1 Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany.
2 Department of Clinical Medicine, Danish Pain Research Center, Aarhus University, Aarhus, Denmark.
3 Indiana Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery and Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN, USA.