Functional Electrical Stimulation (FES)
The National MS Society frequently fields questions about functional electrical stimulation (FES) — usually in relation to the products WalkAide from Innovative Neurotronics, NESS L300™ from Bioness® and the Odstock Dropped Foot Stimulator from Odstock Medical Limited in the United Kingdom.
Functional electrical stimulation (FES) is a treatment that involves the application of a mild electrical stimulus to a muscle that helps it to move better. Sometimes, due to nerve damage from conditions such as MS, the muscle no longer receives the correct message from the central nervous system. FES provides an external signal that makes the muscle move.
Some people with MS have difficulty lifting their foot (foot drop) while walking and are at risk to trip and fall. Most MS rehabilitation specialists recommend physical therapy to improve strength and address any stiffness; and, if needed, an ankle foot orthosis (AFO) to manage foot drop. The brace, which is usually made of plastic, is worn around the lower leg and foot. Most AFO’s hold the ankle and foot in a fixed position, but some devices have a hinge that allows movement of the ankle.
Two devices — the WalkAide and NESS L300 — can help alleviate foot drop. They work by sending low-level electrical impulses to the peroneal (sometimes called fibular) nerve, which signals leg muscles to lift the foot. These devices are relatively small, battery powered, and usually worn continuously while someone is up and about. Seen as easier to wear and more convenient than an AFO by many users, they are also a great deal more expensive — about $5,000-$6,000 — and typically not covered by insurance.
A number of studies of FES devices in MS have demonstrated improvement in walking speed in short distance walking tests. However, FES devices will not help everyone with lower extremity weakness or foot drop. It is important to be evaluated by a rehabilitation specialist with experience in MS to determine the correct management plan – including the correct assistive device.