Multiple sclerosis (MS) is a condition that involves damage to the myelin sheath that covers nerve fibers in the central nervous system. The condition can cause physical disabilities, including trouble with walking. Some people with MS will experience foot drop — difficulty lifting the front part of the foot while walking. Individuals with foot drop may need to raise their leg higher than normal when walking to prevent their toes from dragging on the floor.
A neurologist might recommend a brace called an ankle-foot orthosis to manage walking with foot drop. Alternatively, they may recommend a functional electrical stimulation (FES) device, a wearable device that provides a type of muscle and nerve stimulation.
Understanding FES and its benefits can help empower a person living with MS to make decisions about their treatment. Foot drop can be frustrating and negatively impact a person’s life. FES represents a viable treatment option for the condition, which may help restore mobility and associated independence.
An ankle-foot orthosis provides support at the ankle, foot, and knee while preventing your toes from dragging while you walk. Although this can be helpful in treating foot drop, it can contribute to some muscle atrophy because it reduces the contraction of your calf muscles as you walk. An ankle-foot orthosis can also be uncomfortable and difficult to fit under clothing and into shoes.
An FES device, on the other hand, uses small electrical charges to stimulate a muscle that has been weakened due to damage in the spinal cord or brain. Upon stimulation, the muscle can move similarly to the way it moved before damage occurred. FES has been shown to improve walking performance and gait speed for people living with MS.
Generally, people wear an FES device strapped in place just below their knee, which puts the device’s electrodes within contact of the peroneal nerve. The peroneal nerve is stimulated by FES during the swing phase of walking, which occurs when a person is about to swing their foot upward. The electrical stimulation allows the wearer to lift the front of their foot, preventing foot drop. When the foot returns to the ground, the electrical stimulation stops.
This pattern repeats over and over again while the individual walks. It may take some practice to get used to the timing with the device.
FES offers a sophisticated approach to alleviating foot drop. Although this treatment has led to significant improvements in people living with MS, it is important to be aware of both the pros and the cons of this technology.
The positive effects of FES include:
All of these benefits can translate to an increased quality of life for someone living with MS. Using an FES device can allow someone to accomplish daily-living activities, thanks to increased mobility.
Although FES has many associated benefits, the approach also has some drawbacks. A person using FES may experience skin irritation where the electrode contacts skin. They may also experience a tingling sensation on the skin and pain in the lower extremities while learning how to adjust to wearing the device as they walk.
Perhaps the most concerning drawback associated with FES therapy is the price. Unfortunately, insurance does not cover most FES therapy, and the cost of these devices typically ranges between $5,000 and $6,000. The National Multiple Sclerosis Society provides some financial resources for people living with MS.
There are several suppliers of FES-therapy devices. Two common FES systems include the ACP WalkAide and the Bioness L300 Go, both of which include small, battery-powered units that can be worn continuously to reduce impairment while walking. The L300 Go uses 3D motion detection while you take steps, analyzing your movement and delivering electrical stimulation as needed during your gait cycle. The WalkAide uses a built-in tilt sensor and accelerometer technology to stimulate the common peroneal nerve to help the wearer lift the foot at the right time as they step. ACP has also announced an upgraded version of the WalkAide, the WalkAide II, which is undergoing approval from the U.S. Food and Drug Administration.
If you are living with MS and experience foot drop, a neurologist or physical therapist can perform an evaluation to determine whether FES therapy is the right approach for you. If they think you are a good candidate for the therapy, they will usually perform a walk test with the device and provide instruction on how to use it.
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