Functional electrical stimulation for foot drop in multiple sclerosis. Patient selection

Functional electrical stimulation (FES) to restore movement in paralysed or weak individuals has long been regarded as feasible for a number of conditions. As each decade brings new innovations in electronics and microprocessing, better and more controlled systems become possible. Here, the evaluation of movement problems in multiple sclerosis (MS) and identification of suitable subjects through the application of a set of selection criteria is outlined. The application of FES for foot drop has been considered. Selection of people with MS and footdrop for FES was initially made with particular reference to level of mobility, range of ankle joint movement and safety (good balance). It was felt that both walking speed and distance were important criteria since inability to walk 50 m indicates seriously limited mobility in MS. One subject who conformed to the walking speed and distance criteria initially subsequently developed slower more laboured walking. When this occurred she found that she was no longer able to use the device. It appears that there is a limit to successful use of the device in terms of walking ability. However, it is not clear yet what other gait factors are the most important influence on the successful application of FES for footdrop. Walking ability and the other selection criteria relating to stiffness of the limb and range of movement all appear to have yielded suitable candidates for FES