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. 2025 May 8:21925682251341820.
doi: 10.1177/21925682251341820. Online ahead of print.

Is Intraoperative Neuromonitoring with SSEPs and EMG Predictable for Postoperative Neurologic Deficit in Posterior Lumbar Fusion Surgery? A Retrospective Cohort Analysis

Marco D Burkhard  1 , Gisberto Evangelisti  1 , Franziska C S Altorfer  1 , Philip K Paschal  1 , Chukwuebuka C Achebe  1 , George Gorgy  1 , Michael J Kelly  1 , William D Zelenty  1 , Federico P Girardi  1 , Darren R Lebl  1 , Alexander P Hughes  1 , Frank P Cammisa  1 , Andrew A Sama  1 , Ronald G Emerson  2 , Gbolabo Sokunbi  1
Affiliations

Is Intraoperative Neuromonitoring with SSEPs and EMG Predictable for Postoperative Neurologic Deficit in Posterior Lumbar Fusion Surgery? A Retrospective Cohort Analysis

Marco D Burkhard et al. Global Spine J. .

Abstract

Study DesignRetrospective, single-center cohort study.ObjectiveTo evaluate intraoperative neuromonitoring (IONM) with free-run electromyography (EMG) and somatosensory evoked potentials (SSEPs) during primary posterior lumbar interbody fusion (PLIF) for degenerative conditions and associations with postoperative motor deficits (PMD).MethodsPatients undergoing PLIF from 2015 to 2020 were reviewed. Revision fusions, deformity corrections, and procedures in proximity to the conus were excluded. Patient characteristics, comorbidities, surgical details and intraoperative EMG and SSEP recordings were reevaluated. PMDs were defined as any decline of ≥1/5 strength grade compared to preoperative. Test accuracy and predictive value of SSEP and EMG events for PMD were calculated.Results401 patients (48.9% females, mean age 61 years, mean BMI 28.6) were included. One- and two-level fusions accounted for 67.8% and 27.7% of cases, respectively, most commonly involving L4/5 (67.8%) and L5/S1 (51.4%). EMG events occurred in 29.4% (n = 118) and SSEP events in 4.5% (n = 18). SSEP events were significantly associated with PMD (P = 0.043), whereas EMG events were not (P = 0.463). In multivariable regression, SSEP events predicted PMD with odds ratios of 3.85 for any SSEP event and OR 10.41 for persistent SSEP signal loss (both P = 0.002). Test performance of SSEP was limited (sensitivity: 13.6%; positive predictive value 16.7%).ConclusionIn posterior lumbar interbody fusion, SSEP events are associated with postoperative motor deficits, whereas EMG events are not. However, the overall test accuracy of IONM in predicting neurologic deficits remains limited. Instead of routine utilization, IONM should be tailored to the individual case.

Keywords: free-run and triggered electromyography; intraoperative neuromonitoring; lumbar fusion; patient safety; postoperative neurologic deficits; somatosensory evoked potentials.

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Conflict of interest statement

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: FPG reports royalties from Lanx, Inc. and Ortho Development Corp.; ownership interest in Centinel Spine, BICMD; consulting fees from Lanx, Inc, Ortho Development Corp, and Sea Spine; and stock ownership in Centinel Spine, Healthpoint Capital Partners, LP; membership of scientific advisory board/other office of Healthpoint Capital Partners, outside the submitted work. DRL reports consulting and advisory roles with Choice Spine and Stryker; consulting for DePuy Synthes; ownership interests in Woven Orthopedic Technologies, Vestia Ventures, MiRus Investment LLC, HS2, LLC, ISPH II, LLC, Remedy Logic, and Viseon, Inc.; research support from Medtronic Sofamor Danek USA, Inc.; and royalties from NuVasive, Inc. and Stryker. APH reports research support from Kuros Biosciences AG and Expanding Innovations, Inc.; private investments in Tissue Connect Systems, Inc.; and fellowship support from NuVasive and ATec, outside the submitted work. FPC reports research support from Camber Spine, Centinel Spine, Choice Spine, DePuy Synthes, and Royal Biologic; ownership interest in 4WEB Medical/4WEB, Healthpoint Capital Partners LP, ISPH II, ISPB III Holdings, VBVP VI LLC, VBVP X LLC, Medical Device Partners II and III, Orthobond Corporation, Spine Biopharma, Tissue Differentiation Intelligence, and Tissue Connect Systems. AAS reports royalties from Ortho Development, DePuy Spine Products/Medical Device Business Services, and Clariance; private investments in Vestia Ventures, MiRUS Investment, ISPH II, ISPH 3, and Centinel Spine (Vbros Venture Partners V); consulting fees from DePuy Spine Products/Medical Device Business Services, Clariance, and Kuros Biosciences AG; and research support from Spinal Kinetics/Orthofix, ourside the submitted work. For the remaining authors none were declared.

Figures

Figure 1.
Figure 1.
Study flowchart.
Figure 2.
Figure 2.
MRI and Radiographic Imaging of Illustrative Case 1. (A) Preoperative axial and sagittal T2-weighted MRI imaging showing a degenerative spondylolisthesis at the level L3/4 with severe central stenosis (top left and right) and facet joint diastasis (bottom left). (B) Anteroposterior and lateral radiographs confirming appropriate implant positioning of the pedicle screw construct and posterior lumbar interbody fusion cage.
Figure 3.
Figure 3.
Intraoperative Neuromonitoring of Illustrative Case 1. (A) IONM report and (B) IONM traces demonstrating the transient loss of bilateral lower extremity SSEPs. Tibial Nerve SSEP Recordings Are Shown.
Figure 4.
Figure 4.
MRI and Radiographic Imaging of Illustrative Case 2. (A) Preoperative MRI. Top left (T2) and bottom left (T1) parasagittal view showing the foraminal stenosis at L4/5 and L5/S1 on the right in place of multilevel degenerative disc disease (T2 midline sagittal on right) (B) Anteroposterior and lateral radiographs confirming appropriate placement of pedicle screws at L4-S1 and PLIF cages.
Figure 5.
Figure 5.
Intraoperative Neuromonitoring of Illustrative Case 2. (A) IONM report and (B) IONM traces demonstrating stable SSEPs and no EMG abnormalities throughout the case. Tibial Nerve SSEP Recordings Are Shown.
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