title: Functional electrical stimulation using microstimulators to correct foot drop: a case study.
abstract: This paper presents a case study that tested the feasibility and efficacy of using injectable microstimulators (BIONs) in a functional electrical stimulation (FES) device to correct foot drop. Compared with surface stimulation of the common peroneal nerve, stimulation with BIONs provides more selective activation of specific muscles. For example, stimulation of the tibialis anterior (TA) and extensor digitorum longus (EDL) muscles with BIONs produces ankle flexion without excessive inversion or eversion of the foot (i.e., balanced flexion). Efficacy was assessed using a 3-dimensional motion analysis of the ankle and foot trajectories during walking with and without stimulation. Without stimulation, the toe on the affected leg drags across the ground. BION stimulation of the TA muscle and deep peroneal nerve (which innervates TA and EDL) elevates the foot such that the toe clears the ground by 3 cm, which is equivalent to the toe clearance in the less affected leg. The physiological cost index (PCI) measured effort during walking. The PCI equals the change in heart rate (from rest to activity) divided by the walking speed; units are beats per metre. The PCI is high without stimulation (2.29 +/- 0.37, mean +/- SD) and greatly reduced with surface (1.29 +/- 0.10) and BIONic stimulation (1.46 +/- 0.24). Also, walking speed increased from 9.4 +/- 0.4 m/min without stimulation to 19.6 +/- 2.0 m/min with surface and 17.8 +/- 0.7 m/min with BIONic stimulation. These results suggest that FES delivered by a BION is an alternative to surface stimulation and provides selective control of muscle activation.
authors.affiliation: Faculty of Physical Education and Recreation, Centre for Neuroscience, University of Alberta, Edmonton, Alberta T6G 2H9, Canada. doug.weber@ualberta.ca
authors.forename: D J
authors.initials: DJ
authors.lastname: Weber
authors.forename: R B
authors.initials: RB
authors.lastname: Stein
authors.forename: K M
authors.initials: KM
authors.lastname: Chan
authors.forename: G E
authors.initials: GE
authors.lastname: Loeb
authors.forename: F J R
authors.initials: FJ
authors.lastname: Richmond
authors.forename: R
authors.initials: R
authors.lastname: Rolf
authors.forename: K
authors.initials: K
authors.lastname: James
authors.forename: S L
authors.initials: SL
authors.lastname: Chong
authors.forename: Aiko Kido
authors.initials: AK
authors.lastname: Thompson
authors.forename: J
authors.initials: J
authors.lastname: Misiaszek
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004599:Electric Stimulation Therapy / Q000295:instrumentation* / Q000379:methods*; D004567:Electrodes, Implanted; D020233:Gait Disorders, Neurologic / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D008297:Male; D008839:Microelectrodes