1 Orthopedic Surgery, University of Maryland School of Medicine, Baltimore, Maryland, USA.
2 Professor of Anesthesiology, Neurology, Physical Medicine & Rehabilitation and Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland, USA steven.cohen@northwestern.edu.
3 Professor of Anesthesiology, Neurology, Physical Medicine & Rehabilitation, Psychiatry and Neurosurgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
4 Professor of Physical Medicine & Rehabilitation and Anesthesiology, Walter Reed National Military Medical Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.