Functional electrical stimulation during post stroke walk: Latest developments

After stroke some residual gait deficits can remain and are prevalent. Foot drop is one of the common impairment which affects around 20% of stroke survivors. This impairment is caused by a paresis (total or partial) of the muscles involved in ankle dorsiflexion. This muscle weakness makes the ground clearance problematic during the swing phase of gait. This default can be compensated by ankle foot orthosis (AFO) but also by functional electrical stimulation. This is an ancient technique that has benefited from recent advances in technology: wireless link, implanted stimulation, replacement of the heel switch by an inclinometer (System Walkaid)… The SEF is effective in improving walking parameters including walk speed but despite these recent technological improvements, it does not show that it is a more effective device than ankle foot orthoses in a recent study [1]. An inertial node combining an accelerometer, a gyroscope and a magnetometer placed on one of the two legs, is used to estimate the continuous walking cycle [2]. This can advantageously replace the switch in the heel to improve reliability to determine when to start or end the stimulation and also allow for example to start the stimulation at any time, including before the heel off the ground. Moreover, this inertial node should also estimate a number of walking parameters including the quality of ankle dorsiflexion and walking type (normal walk but also pass an obstacle, turn around or climbing stairs) and thus to propose an adaptive functional electrical stimulation in an intelligent way. The purpose of the presentation is to provide an update on the latest clinical studies and develop perspectives brought by the use of inertial nodes coupled with a wireless stimulator to integrate decision algorithms