Objective: This study aimed to explore the related risk factors in patients who underwent hemilaminectomy for lumbar spinal schwannoma resection and who experienced deterioration of postoperative lower back pain in comparison to preoperative pain levels.
Methods: This retrospective study recruited 61 patients from the First Affiliated Hospital of An Hui Medical University between January 2018 and June 2019. All data were collected from clinical records and analyzed at 1-month and at 1-year follow-up. The visual analog scale (VAS) was used to evaluate pain, and neurologic function was assessed using the Modified McCormick Scale. Intraoperative neurophysiological monitoring was used to assess neuronal integrity and mitigate injury. Statistical analysis of the data was performed using the SPSS version 19 software.
Results: Preoperative pain improved dramatically in the 1-year follow-up (VAS: preoperative, 3.84± 2.19; 1-year follow-up, 2.13± 2.26; P< 0.001). The pain-improved group and worsened group showed a significant difference at 1-month (VAS: 1.76± 1.56; 5.54± 1.26; P< 0.05) and at 1-year (VAS: 0.83± 1.09; 4.80± 1.58; P< 0.05) follow-up. The pain-improved and worsened groups had a significant difference in tumor size and hemilaminectomy removal segments at 1-month and 1-year follow-up, but A-train occurrence on electromyography could only be seen as a statistical difference in the 1-month follow-up. Logistic regression analysis revealed that tumor size was an independent risk factor for postoperative lower back pain deterioration.
Conclusion: The hemilaminectomy approach is a safe and effective method that can dramatically relieve pain in spinal lumbar schwannoma resection. Tumor size is an independent risk factor for postoperative lower back pain. A-train on spontaneous electromyography has been shown to be a reliable predictive factor for the evaluation of postoperative lower back pain. However, further detailed analysis of A-train characteristics can provide a more accurate warning during surgery.
Keywords: lumbar spinal schwannoma, lower back pain, hemilaminectomy, electromyography, intraoperative monitoring