Beneficial Effect of Tizanidine on the Ischemic Muscle Contraction in Chronic Muscle Contraction Headache.

Sakuta M , Sakuta Y Drooping head syndrome; Significance of posture and neck instability as a cause of muscle contraction headache. Cephalgia 1989, 9(suppl.10): 119–120

Ad Hoc Committee on classification of headache of the national institute of neurological diseases and blindness: Classification of headache.