The Use of Intraoperative Neuromonitoring in Lateral Lumbar Interbody Fusion Surgery

Intraoperative neuromonitoring (IONM) was integrated into most types of spine surgery to help prevent intraoperative nerve injury. Concern has been raised for the actual benefit provided by IONM, particularly in the current era of navigation and robotic guided surgery. The purpose of this study was to investigate IONM changes and postoperative neurologic deficits during lateral lumbar interbody fusion (LLIF).

This was a cross-sectional study on a consecutive series of 202 patients who underwent LLIF procedures from January 2022 to September 2022. Patients were included if 18 years of age or older and underwent fusion at one, two, or three levels. Data were collected from patient chart review and operative reports, including intraoperative changes in neuromonitoring. Postoperative clinic notes were reviewed for up to approximately three months postoperatively for indication of neurologic injury. IONM was conducted using somatosensory evoked potential (SSEP).

There were two false negatives in this cohort (1.00%), involving no IONM change but exhibiting a neurologic deficit postoperatively. There was one true positive (0.50%) involving a reported IONM change and postoperative neurologic deficit; however, the IONM change occurred just after the patient was flipped prone for the posterior instrumentation portion of the LLIF procedure. The surgeon confirmed through new imaging that the fusion cage was in the appropriate position.

This study found that changes in IONM were rare (0.50%). In the case of the one true positive, this occurred during repositioning, and the IONM change was not successful as a preventative measure. These results indicate that the use of SSEPs may not be supported for the LLIF approach. While medico-legal concerns promote its usage, the low rates of neurologic deficits and costs associated with IONM should be considered, leading to a reexamination of its use in LLIF spinal surgery.