Patients presenting with occipital pain underwent diagnostic blocks of their lateral atlanto-axial joints if they demonstrated clinical features presumptively suggestive of a C1-2 origin for their pain. Of 34 patients investigated, 21 obtained complete relief of their headache following diagnostic blocks, indicating that a C1-2 source of occipital pain is not rare. The clinical features used to select patients for blocks, however, had a positive predictive value of only 60%. Further study of headaches from C1-2 seems justified in order to establish more definitively the prevalence of this condition and how it might become better recognized in practice.
Aprill C, Axinn MJ, Bogduk N. Cephalalgia. 2002 (Feb); 22 (1): 15-22