Utility of somatosensory- and motor-evoked potential change thresholds in surgical treatment for thoracic spinal stenosis based on different pathologies

Tun Liu; Gang Wu; Wentao Wang; Huaguang Qi; Songchuan Zhao; Jitao Zhang; Ruiguo Wang; Tao Yuan; Li Xiao; Zhenguo Luo; Weizhou Yang; Fei Wang; Gang Wang; Liang Yan

doi:10.1016/j.spinee.2024.04.026

Utility of somatosensory- and motor-evoked potential change thresholds in surgical treatment for thoracic spinal stenosis based on different pathologies

Spine J. 2024 Apr 27:S1529-9430(24)00198-0. doi: 10.1016/j.spinee.2024.04.026. Online ahead of print.

Authors

Tun Liu¹, Gang Wu¹, Wentao Wang², Huaguang Qi³, Songchuan Zhao², Jitao Zhang², Ruiguo Wang², Tao Yuan³, Li Xiao¹, Zhenguo Luo¹, Weizhou Yang⁴, Fei Wang⁵, Gang Wang⁶, Liang Yan⁷

Affiliations

¹ Department of Anesthesiology, Xi'an Honghui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, China.
² Department of Spine Surgery, Xi'an Honghui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, China.
³ Department of Functional Inspection Section, Xi'an Honghui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, China.
⁴ Department of Spine Surgery, the first affiliated hospital of Xi'an Jiaotong University Health Science Center, Xi'an, China.
⁵ Institute of Orthopedic Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
⁶ The Key Laboratory of Biomedical Information Engineering, Ministry of Education, Institute of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
⁷ Department of Spine Surgery, Xi'an Honghui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, China. Electronic address: ionm001@163.com.

PMID: 38685275
DOI: 10.1016/j.spinee.2024.04.026

Abstract

Background context: Thoracic spinal stenosis (TSS) is secondary to different pathologies that differ in clinical characteristics and surgical outcomes.

Purpose: This study aimed to determine the optimal warning thresholds for combined somatosensory-evoked potentials (SSEP) and motor-evoked potentials (MEP) for predicting postoperative neurological deterioration in surgical treatment for TSS based on different pathologies. Additionally, we explored the correlation between SSEP/MEP monitoring and postoperative spinal neurological function.

Study setting: Retrospective study.

Patient sample: Two hundred and five patients.

Outcome measures: We obtained perioperative modified Japanese Orthopedic Association (mJOA) scores to assess spinal neurological function.

Methods: The data collected in this study included demographic data, intraoperative neurophysiological monitoring (IONM) signals, and perioperative neurological function assessments. To determine the optimal IONM warning threshold, a receiver operating characteristic (ROC) curve was used. Additionally, Pearson correlation analysis was conducted to determine the correlation between IONM signals and clinical neurological conditions.

Results: A total of 205 consecutive patients were eligible. Forty-one patients had thoracic disc herniation (TDH), 14 had ossification of the posterior longitudinal ligament (OPLL), 124 had ossification of the ligamentum flavum (OLF), and 26 had OPLL+OLF. The mean mJOA scores before surgery and 3 months after surgery were 7.0 and 7.9, respectively, resulting in a mean mJOA recovery rate (RR) of 23.1%. The average postoperative mJOA RRs for patients with TDH, OPLL, OLF, and OPLL+OLF were 24.8%, 10.4%, 26.8%, and 11.2%, respectively. Patients with OPLL+OLF exhibited a more stringent threshold for IONM changes. This included a lower amplitude cutoff value (a decrease of 49.0% in the SSEP amplitude and 57.5% in the MEP amplitude for short-term prediction) and a shorter duration of waveform change (19.5 minutes for SSEP and 22.5 minutes for MEP for short-term prediction). On the other hand, patients with TDH had more lenient IONM warning criteria (a decrease of 49.0% in SSEP amplitude and 77.5% in MEP amplitude for short-term prediction; durations of change of 25.5 minutes for SSEP and 32.5 minutes for MEP). However, OPLL patients or OLF patients had moderate and similar IONM warning thresholds. Additionally, there was a stronger correlation between the SSEP amplitude variability ratio and the JOA RR in OPLL+OLF patients, while the correlation was stronger between the MEP amplitude variability ratio and the JOA RR for the other three TSS pathologies.

Conclusions: Optimal IONM change criteria for prediction vary depending on different TSS pathologies. The optimal monitoring strategy for prediction varies depending on TSS pathologies.

Keywords: Motor-evoked potential (MEP); Ossification of the ligamentum flavum (OLF); Ossification of the posterior longitudinal ligaments (OPLL); Somatosensory-evoked potential (SSEP); Thoracic disk herniation (TDH); Thoracic spinal stenosis (TSS).