Rehabilitation
The WalkAide® Functional Electrical Stimulation System—A Novel Therapeutic Approach For Foot Drop in Central Nervous System Disorders
Michelle H Cameron, MD, PT
Neurologist, Multiple Sclerosis Center of Excellence West, Portland Veterans Affairs Medical Center, and Assistant Professor, Department of Neurology, Multiple Sclerosis Center of Oregon, Oregon Health and Science University
Abstract
Foot drop is the inability to voluntarily dorsiflex the ankle during the swing phase of gait. Foot drop decreases gait quality, limits mobility, increases fall risk, and greatly increases energy expenditure during walking. Traditionally, foot drop is treated with passive dorsiflexion support by an ankle foot orthosis (AFO) but today, functional electrical stimulation (FES) devices are available to promote comfortable, effective active dorsiflexion during gait for patients with central nervous system (CNS) causes of foot drop. The WalkAide® FES System’s unique control system, with tilt sensors to trigger electrical stimulation during swing phase, can help normalize gait and thus optimize safety, cosmesis, and energy efficiency in people with stroke, multiple sclerosis, cerebral palsy, and a wide range of other CNS disorders.
Keywords Brain injuries, cerebral palsy, electric stimulation therapy, gait, multiple sclerosis, stroke, walking
Disclosure: Michelle H Cameron, MD, PT, has received compensation for consulting from Teva Neurosciences, Mettler Electronics, Chattanooga Group, and Innovative Neurotronics. Received: September 20, 2010 Accepted: November 12, 2010 Citation: US Neurology, 2010;6(2):112–4 Correspondence: Michelle H Cameron, MD, PT, Department of Neurology, 3181 SW Sam Jackson Park Road, L226, Portland, OR 97239-3098. E:
cameromi@ohsu.edu
Support: The publication of this article was funded by Innovative Neurotronics, Inc. The views and opinions expressed are those of the author and not necessarily those of Innovative Neurotronics, Inc.
Foot drop is the inability to voluntarily dorsiflex the ankle and thereby lift the foot during the swing phase of gait. The condition is characterized by dragging the foot, which causes tripping or a steppage gait where the person raises their knee high during swing phase to avoid tripping over the hanging down foot and then, at the beginning of stance phase, the foot slaps the floor. Gait changes caused by foot drop decrease gait safety and efficiency, limit mobility, increase the risk for falls, and greatly increase energy expenditure during walking.1,2
Causes of Foot Drop
Foot drop is usually caused by damage to areas of the nervous system that control ankle dorsiflexion. Foot drop may be caused by central or peripheral nerve dysfunction and is common in patients with a wide variety of neurologic diagnoses including stroke, multiple sclerosis (MS), traumatic brain injury (TBI), spinal cord injury (SCI), cerebral palsy (CP), and peripheral neuropathy.
Treatment of Foot Drop
Traditionally, foot drop of all etiologies is treated with bracing using an ankle foot orthosis (AFO) (see Figure 1A). An AFO is a device, usually made of plastic, which wraps under the foot and behind the calf to passively assist ankle dorsiflexion. AFOs are simple devices that are
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Who Can Use the WalkAide® Functional Electrical Stimulation System for Foot Drop? FES is a new approach to treating foot drop. FES uses a low-level electrical current to stimulate peripheral motor nerves to produce active muscle contractions that promote functional movement. FES for foot drop involves stimulating the peroneal nerve to produce active dorsiflexion during the swing phase of gait. FES can be used to treat foot drop when the CNS is damaged and the peripheral nerves, neuromuscular junction, and muscles are intact. Therefore, FES is particularly effective for treating foot drop caused by CNS disorders such as stroke,6–8
MS,3,9–11 TBI,12 incomplete SCI,13–15 as well as other, less common CNS disorders. © TOUCH BRIEFINGS 2010 and CP16,17
widely available at relatively low cost, but they have a number of disadvantages and limitations. The passive dorsiflexion assistance they provide does not promote active use of remaining or recovering dorsiflexion function and also limits ankle range of motion. In addition, AFOs can be uncomfortable, bulky, and, if poorly fitted, produce areas of pressure and tissue breakdown. Many patients find AFOs so uncomfortable or unsightly that they do not use them. Research has therefore focused on developing alternative ways to treat foot drop. One of the most effective treatments for foot drop is functional electrical stimulation (FES, see Figure 1B).2–5
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