A neuroprosthesis for high tetraplegia

Background: This case report describes a neuroprosthesis that restored shoulder and elbow function in a 23-year-old man with chronic C3 complete tetraplegia. Before implementation of the neuroprosthesis, electrodiagnostic testing revealed denervation from C5 to T1, with the greatest degree of denervation in the C8 and T1 myotomes. Thirteen percutaneous intramuscular electrodes were implanted into muscles acting on the shoulder and elbow of one upper limb. Before functional testing, the subject underwent a conditioning regimen to maximize the strength and endurance of the implanted muscles. Results: After completion of the 8-week exercise regimen, stimulated active range of motion against gravity included 60° of shoulder abduction, 45° of shoulder flexion, 10° of shoulder external rotation with the shoulder passively abducted to 90°, and 110° of elbow flexion. Stimulated elbow extension lacked 20° of full extension with gravity eliminated. After system setup, the subject was able to pick up mashed potatoes on a plate with a utensil and bring them to his mouth using the neuroprosthesis and a balanced forearm orthosis. A switch mounted on the headrest of the subject's wheelchair and a position sensor mounted on the contralateral shoulder allowed the subject to control movement of his upper limb.