Neural Prostheses and Gait Performance: Model-Based Strategies
Overview
- Phase
- Not Applicable
- Intervention
- Not specified
- Conditions
- Hemiplegia
- Sponsor
- VA Office of Research and Development
- Enrollment
- 9
- Locations
- 1
- Primary Endpoint
- Walking Stability and Speed
- Status
- Completed
- Last Updated
- 6 years ago
Overview
Brief Summary
The purpose of this research is to find the optimal patterns of functional electrical stimulation (FES) of muscles in the lower legs that will improve walking ability in those who have had a stroke and at the same time ensure walking stability. FES involves applying small electric currents to the nerves, which cause the muscles to contract.
FES research projects vary from simple investigations of the therapeutic effects of exercise on muscle function and skin health, to more complex studies of functional movements such as standing or walking.
Detailed Description
The study aims to find the optimal patterns of functional electrical stimulation (FES) of muscles in the lower legs that will improve walking ability in those who have had a stroke and at the same time ensure walking stability will be achieved through an analytical approach comprised of computational models and gait simulations to objectively determine patient-specific patterns of muscle activation. The investigators will develop a computer simulation of the dynamics of hemiplegic gait characterized by unilateral plantarflexor weakness. Then, the investigators will relate the results of the computer model results to real data collected from subjects with known plantarflexor weakness to provide a theoretical basis for improving gait efficiency and stability with FES.
Investigators
Eligibility Criteria
Inclusion Criteria
- •This study includes stroke survivors greater than 18 years of age, \>180 days from first clinical hemorrhagic or nonhemorrhagic stroke with:
- •Unilateral hemiparesis with sufficient endurance and motor ability to ambulate \>30 feet continuously without an AFO requiring no more than 25% physical help
- •Berg Balance Scale score \>23 without assistive devices
- •Standing ankle dorsiflexion strength of \<4/5
- •Foot-drop during ambulation with gait instability or inefficient gait defined as supervision need
- •Possible use of physical assistance or assistive device (cane, walker)
- •Evidence of foot-drop as seen by "dragging" or "catching" of affected toes during limb swing or circumducting affected limb
- •Vaulting of the unaffected limb or hiking the affected hip to clear toes.
- •Intact and electrically ex-citable lower motor neurons
- •Ankle dorsiflexion to at least neutral while standing with electrical stimulation of common peroneal and tibial nerves without painful hypersensitivity to stimulation
Exclusion Criteria
- •In addition to failure to meet the inclusion criteria, participants will be excluded from the study for the following:
- •Requires an ankle foot orthosis (AFO) to prevent knee flexion collapse in stance
- •Excessive edema of affected extremity
- •Absent sensation in affected limb
- •History of potentially fatal cardiac arrhythmias such as ventricular tachycardia, supraventricular tachycardia, and rapid ventricular response, atrial fibrillation with hemodynamic instability
- •Demand pacemakers or any implanted electronic systems
- •Pregnancy
- •Uncontrolled seizure disorder
- •Ipsilateral lower limb lower motor neuron lesion
- •Parkinson's disease
Outcomes
Primary Outcomes
Walking Stability and Speed
Time Frame: pre-stimulation (volitional) and post-stimulation (FES), day of the study
This was a feasibility study of computational models and gait simulations to objectively determine patient-specific patterns of muscle activation. We developed computer models and walking simulations of hemiplegic gait from 8 subjects. We related the model results (muscle activations) to the optimized data collected from hemiplegic subjects \& calculated the FES pattern to be delivered in 2 forms (open loop \& foot switch triggered). The primary outcome measure turned out to be the feasibility of the methods because after developing our computer modeling and computational optimization framework we could only test walking with the 2 forms of FES at the same preferred walking speed on a treadmill. Thus, the simulated walking speed and the real walking speed pre and post FES turned out to be the same. Walking stability was measured with variability in work performed at the ankle. The additional volitional and FES biomechanical data that were measured are listed in the secondary measures.
Secondary Outcomes
- Peak Ankle Power(Same day: pre-stimulation (volitional) and post-stimulation (FES), day of the study)
- Positive Ankle Work(Same day; pre-stimulation (volitional) and post-stimulation (FES), day of the study)
- The Impulse of the Anterior Ground Reaction Force Normalized by Body Mass.(Same day: pre-stimulation (volitional) and post-stimulation (FES), day of the study)