Predictors of Response to Occipital Nerve Stimulation in Patients with Refractory Chronic Cluster Headache: Protocol for a Prospective Observational Study. - Portocarrero-Sánchez, Leonardo; Gil-Martínez, Alfonso; Paz-Solís, José Francisco; Román-Aragón, María; Mansilla-Fernández, Beatriz; Elizagaray-García, Ignacio; Rizea, Cristian; Marín-Esteban, Saúl; Utrilla, Cristina; de-Toro-Cañizares, Celia María; Zaballa-Pérez, Lucía; Gallego-Ruiz, Rebeca; et al. (Brain Sciences (2076-3425), 2026)