A New Distributed Neuroprosthesis Enables Hand Grasp and Trunk Posture after Cervical Spinal Cord Injury
1Kilgore K, 1Hoyen H, 1Keith M, 2Triolo R, 3Bryden A, 2Lombardo L, 2Hart R, 2Miller M, 1Nemunaitis G, 3Peckham P
1MetroHealth Medical Center, Cleveland, OH, United states; 2Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, OH, USA; 3Case Western Reserve University, Cleveland, OH, USA
Objective: Provide significantly increased functional ability and independence for individuals with cervical level spinal cord through the implantation of a modular networked neuroprosthesis that provides hand grasp opening and closing, overhead reaching, and trunk stability.
Design/Methods: We have developed an implantable network of modules, the “networked neuroprosthesis” (NNP), which is capable of stimulating paralyzed muscles throughout the body and recording myoelectric signals from muscles under voluntary control. Coordinated stimulation patterns can be programmed into the NNP to create functional movements on command. Using this system, we can provide motor complete cervical SCI individuals with grasp opening and closing, overhead reach, and trunk stability. The system also includes continuous temperature monitoring and 3-axis accelerometer data to record torso and upper extremity motion. The NNP system is implanted in a one- or two-stage surgical procedure. The recipient undergoes a three week period of decreased mobilization and then four weeks of muscle conditioning prior to initiating functional training and evaluation.
Results: The NNP System has now been implanted in three individuals with SCI to date. The implementation of the NNP with each individual is customized to their retained function, but generally involves placement of 20-24 stimulating electrodes in the trunk and one upper extremity. Control is provided by 1-2 myoelectric signal recording electrodes in voluntary muscles in the forearm, shoulder, and neck. The implanted power module is placed in the abdomen. The results have been positive, and all subjects have demonstrated improved functional use of their hand and trunk. Demonstrated activities include eating with a fork, writing, and getting items out of the refrigerator. We now have over one year follow-up with the first recipient. Adverse events have been limited but include the removal of one component of the system for the first subject due to a localized infection. Evaluation of all three subjects, as well as implantation of additional subjects, is ongoing.
Conclusion: The NNP is the first modular neuroprosthesis designed to provide multiple coordinated functions for individuals with SCI. This system provides increased functional ability of the hand, arm, and trunk. The system is fully implanted (no external components), freeing the user in their activities. The ability to customize the muscles targeted for stimulation and for myoelectric control is a significant advantage of the modular NNP concept.
Support: This work is supported by NIBIB (R01-EB-001740), NINDS (U01-NS-069517); VA RR&D (A1804R, B4853C, B6406R, and A6027R); DOD (SC090230 and SC130252); FDA Orphan Products (R01-FD-005409); The Paralyzed Veterans of America (Grant #2816); and the Craig H. Neilsen Foundation (#164569).
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