For stroke survivors with persistent foot drop, the challenges of walking safely and efficiently are immense. While surface Functional Electrical Stimulation (FES) has been used for years, recent research highlights the significant advantages of implanted FES systems in improving mobility and quality of life.
Instead of using skin-surface electrodes, implanted FES involves a neurostimulator placed under the skin to directly stimulate the peroneal nerve, which controls the muscles responsible for lifting the foot. This offers a more precise and consistent stimulation, and is controlled wirelessly via a foot sensor or other external trigger.
A recent study compared the ActiGait® implanted system to traditional ankle-foot orthoses (AFOs) in stroke survivors. The findings were compelling: participants showed significantly higher success rates (Δ4.7%) in avoiding unexpected obstacles on a treadmill with the implanted FES. This benefit was even more pronounced for those with greater motor impairment. The unrestricted ankle mobility with FES is key for navigating real-world, uneven terrain.
While some systematic reviews found surface FES and AFOs to be equivalent in improving walking speed, the superior gait adaptability with implanted FES is a key differentiator. This means a more natural and less compensatory walking pattern.
By providing consistent electrical stimulation, implanted FES facilitates more efficient and repetitive muscle contractions. This intensive, task-specific practice is crucial for promoting neuroplasticity—the brain’s ability to rewire neural connections—which can lead to a therapeutic “carry-over” effect even when the stimulator is turned off. Research shows that survivors using implanted FES show an equivalent walking Speed to those using AFOs, with better gait adaptability. Survivors also often prefer FES over AFOs, citing greater comfort, improved cosmesis (appearance), and the ability to wear a wider range of footwear.
Implanted FES is a consideration for individuals with moderate to severe drop foot caused by an upper motor neuron lesion, such as from a stroke, who have a well-preserved peroneal nerve and sufficient cognitive function to manage the system.
