Clinical features, risk factors, and a nomogram for predicting refractory cervicogenic headache: a retrospective multivariate analysis - Li, Jiawei; Wu, Baishan; Wang, Xiaochen; Zhao, Lijuan; Cui, Jie; Liu, Jing; Guo, Kaikai; Zhang, Xiaoyu; Liu, Juan (Frontiers in Neurology, 2025)