Improving Grasp Function in People With Sensorimotor Impairments by Combining Electrical Stimulation With a Robotic Hand Orthosis

Plain-language summary

Hand motor and sensory impairments resulting from neurological disorders or injuries affect more than 50 million individuals worldwide. Conditions such as stroke, spinal cord injury (SCI), and traumatic brain injury (TBI) can cause long-term hand impairments, greatly impacting daily activities and social integration. Since traditional physiotherapy has limited effectiveness in rehabilitation, assistive devices helping in performing in daily activities have emerged as a necessary solution. Soft exoskeletons offer advantages as they are more comfortable and adaptable for the user, but they often struggle to generate sufficient force. On the other hand, electrical stimulation garments, like e-sleeves, show promise by stimulating nerves and muscles in the forearm. However, achieving precise and stable movement control remains challenging due to difficulties in electrode placement for targeted stimulation. Furthermore, none of the currently available devices are capable of artificially restoring lost sensation in users' hands, limiting their ability to manipulate with fragile objects. Recognizing these limitations, our study proposes a solution that combines a standard hand soft exoskeleton with: (i) electrical stimulation to the fingers' flexor and extensor muscles to generate artificial muscle contractions synchronized with the exoskeleton motion, compensating for the lack of gripping force, and (ii) electrical stimulation to the nerves to artificially restore the lost sensation of touch, enabling users to receive feedback on the force they are applying when interacting with the environment. The investigators refer to this proposed combination as Sensible-Exo. To achieve this goal, our project aims to evaluate the functional improvements in assistive and rehabilitative scenarios using SensoExo in comparison to use only the exoskeleton or having no support at all. The exoskeleton will be coupled with an electrical stimulating sleeve capable of delivering non-invasive electrical stimulation in the form of Functional Electrical Stimulation (FES) and Transcutaneous Electrical Nerve Stimulation (TENS). A glove with embedded force and bending sensors will be used to modulate the electrical stimulation. Additionally, apart from studying the enhancement of functional tasks, the investigators will explore improvements in body perception, representation, and multi-sensory integration. Indeed, the investigators also aim at identifying the way patients perceive their body by means of ad-hoc virtual reality assessments that has been developed. Before each assessment patient will perform some predefined movement in virtual reality to familiarize with it and increase embodiment. During the study, participants will perform a range of tasks based on their residual abilities, including motor tasks (e.g., grab and release, Toronto Rehabilitation Institute Hand Function Test, grip force regulation test, virtual egg test), cognitive tasks (dual tasks), and assessments of body representation and perception. Some of these tasks will be conducted in Virtual Reality environments, both with and without active stimulation.

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