Engagement-sensitive interactive neuromuscular electrical therapy system for post-stroke balance rehabilitation - a concept study

Stroke is caused when an artery carrying blood from heart to an area in the brain bursts or a clot obstructs the blood flow thereby preventing delivery of oxygen and nutrients. About half of the stroke survivors are left with some degree of disability. Neuroplasticity is involved in post-stroke functional disturbances, but also in rehabilitation. Beneficial neuroplastic changes may be facilitated with neuromuscular electrical stimulation (NMES) where active cortical participation in rehabilitation procedures may be facilitated by driving NMES with electromyogram (EMG), electrooculogram (EOG), and electroencephalogram (EEG) derived biopotentials, that represent simultaneous volitional effort and task engagement. During the visuomotor standing balance task, we propose that gaze-interaction (e.g., fixation duration, pupil diameter, blink rate) with the visual stimuli can be a measure of task engagement which can be used to adapt task difficulty to facilitate post-stroke residual visuomotor function. Here, the elapsed time between the last visual fixation to the target and the initiation of the motor response, known as the quiet eye (QE) period, has emerged as a characteristic of higher levels of performance. In this article, we discuss this novel interactive therapy paradigm consisting of a low-cost static posturography system combined with engagement-sensitive volitionally driven NMES for post-stroke balance rehabilitation.