Clinical Safety and Efficacy of Infrared Neural Stimulation During Nerve Transfers

Many surgical procedures such as brachial plexus reconstruction, nerve repair, and dorsal root rhizotomies rely on the spatial selectivity of their neural stimulation methods to identify specific nerve fascicles or rootlets. Due to the variable distribution of nerves between patients, many times it is not enough to rely on the historical topography of nerves to determine their location and identity.Currently, electrical stimulation (ES) methods are used to stimulate nerves in order to locate and map them intraoperatively. ES, however, is subject to current spread in which the electrical stimulus extends beyond the area proximal to the electrode into the surrounding tissue. This can result in the stimulation of multiple fascicles introducing ambiguity as to the location and/or identity of a specific nerve or fascicle. Our group has shown that infrared neural stimulation (INS), a novel optical and label-free means of exciting neural tissue, is capable of safely stimulating nerves with a higher degree of spatial specificity than traditional ES methods. Our clinical studies have even shown that INS can outperform ES, achieving isolated rootlet responses. The investigators hypothesize that the spatial selectivity of INS can be further utilized in upper extremity surgeries such as brachial plexus reconstruction and nerve transfers to improve intraoperative nerve identification and localization. While the initial clinical work was performed with a costly clinical laser system, our group has demonstrated the efficacy of cost-effective laser diode systems for INS in animal models in vivo.The safety of these lasers, however, has yet to be proven histologically in human patients. The objective of this proposal is two-fold: to demonstrate the efficacy of INS for spatially selective nerve stimulation in the upper extremity and to determine the histological safety of INS using diode laser systems in human patients. To do so, the investigators will recruit patients undergoing brac