Quantifying the Role of Sensory Systems Processing in Post-Stroke Walking Recovery

Walking impairment after a stroke impacts nearly 66% of stroke survivors and is a rising cause of morbidity worldwide. Despite ongoing efforts to increase the quality and delivery of rehabilitative care, less than ten percent of stroke survivors ever achieve walking independence within the community and are at higher risk of falls, fractures, rehospitalization. Several factors may lead to walking impairment, but the two most prevalent causes are lower extremity asymmetry and imbalance. Herein, the investigators propose backward locomotion treadmill training (BLTT), as a promising approach for walking rehabilitation in stroke survivors.

Hence, our central hypothesis is that BLTT facilitates sensory signaling, leading to an improvement in walking speed. The investigators have preliminary proof of technique and feasibility data suggesting that BLTT is safe and feasible for stroke patients, with our results showing clinically meaningful improvement in overground walking speed after just six training sessions, with retention at the two-week follow-up. The next logical step in planning toward a future definitive clinical trial is to determine its preliminary efficacy compared with conventional forward walking treadmill training (FLTT) as control.

The investigators plan to test the preliminary efficacy of BLTT by conducting a prospective, randomized, blinded-endpoint, pilot study of 40 individuals with residual mild-moderate gait impairment, >6 months post-stroke, to BLTT (n=20) versus FLTT (n=20), for nine 30-minute training session (3 sessions/week). The investigators will utilize well-validated behavioral measures in stroke recovery and rehabilitation to test the following Aims:

Aim 1. Determine the training-related effects of BLTT on overground walking speed (primary outcome) To achieve this aim, the investigators will compare the Pre-Post change in walking speed [10- meter walk test (10MWT)] between groups. Our working hypothesis 1 is that BLTT will increase walking speed (>0.13m/s), compared to the control group (FLTT).

Aim 2. Determine the effects of training on walking symmetry, proprioceptive signaling, and dynamic balance. The Zeno Walkway Gait Analysis software will capture Pre-Post changes in temporal gait symmetry index during the 10-MWT. Working hypothesis 2a: BLTT will be associated with a favorable improvement in the temporal symmetry index score. Proprioception and spinovestibular function will be measured with the modified Sensorineural Integration Test (mSIT), and dynamic balance will be assessed with the completion time on the instrumented Timed Up & Go (i-TUG). Working hypothesis 2b and c: BLTT will be associated with a favorable improvement Pre-Post mSIT(b) and completion time on the i-TUG (c).

Inclusion criteria

• 18-80 years of age
• Ability to maintain ≥0.3mph speed for 6-minute interval on the treadmill
• Able to walk independently (cane and hemi-walker acceptable)
• Ambulate >10 meters over ground with the Free Step Harness System (as a safety precaution)
• Discharged from formal rehabilitation.

Exclusion criteria

• Walking speed <0.4m/s (per 10MWT comfortable)
• Unstable cardiac status which would preclude participation in a moderate-intensity exercise program
• Significant language barrier which might prevent the participant from following instructions during training and testing
• Adverse health condition that might affect walking capacity (severe arthritis, significant pulmonary disease significant ataxia, or severe hemi-neglect)
• Severe lower extremity spasticity (Ashworth >2)
• Depression (>10 on the Patient Health Questionnaire, if untreated).