By definition, a cervicogenic headache is one which is caused by a disorder within the cervical spine or soft tissue of the neck.  It is a secondary headache caused by another illness or physical issue, including poor posture, stress on the muscles, current or prior injuries, disc problems, problems sleeping, and fatigue. The pain usually occurs on one side of the head or face and can be easily aggravated by sudden movements or certain postures.
People with cervicogenic headaches often have reduced range of motion in the neck. The pain may radiate from the neck or back of the head to the front of the head or behind the eye. It is important to check with a primary provider to exclude the possibility of other causes of the headaches and to determine the best course of action.
Manual therapy and exercise therapy are viable treatment options for cervicogenic headache sufferers. Results of one study show that these types of therapy can reduce the frequency, intensity, and duration of cervicogenic headaches after six weeks of treatment.  Not only that, but results were maintained at three, six, and 12 month follow-ups.
What is Cervicogenic Headache? [Internet] Available from: https://americanmigrainefoundation.org/resource-library/cervicogenic-headache/
 The International Classification of Headache Disorders, 2nd Edition. Cephalalgia: An International Journal of Headache, 2004: 24 (1).
 Jull G, Trott P, Potter H, et al. A randomized controlled trial of exercise and manipulative therapy for cervicogenic headache. Spine, 2002; 27 (17): 1835-1843.