Utility of intraoperative neuromonitoring in surgery for spinal cord tumors

Objectives: The use of intraoperative neuromonitoring (IONM) in spinal surgery, particularly for spinal cord tumors, has gained prominence despite the debate on its therapeutic advantages. Although its routine use is often advocated, its utility in spinal cord tumor surgeries remains underexplored, especially concerning post-operative deficits. This study evaluates the efficacy of IONM in predicting post-operative deficits in patients undergoing spinal cord tumor surgery. Materials and Methods: This prospective observational study was conducted at a tertiary care center between January 2019 and August 2021. It involved patients aged 18 and above undergoing surgery for intradural spinal cord tumors (intradural extramedullary and intramedullary [IM] tumors). Pre-operative, intraoperative, and post-operative data, including clinical characteristics and neuromonitoring parameters, were recorded. Neuromonitoring modalities (transcranial Motor-Evoked Potentials [TcMEP], Somatosensory-Evoked Potentials [SSEP], and Trigger Electromyography) were used to assess neurological function. The primary endpoint was post-operative neurological status assessed at 48 h, 1 month, and 3 months. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for each modality. Results: A total of 32 patients were included in the study. The most common symptoms on presentation were pain radiating to limbs and back (84.3%) and motor weakness (81.3%). The study found that TcMEP was the most commonly used neuromonitoring modality. Postoperatively, 87.5% of patients had no neurological deficits, while 12.5% experienced deterioration. Two patients with IM tumors (ependymomas) developed permanent deficits at 3-month follow-up. The sensitivity of TcMEP alone was 75%, with a specificity of 92.8%. SSEP had a sensitivity of 50% and specificity of 100%. When combined, TcMEP and SSEP showed a sensitivity of 60% and specificity of 92.5%. Notably, no significant changes in IONM findings were observed in relation to the tumor location or segmental involvement. Conclusion: IONM is useful in predicting post-operative deficits in spinal cord tumor surgery, though its role in preventing new neurological deficits is limited. Its application should be considered on a case-by-case basis, especially in resource-limited settings. Further studies are needed to assess its cost-effectiveness and broader efficacy.