1. Department of Interventional and Surgical Pain Management, Cincinnati Veterans Affairs Medical Center , Cincinnati, OH 45220, United States
2. Department of Neurosurgery, University of Alabama at Birmingham , Birmingham, AL 35294, United States
3. Department of Neurology, Mayo Clinic , Rochester, MN 55905, United States
4. Center for Sleep Medicine, Pulmonary and Critical Care Medicine Division, Department of Internal Medicine, Mayo Clinic , Rochester, MN 55905, United States