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Implanted Nerve Electrical Stimulation allows to Selectively Restore Hand and Forearm Movements in Patients with a Complete Tetraplegia

Background Functional Electrical Stimulation (FES) is used for decades in rehabilitation centers. For patients with a spinal cord injury (SCI), FES can prevent muscular atrophy, reduce spasticity and/or restore limb movements. To this last aim, FES external devices can be used, but elicit imprecise movements. FES implanted devices used neuromuscular stimulation and required implantation of one electrode for each site (muscle) to stimulate, an heavy surgical procedure and 10 times more electrical charges than nerve stimulation. Moreover, complications related to the numerous implanted components could appear over time. The purpose of this work is to evaluate whether a multi-contact nerve cuff electrode can selectively activate forearm and hand muscles and restore functional movements in patient with a complete tetraplegia. Methods A 12-contacts cuff electrode was designed to selectively activate, without damage it, multi fascicular peripheral nerve (1). Six subjects rwith at least one extensor or one flexor muscle stimulable by surface electrical stimulation, have been enrolled into the study. During the surgical procedure, radial or median nerve was stimulated through up to 35 different configurations of stimulation at an intensity up to 2.1 mA (25 Hz, pulse width 250 µs, inter-pulse 100 µs). Surface electrodes were positioned upon the forearm to record compound muscle action potentials elicited by nerve electrical stimulation. Recruitments curves and videos were recorded. Results The multicontact cuff electrode allowed us to selectively activate group of muscles to produce multiple, independent and functional hand and forearm movements in persons with tetraplegia. A surface electrical stimulation did not allow all those movements.