Idiopathic spinal cord herniation in patients with ankylosing spondylitis: a dual-center case series of 7 patients.

Idiopathic spinal cord herniation (ISCH) is a rare disease characterized by the protrusion of the spinal cord through a dural defect. The underlying mechanisms of this pathology remain poorly understood, and its co-occurrence with ankylosing spondylitis (AS) has rarely been addressed in the existing literature. The aim of this case series was to describe the shared clinical and imaging characteristics of patients diagnosed with AS and ISCH and to evaluate the feasibility and prognosis of surgical treatment. We retrospectively reviewed 7 patients treated for AS and ISCH at Peking University First Hospital and Beijing Unicare Hospital from January 2022 to December 2024. Demographics, surgical procedures, preoperative and postoperative clinical and imaging manifestations, as well as complications were analyzed. Chronic bone destruction and prolonged spinal kyphosis were common features observed in our case series. All patients underwent pedicle subtraction osteotomy (PSO), and the postoperative outcomes demonstrated significant spinal correction and an enhanced quality of life. No postoperative complications were observed, and neurological function remained stable during the follow-up study. The PSO surgery performed without addressing the herniated spinal cord can still achieve favorable spinal corrective effects and improve the patient's quality of life without increasing the risk of neurological damage.