Cervicogenic headache: diagnostic criteria.

Criteria for the diagnosis of cervicogenic headache are proposed, which include unilateral head pain, symptoms and signs of neck involvement, non-clustering episodic moderate pain originating in the neck then spreading to the head, and response to root or nerve blockade; plus rarer and non-obligatory features such as autonomic disturbances, dizziness, phonophotophobia, monocular visual blurring, and difficulty swallowing.