Isthmic spondylolisthesis combined with schwannoma occurring at the same vertebral level: a case report and literature review - Niu, Renrui; Zhao, Jianhui; Li, Chaoyuan; Guo, Fengshuo; Duan, Yuchi; Luo, Wenqi; Gu, Rui (Frontiers in Surgery, 2025)