1. Department of Neurology, Barrow Neurological Institute St. Joseph's Hospital and Medical Center Phoenix Arizona USA
2. Department of Anesthesiology, Intensive Care, and Pain Management Ain Shams University Faculty of Medicine Cairo Egypt
3. The Louis Calder Memorial Library University of Miami Miller School of Medicine Miami Florida USA
4. Division of Headache, Department of Neurology University of Miami Miller School of Medicine Miami Florida USA
5. Department of Neurology & Neurological Sciences Stanford Health Care Stanford California USA
6. Department of Anesthesiology, Perioperative and Pain Medicine Stanford Health Care Stanford California USA