Treating Foot Drop in People With Multiple Sclerosis Using Electrical Stimulation

Due to damage of their central nervous system, people with multiple sclerosis (MS) often develop abnormal gait. One common problem is the inability to lift the foot during the swing phase; this is called foot drop, and is caused by loss of ankle dorsiflexor strength and spasticity of the ankle plantarflexors. Foot drop leads to imbalance and increased risk of falling, due to the foot dragging on the ground. Treating foot drop can result in improved gait, faster walking speeds, improved balance and reduced risk of falling. Functional electrical stimulation (FES) stimulates either the superficial or deep branches of the common peroneal nerve. This stimulation leads to contraction of the ankle dorsiflexors and evertors, which causes dorsiflexion and eversion of the foot, resulting in the stepping motion of lifting the toes toward the shin. This reduces foot drop, allowing the user to regain a more natural stepping pattern; it also reduces spasticity, strengthens muscles and increases joint range of motion. The Bioness L300 Foot Drop System consists of three components: a leg cuff worn just below the knee, which provides electrical stimulation to the common peroneal nerve; a gait sensor attached to the shoe, which detects which stage of the gait cycle the foot is in; and a control unit, which is used to adjust the level of stimulation received. These three components communicate wirelessly with each other, so that the electrical stimulation is applied at the appropriate time during each gait cycle. The study physician will set up the system to optimize stimulation according to each participant's gait and needs, and participants will use the system for 12 weeks. There will be an initial four week adaptation period for using the system. During this first four weeks participants will gradually increase their use of the system until they are using it all day, which will allow their muscles to adjust to the electrical stimulation and help prevent fatigue. During the remaining eight weeks participants will be instructed to use the system all day, when walking at home and in the community. Participants will have their walking speed and heart rate measured during a 10-metre straight line walking test and a 4-minute figure-8 walking test at baseline, weeks 4, 8 and 12. Participants will perform both tests at each time point without and with the L300 Foot Drop System. Participant satisfaction will be assessed at the end of the 12-week trial.