Combining BCI with functional electrical stimulation for facial nerve paralysis in locked-in indviduals

Abstract

Locked-in syndrome (LIS) is a nervous system disorder that is characterised by loss of voluntary muscle control, which can lead to whole body paralysis. Classical and incomplete LIS patients retain the ability to produce eye movements, which enable communication through gaze-controlled/eye-tracking systems that allow patients to choose letters from a keyboard to type messages on a screen. However, these communication methods limit rapid, natural communication and are unable to allow the expression of emotion. Furthermore, total LIS patients do not retain the ability to produce eye movements, and as such, gaze-controlled communication systems are inaccessible to these patients. To overcome the limitations of such communication systems, this paper posits that the combination of intracortical brain computer interfaces (iBCI) and functional electrical stimulation (FES) technology could be utilised to restore functional facial movements and facial expressions in locked-in individuals. Previous research has demonstrated the restoration of functional arm and hand movements in tetraplegic patients using iBCI-FES systems. Furthermore, facial FES research has shown that FES-induced functional facial movements and facial expressions are feasible in healthy subjects and facial nerve paralysis patients (FNP). This line of research has successfully demonstrated FES-induced eyeblinks, eyebrow raises, frowning, smiling, and limited speech articulation. However, no research to date has attempted to induce functional facial movements or facial expressions using FES on LIS patients. This paper argues that facial FES research findings in FNP patients can be used to inspire novel iBCI-FES systems for LIS patients to restore facial movements and facial expressions. Such systems could be used to improve communication and expression of emotions in these patients, which would likely have positive effects for their wellbeing and QoL.