Isthmic spondylolisthesis combined with schwannoma occurring at the same vertebral level: a case report and literature review

Background: The occurrence of schwannomas at the level of isthmic spondylolisthesis has not yet been reported. Preoperative identification of the responsible lesion and a rational surgical plan are essential for successful surgery. Case presentation: We report the case of a 56-year-old woman who presented with a six-year history of low back pain and a three-year history of radiating pain in the left lower extremity. Physical examination revealed signs of left L5 root compression. Computed tomography revealed left L5-S1 intervertebral foramen stenosis with an isthmic fracture. Unexpectedly, magnetic resonance imaging (MRI) showed an abnormal 12 mm*11 mm*21 mm intradural mass with inhomogeneous contrast enhancement at the level of the spondylolisthesis. Isthmic spondylolisthesis and schwannoma were suspected. Based on the imaging and physical findings, we inferred that the lower-extremity pain was primarily caused by lumbar spondylolisthesis. Under general anesthesia, the patient underwent posterior lumbar interbody fusion of L5-S1 and intradural total tumorectomy. Histopathological examination of the surgical specimen revealed a schwannoma. The patient's symptoms resolved postoperatively, and intervertebral fusion was satisfactory at the 12-month follow-up. Conclusion: This case demonstrates the difficulty of determining the responsible lesion, highlighting the importance of meticulous clinical and imaging examinations. Determining the responsible lesion is crucial for diagnosis and treatment.