 Following the location of optimal leads placement the participant will be rolled to the left lateral decubitus position right side up and the surgeon will proceed with the internalization of the implantable neurostimulator into the subcutaneous area of the abdomen. The wires of the implanted epidural electrodes will be tunneled under the skin and connected with the battery generator that will be placed in the abdominal area. If necessary, the same procedure will occur with the participant rolled to the right lateral decubitus position for the internalization of the second neurostimulator. 