Failed back syndrome or extra-spinal sciatica? Ischiofemoral syndrome as a cause of persistent radicular pain after 4 lumbar spine surgeries. - Barriga-Martín A; Paredes-Muñóz O; Peral-Alarma M; Romero-Muñóz LM; Guimbard-Pérez JH (Neurocirugia, 2026)