Yet another study has found that chiropractic care helps headache sufferers: Spinal manipulation seems to have a significant positive effect in reducing hours with headache and intensity of headache and analgesic consumption in cases of cervicogenic headache.

Nilsson N, Christensen HW, Hartvigsen J. “The Effect of Spinal Manipulation in the Treatment of Cervicogenic Headache.” Journal of Manipulative and Physiological Therapeautics, Volume 20, Number 5, June 1998, Pages 326-330.