Alteration of neural geometry for selective nerve stimulation

Previous work has demonstrated the ability of a peripheral nerve electrode to slowly reshape a nerve. Those electrodes, however, were designed to penetrate within the epineurium of the nerve, raising questions regarding their safety. The authors now show that penetration of the epineurium is not necessary. Instead, the electrode is designed to increase the surface area of the nerve. In particular, the authors present results from a electrode that reshapes the nerve into a flattened rectangle. In four acute trials, the electrode was placed on the cat sciatic nerve for 24 hours. After 24 hours, the nerve cross-section was rectangular and the nerve surface area was 23% larger than that of a cylinder. The surface area of the largest fascicle was 10% greater than the surface area of a cylinder. Stimulation results show that the electrode selectively produced the major functions of the cat ankle with single channel stimulation. Simultaneous stimulation from two channels produce recruitment not possible with single channel alone, and was able to produce recruitment in nearly all of moment space