Effect of FES Interventions on Gait Dynamics in Stroke Population

Hemiplegia with associated foot drop occurs in 50% of the stroke survivors and frequently
impairs an individual's ability to walk. Functional Electrical Stimulation (FES) based
neuroprosthetic devices have been developed to correct foot drop. The efficacy of these
devices were initially examined by Liberson el al. who demonstrated that electrical
stimulations could assist in restoring functional movements in paralyzed limbs. In addition
to assistance with foot drop, these devices have showed significant improvements in
biomechanical variables such as walking speed, distance, stride length and physiological
cost for individuals with stroke. In order to comprehensively understand the effect of
electrical stimulations on gait recovery, it is critical to analyze the dynamic aspects of
gait and measure gait variability during the functional electrical stimulation intervention.
In the proposed investigation, we will determine the 'gait symmetry' of FES assisted walking
using bilateral cyclograms of the ankle and knee over a period of 6 months. This novel
approach will account for the dynamics and complexity of balance by measuring the deviations
of joints from a line of symmetry at every instance of gait cycle and will provide better
measure of gait symmetry. Utilization of this outcome measure will allow us to understand
the role of electrical stimulation at ankle and how this effect gets translated to the knee
and hip joints during walking. The changes in the surface electromyograms (EMGs) of
selective muscle groups will demonstrate how FES can contribute to muscle re-training after
stroke. We will use advanced signal processing algorithms to remove FES artifact from the
EMG signal in order to comprehensively analyze the carry-over effect of the FES
intervention. Finally, we will employ Principal Component Analysis (PCA) - an advanced data
mining technique to track and quantify the overall gait recovery process of individuals with
stroke using pattern classification algorithms. The gait symmetry measure and the EMGs will
be statistically classified to see their clear separation at baseline and 6 month intervals.
This classification will allow us to identify the individuals who were most responsive to
the intervention. This information is critical and will allow researchers and clinicians to
re-strategize the rehabilitation process. Such scientific evaluation will provide the base
for further development and implementation of FES devices or technologies, thus supporting
the NINDS' fundamental goal of translating basic and clinical discoveries into better ways
to treat neurological disorders.

Inclusion Criteria:

- Must have sustained a stroke at least 6 months prior to study enrollment

- Must have hemiplegia with foot drop

- Must have positive response to peroneal nerve stimulation resulting in adequate
dorsiflexion of the ankle

- No current usage of Functional Electrical Stimulations for the treatment of foot drop

- No history of injury or pathology to the unaffected limb

- Must be able to walk independently or with close supervision, for 25 feet without
WalkAide or any assistive device

Exclusion Criteria:

- Orthopedic pathologies or history that will interfere with ambulation or limit the
range of motion of the lower limbs

- Neuromuscular pathologies or history that will interfere with neuromuscular function,
ambulation, or limit the range of motion of the lower limbs (e.g., myasthenia gravis,
Eaton-Lambert syndrome, amyotrophic lateral sclerosis)

- Neurological pathologies (e.g., multiple sclerosis)

- Serious lung or heart conditions that could severely limit their ability to walk

- Current involvement in any other study that can affect the results of this study

- Inability or unwillingness to comply with study procedures, follow-up requirements
and follow instructions