Speaker: Ben Christensen. Advisor: Patrick Tresco, Ph.D.

Abstract:

Peripheral nerve electrodes have been used clinically for decades to stimulate areas of lost function. The electrodes traditionally used have been of a cuff design, which does not necessitate a penetrating injury into the nerve. However, histological studies have shown evidence of morphometric changes in the underlying nerve following nerve cuff electrode implantation, suggesting that the presence of a foreign-body around a nerve in the absence of a penetrating injury could create an inflammatory response sufficient to alter the underlying nerve structure. Additionally, we have observed in previous studies that activated macrophages are present at the material interface of silicone cuffs. A further understanding of this inflammatory reaction would be important not only for nerve cuff electrodes, but for more selective penetrating electrodes which use nerve cuffs to hold the penetrating arrays in place. Also of importance is finding ways to mitigate this inflammatory reaction. We hypothesize that the presence of a silicone nerve cuff is sufficient to cause a persistent inflammatory reaction and lead to changes in underlying nerve structure and that the inflammatory reaction and morphometric changes can be ameliorated by using a open mesh cuff as opposed to a traditional solid cuff. Also of importance in the field of peripheral nerve electrodes is the development of electrodes which offer higher specificity than that available with the use of nerve cuff electrodes. Axially penetrating arrays offer such potential, but the histological description of the nerve following implantation of such arrays is limited. We hypothesize that the implantation of such arrays will lead to alterations in nerve composition that are more significant than those seen with cuffs alone. To test our hypothesis, we plan a series of experiments using the rat sciatic nerve as a model. Outcomes will be evaluated using immunohistochemistry and quantitative morphometric data collection techniques.