Spinal arachnoiditis may present with low back pain, foot pain, loss of sensation and motor weakness. In addition, some people may have syringomyelia due to impaired flow of cerebrospinal fluid. In the etiology, there are infections, intrathecal steroid or anesthetic injection, trauma, subarachnoid hemorrhage, myelographic contrast media, multiple spinal surgery and lumbar puncture history. The patient’s past treatment history, clinical and MRI examination are important in diagnosis. In this case, we aimed to discuss postoperative adhesive arachnoiditis which caused low back pain, and imaging findings in the light of literature. Key words: Adhesive arachnoiditis; Cauda equina; Pain; Anesthesia; Surgery; Imaging; MRI Citation: Kara T, Davulcu O, Ates F, Arslan FZ, Sara HI, Akin A. What happened to cauda equina fibers? Adhesive arachnoiditis. Anaesth. pain intensive care 2020;24(5): Received: 29 April 2020, Reviewed: 17 June 2020, Accepted: 18 June 2020