors who are above and below a specific asymmetry threshold will be recruited and assessed for the effect of VR on a split-belt treadmill paradigm. In the second aim, the effect of VR on the transfer of split-belt adaptation to a preferred walking trial will be assessed. Since stroke survivors also suffer from major perceptual deficits related to symmetry, in the third aim, the effect of VR on gait adaptation on four groups of stroke survivors will be analyzed those with deficits only in perceiving visual asymmetry, only gait asymmetry, both deficits or neither.

Chronic stroke survivors will be screened and assigned to either a Symmetric or Asymmetric group based on inter-limb step length and/or step time asymmetry at baseline. Each subject will be randomly assigned to perform a split-belt adaptation protocol in either a VR or a Non-VR environment.

In this control arm, stroke survivors who walk symmetrically will walk on a split-belt treadmill in a non-virtual reality environment.

In this experimental arm, stroke survivors who walk symmetrically will walk on a split-belt treadmill in a VR - virtual reality environment.

In this control arm, stroke survivors who walk asymmetrically will walk on a split-belt treadmill in a non-virtual reality environment.

In this experimental arm, stroke survivors who walk asymmetrically will walk on a split-belt treadmill in a VR - virtual reality environment.

Inclusion Criteria: adults > 21 years diagnosed with supratentorial ischemic or hemorrhagic stroke single, unilateral stroke stroke incident > 3 months duration. ability to stand unsupported without an assistive device walk 10m without therapist assistance, ability to follow instructions (Folstein Mini-Mental exam score ≥ 24) Exclusion Criteria: recurrent stroke hip fracture myocardial infarction < 20/40 corrected vision any condition that can affect walking ability to complete the experiment successfully (e.g. neglect, Parkinson's disease, vestibulopathy, peripheral nerve pathology).