Neural Prostheses and Gait Performance: Model-Based Strategies

Not Applicable

Completed

Conditions: Hemiplegia

Registration Number: NCT00991406

Lead Sponsor: VA Office of Research and Development

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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 9

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
Adequate social support and stability
Medically stable with intact skin in affected lower limb
Willingness to comply during research procedures
No systemic co-morbidities
No history of potentially fatal cardiac arrhythmias i.e. ventricular tachycardia, supraventricular tachycardia and rapid ventricular response atrial fibrillation with hemodynamic instability
No psychological problems or chemical dependency
No acute medical complications such as depression or chronic anxiety requiring long term pharmacological therapy. Able-bodied controls must be of similar age, body mass and stature as those with hemiparesis and must be free of any medical and disabling orthopedic problems.

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
Spinal cord injury
Traumatic brain injury
Multiple sclerosis
Ankle plantar flexor contraction
Severely impaired cognition and communication
Painful hypersensitivity to neuromuscular stimulation of common peroneal nerve
Knee hyperextension (genu recurvatum) that cannot be adequately corrected with peroneal nerve stimulation
History of botulinum toxin to the lower extremity within the prior three months.

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Primary Outcome Measures

Name	Time	Method
Walking Stability and Speed	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 Outcome Measures

Name	Time	Method
Peak Ankle Power	Same day: pre-stimulation (volitional) and post-stimulation (FES), day of the study	This is the peak ankle power during walking normalized by body weight.
Positive Ankle Work	Same day; pre-stimulation (volitional) and post-stimulation (FES), day of the study	This is the amount of positive work performed by the ankle during walking normalized by body mass.
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	The is the magnitude of ground reaction force over time per step in the anterior direction during walking.

Trial Locations

Locations (1): Louis Stokes VA Medical Center, Cleveland, OH
🇺🇸
Cleveland, Ohio, United States
Louis Stokes VA Medical Center, Cleveland, OH
🇺🇸Cleveland, Ohio, United States