Misperception of visual verticality in patients with primary headache disorders: a systematic review with meta-analysis - Obrero-Gaitán, E; Manrique-Navarro, M; Lérida-Ortega, M A; Rodríguez-Almagro, D; Osuna-Pérez, M C; Lomas-Vega, R (Brain Sci, 2020)