Hand Function for Tetraplegia

The purpose of this study is to evaluate the effectiveness of an implanted stimulator for providing hand function to individuals with cervical level spinal cord injury. The device stimulates the paralyzed muscles of the hand and forearm. The user of the device controls the stimulation by moving muscles that are not paralyzed, such as a wrist or neck muscle. The ability of the user to pick up and move objects, as well as perform various activities such as eating, drinking, and writing.

The overall object of this research is to provide restored functional abilities to individuals with cervical-level spinal cord injury through the use of an advanced wireless myoelectrically controlled battery-powered implanted neuroprosthetic system known as the "FIRSTHAND" System. This restored function can enable the individual to achieve greater independence in activities of daily living and an improved quality of life. Electrical stimulation of paralyzed muscles will be used to generate functional movements. The movements will be controlled using myoelectric signals generated from muscles under the subject's voluntary control. The specific hypotheses of this study are: 1) at least 75% of all subjects will be able to manipulate at least one more object in the Grasp-Release Test when using the advanced neuroprosthesis compared to without the neuroprosthesis. 2) At least 75% of all subjects will demonstrate an increased level of independence in at least one functional activity when using the advanced neuroprosthesis. 3) At least 75% of all subjects will demonstrate an average neuroprosthesis usage of at least three days/week.

Grasp and Release Test (GRT) - The Grasp and Release Test (GRT) [Wuolle, 1994; Smith et al., 1996; Carroll et al., 2000; Taylor et al., 2002; Mulcahey et al., 2004], developed at the Cleveland FES Center, has been utilized by multiple centers to show improvements in hand function after implantation of a neuroprosthesis and tendon transfers [Peckham, 2001]. This pick-and-place test requires the participant to unilaterally acquire, move, and release six objects varying in weight and size. The objects are: 1) a small peg, 2) a wooden cube, 3) a small juice can, 4) a videotape, 5) a paperweight (~1000g) and a simulated fork task (spring-loaded plunger). The number of objects that the participant can successfully manipulate are scored. Success in manipulating each object in the GRT is defined as the ability to pick up and place the object at least once within 30 seconds.

Inclusion Criteria: cervical level spinal cord injury; complete paralysis of fingers and thumbs; voluntary shoulder motion; electrically excitable forearm and hand musculature Exclusion Criteria: extreme contractures of the joints; skeletal immaturity; extensive denervation in the forearm and hand; poor surgical risk

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Kilgore KL, Bryden A, Keith MW, Hoyen HA, Hart RL, Nemunaitis GA, Peckham PH. Evolution of Neuroprosthetic Approaches to Restoration of Upper Extremity Function in Spinal Cord Injury. Top Spinal Cord Inj Rehabil. 2018 Summer;24(3):252-264. doi: 10.1310/sci2403-252.

Kilgore KL, Hoyen HA, Bryden AM, Hart RL, Keith MW, Peckham PH. An implanted upper-extremity neuroprosthesis using myoelectric control. J Hand Surg Am. 2008 Apr;33(4):539-50. doi: 10.1016/j.jhsa.2008.01.007.