Figures
(A) Example of a general cervical lordosis measurement (Cobb C2–C7 measurement). Single asterisk represents the angle (in degrees) used in analysis, with a higher value indicating increased lordosis between C2 and C7. (B) Example of an upper cervical lordosis measurement on a radiograph. Double asterisk represents the angle (in degrees) used in analysis, with a higher value indicating increased lordosis between C2 and C4.
Example of a C2 spinous process horizontal deviation measurement on a radiograph. The perpendicular distance (in millimeters) between the 2 lines represents the value used in analysis, with a higher value indicating increased C2 spinous process horizontal deviation.
Flow diagram of study participants. CGH=cervicogenic headache, CHISG=Cervicogenic Headache International Study Group.
Major criteria for cervicogenic headache diagnosis recommended by the Cervicogenic Headache International Study Groupa
a Major criteria as described by Sjaastad et al.24 Criterion II was not used in the current study.
Tables

Comparisons of Radiographic Postural Variables Between Participants With Cervicogenic Headache (CGH) and Age- and Sex-Matched Asymptomatic Individuals
a Data for general cervical lordosis required nonparametric tests: median and interquartile range reported and Wilcoxon rank sum used for comparison between groups.

Associations Between the Radiological Measurements of the Cervical Spinal Postural Variables and the Likelihood of Experiencing Cervicogenic Headache
a Statistical significance, P≤.05.
b Exact methods (SAS proc logistic) were used to obtain the 95% confidence interval (95% CI) for odds ratio, as the Wald statistic provided an interval (0.994, 1.18) for general cervical lordosis that was inconsistent with the significance indicated by the likelihood ratio test.