Headache Disorders, Secondary

• Northwestern Health Sciences University — Bloomington, Minnesota, United States
• University of Western States — Portland, Oregon, United States

• Montefiore Medical Center — The Bronx, New York, United States

• Derince Research and Training Hospital — Kocaeli, Turkey (Türkiye)

• Alabama Physical Therapy & Acupuncture — Montgomery, Alabama, United States

• University Hospital Leicester — Leicester, United Kingdom

• University of Social Welfare and Rehabilitation Sciences — Tehran, Islamic Republic of, Iran

• Dept. of Neurology and Clinical Neurophysiology, Norwegian Headache Centre — Trondheim, Norway

Not specified

• Suzhou municipal hospital — Suzhou, Anhui, China
• the second hospital of Hebei medcial university — Shijiazhuang, Hebei, China
• Henan Province Hospital of Traditional Chinese Medicine — Zhengzhou, Henan, China
• Jinzhou central hospital — Jinzhou, Liaoning, China

• Montreal Neurological Hospital and Institute — Montreal, Quebec, Canada