Earl Merson is researching the use of Functional Electrical Stimulation (FES) to improve the walking of people with drop foot caused by central neurological damage.

Drop foot is a medical condition where people cannot lift one or both feet when walking, causing them to trip. It is often a result of a stroke or multiple sclerosis. Electrical stimulation of the common peroneal nerve (by the knee) is recognised by NICE as an effective treatment. The most common method of application is with a pair of self-adhesive electrodes (avoiding the need for surgery). In most cases, the electrodes must be placed carefully to achieve the desired foot movement. Many people find this difficult, through lack of dexterity or limited understanding of how to adjust the electrodes for best effect.

Earl is investigating the potential for using two channels of stimulation to control the foot response, aiming for strong foot lift (to reduce tripping) while maintaining ankle stability during loading and comfort. The relative...

strength of the two channels could be controlled manually or automatically, using feedback from an in-shoe sensor. This approach differs from other multi-electrode transcutaneous systems, which attempt to position a single channel in the optimum location for balanced nerve recruitment. Using two channels is physically and electrically less complex than multi-electrode arrays.

This project is a feasibility study, investigating the physiological and functional effects of two-channel stimulation, from direction and consistency of foot movement to ease of setup and walking ability.

The project is funded by Odstock Medical Limited and a BU studentship. Earl's background is in electronic engineering, recently applying this to biomedical applications. He has a weekly half-day clinic at the National Clinical FES Centre at Salisbury District Hospital, where he reviews the progress of FES users and assists them in getting optimum benefit from the treatment.