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Abstract
Targeted reinnervation (TR) is a novel, revolutionary strategy to achieve a functioning neural-machine interface that allows upper extremity amputees to voluntarily control motorized prosthetic arms just as they would control their native arms. Developed and pioneered by Todd Kuiken and Gregory Dumanian at Northwestern University, TR employs a process called neurotization, in which the stumps of amputated nerves of the brachial plexus (that had originally innervated the arm) are connected to denervated, otherwise functionless, remnant muscles in the shoulder, chest, and/or proximal arm. After several months, the newly reinnervated muscle segments act as biological amplifiers of the nerve action potentials that had previously controlled the arm. For example, if the radial nerve is connected to one portion of the pectoralis major and the musculocutaneous nerve is connected to pectoralis minor, then when the patient "thinks" to extend his/her elbow, the pectoralis major muscle will contract. Likewise, when the patient "thinks" to flex his/her elbow, the pectoralis minor will contract. The EMG Signals of these reinnervated muscle segments are then detected by electrodes placed on the skin and can be used to control myoelectric prostheses in an intuitive way that requires less training compared to conventional prostheses to achieve greater degrees of freedom. 1 So far TR has been successfully implemented in nine human subjects. Since the beginning of the war in Iraq, with many US soldiers returning stateside after suffering from blast amputations, the US Government has placed more of a focus on the treatment of amputations through the Defense Advanced Research Projects Agency (DARPA) of the Department of Defense (DoD). There is now a more visible, everyday need to improve upon the management of human amputees. One problem often experienced by people who have suffered from amputations or other forms of trauma is the formation of painful neuromas that are responsible for various uncomfortable sensory disturbances.6 We hypothesize that TR can also be an effective technique for the prevention and treatment of painful neuromas, which is supported empirically by the fact that none of the ten patients in our series who have undergone TR has developed a painful neuroma, and TR has even eliminated pre-existing painful neuromas in several of these patients. Animal studies will help provide a better understanding of neuroma formation in the setting of TR. My overall goal for my upcoming research year is to help refine strategies for Targeted Reinnervation and to investigate the utility of TR as a way to prevent or treat neuroma formation.