Study Design.

Retrospective review of institutional data.

Objective.

The aim of this study was to assess the utility of somatosensory-evoked potentials (SSEP) and transcranial electric motor-evoked potentials (MEP) in the resection of spine tumors and evaluate the ability of both single and multi-modal monitoring to predict postoperative neurological deficits.

Summary of Background Data.

Although the utility of intraoperative monitoring (IOM) is well established in scoliosis and degenerative surgery, studies in spine tumor patients have been limited.

Methods.

A series of consecutive patients who underwent resection with the use of IOM at a single institution between August 2009 and March 2013 was identified. Demographic, clinical, and neuromonitoring data were collected preoperatively, during surgery, at the moment of discharge, and at a 6-month follow-up visit. Three cohorts were established based on the anatomical location of the tumor: intramedullary, intradural extramedullary, and extradural. Additional groupings were formed based on spinal region. Patients with significant changes in SSEPs or MEPs during surgery were identified and the rate of neurological deficits was assessed.

Results.

A total of 52 patients were analyzed. A change in SSEPs or MEPs was detected in 11 (21.2%) cases whereas 14 patients (26.9%) developed permanent postoperative deficits. SSEPs predicted deficits in the resection of intramedullary tumors (P= 0.015)(area under cover, AUC= 0.83), and intradural extramedullary tumors (P= 0.048; AUC= 0.70). MEP monitoring did not predict postoperative deficits in the resection of intramedullary (P= 0.21; AUC= 0.69) or intradural extramedullary tumors (P= 0.31; AUC= 0.63). Neither SSEPs nor MEPs predicted deficits for extradural tumors.

Conclusion.

The efficacy of IOM in spine tumor resection is dependent on tumor location relative to the spinal cord and dura. The accuracy of SSEPs and their ability to predict postoperative deficits was greatest for intramedullary lesions. For this series, MEP and multi-modal monitoring did not confer a benefit in predicting permanent neurological deficits.

Level of Evidence: 4

Intraoperative monitoring (IOM) is a common tool used in spine surgery to avoid iatrogenic neurological injury. The value of numerous IOM modalities such as transcranial electric motor-evoked potentials (MEP), somatosensory-evoked potentials (SSEP), and/or electromyography (EMG) is well established in the surgical treatment of various spine conditions. Currently, IOM utilization is considered to be the standard of care in major spine deformity correction. 1–5 However, a few studies have assessed the utility of IOM in predicting postoperative neurological deficits after the surgical treatment of spinal tumors, with even a fewer reporting sensitivity/specificity or correlation values for their cohorts. 6–10 Low reported incidence of neuromonitoring changes and/or postoperative deficits has rendered the evaluation of IOM in spinal tumors difficult. 6, 8, 10, 11 Furthermore, the importance of tumor subtype or location relative to the dura or the cord is not well characterized for this indication. The purpose of this study was thus to retrospectively assess the utility of IOM (MEPs and SSEPs) in predicting persistent, long-term postoperative neurological deficits after the resection of spine tumors stratified by tumor location (intramedullary, intradural extramedullary, and extradural) and spinal region. We hypothesized that IOM use would be significantly associated with long-term deficits for all tumor locations, and have greatest predictive capacity for deficits after intramedullary resection.

MATERIALS AND METHODS

Patient Selection and Data …