FES supported gait of a hempilegic subject - a case study

Description

FES is a purposeful method to restore lost motor functions. The aim of this case study was to investigate the gait improvement by peroneal nerve stimulation with surface electrodes of a 50-year old man suffering from spastic hemiplegia and foot drop. For such a FES supported gait we were interested in suitable stimulation and control parameters for a more normal gait pattern at various walking speeds as well as in the additional range of motion and enhancement of walking distance. For the purpose of gait improvement a test-stimulator was developed. The device allows the manual adjustment of stimulation parameters (stimulus amplitude, duration and frequency)and control parameters (trigger delay and safety delay). The stimulation was applied on the peroneal nerve by surface electrodes placed in the area of the capitulum fibulae. In this way, the well known withdrawal reflex was elicited which produces a flexion in the knee joint as well as an extension in the hip and ankle joint. The control unit of the test-stimulator was equipped with a force sensor located under the heel of the healthy leg for triggering the stimulation. Trials performed on a treadmill were conducted by a physical therapist who corrected the subject´s locomotion while a technician adjusted stimulation and control parameters to maintain the achieved gait pattern. Results were gathered three times a week over a period of six months. Each walking speed demanded different stimulation and control parameters which had to be adapted in almost fixed time periods in order to maintain an optimized gait pattern. For example, when stimulus duration was too short, swing limb motion broke off too early, whereas a too long stimulus duration produced unfavorable strong swing limb motions. The distance walked within a fixed time span of 15 minutes increased from a start value of 100 meter to a length of 600 meter after six months. In this case study a significant improvement of the subject´s gait could be demonstrated. In case of the individual presented in this case study, peroneal nerve stimulation seems to be a very promising method to restore gait functions. Due to muscle re-education, prevention of disuse atrophy and increase in range of motion the distance walked increased significantly. However, reliable stimulation control without human support seems to be a very difficult task.

Period	4 Nov 1999 → 7 Nov 1999
Event title	EMB ECC
Event type	Other
Degree of Recognition	International