Clinical Significance of Improved Intraoperative Neurophysiological Monitoring Signal during Spine Surgery: A Retrospective Study of a Single-Institution Prospective Cohort

Abstract

Study Design: Retrospective case series. Purpose: We reviewed the cases that showed significant improvement of intraoperative neurophysiological monitoring (IONM) signals during spine surgery to assess whether there is a correlation with signal improvement and postoperative clinical status and its clinical significance. Overview of Literature: To reduce the risk of neural injury, many spine surgeons are using multimodality IONM. Although many studies attempted to identify valid alarm criteria for predicting postoperative neurologic deterioration, studies concerning the improvement of IONM signals are rare. Methods: We reviewed all spine surgery cases with IONM data treated at our department between January 2013 and May 2017. We found cases showing significant IONM signal improvements. We prospectively analyzed the neurological and clinical outcomes of these patients and compared outcomes pre-and postoperatively. Results: Among 317 cases with the IONM data, we found 29 cases that showed IONM signal improvement compared with baseline. There were 27 cases of compressive myelopathy: 22 had a degenerative cause at the cervical spine, and five, at the thoracic spine. There were two cases of huge neurogenic tumor each at the craniovertebral junction and at the lumbar spine. Both motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SSEPs) signals were improved in six cases, only the MEPs signal improved in 10, and only SSEP signal improved in 13 cases. All cases showed the IONM signal improvement consistently after the decompression procedure during surgery. All patients had a significant improvement in neurological function and subjective symptoms, and none had neurologic deterioration postoperatively. Conclusions: Improvement of IONM signals during surgery may indicate that no unrecognized neural injury occurred during surgery and a favorable postoperative neurological outcome can be expected.

Which Factors Affect the Stress of Intraoperative Orthopedic Surgeons by Using Electroencephalography Signals and Heart Rate Variability?

“…However, specifying these predictions with actual numerical values and parameters that have been validated has another important meaning. Numerous studies have been conducted on several factors related to the surgical outcome [30][31][32]. These are the demographic data of the patients before surgery, radiologic parameters of the patients undergoing surgery, and factors related to surgery such as operation time and intraoperative blood loss.…”

Transcranial Electrical Motor Evoked Potential in Predicting Positive Functional Outcome of Patients after Decompressive Spine Surgery: Review on Challenges and Recommendations towards Objective Interpretation

“…Another study was made by Wi et al [ 14 ] on 29 improved IONM of spine cases compared to the baselines out of 317 cases with IONM of spine cases and their clinical significance. The surgeries' IONM data were chosen between January 2013 and May 2017.…”

A Comparative Study on the Minimal Invasiveness of Full-Endoscopic and Microendoscopic Cervical Foraminotomy Using Intraoperative Motor Evoked Potential Monitoring

“…There are a few reports that MEP amplitude significantly increased after spinal cord decompression. [ 8 , 9 , 15 ]. In these studies, MEP amplitude was related to clinical outcome measures.…”

“…On the other hand, only two previous studies have focused on neurological improvement or surgical decompression of the spinal cord. In those studies, intraoperative MEP amplitude significantly improved during surgical decompression, and Wang et al found a cut-off value of 150%, and Wi et al found a cut-off value of 200% [ 8 , 9 ]. Our result is similar to those, but further data are needed to determine the cut-off point.…”

“…However, no comparative study has quantitatively evaluated the minimal invasiveness of FECF and MECF in terms of neurological function. Recent studies have shown that nerve decompression results in an increase in intraoperative transcranial electrical stimulation motor evoked potential (MEP) amplitude [ 8 , 9 ]. The aim of this study was to compare the neurological invasiveness of FECF and MECF using intraoperative MEP monitoring.…”