UTILITY OF INTRAOPERATIVE NEUROPHYSIOLOGICAL MONITORING IN DETECTING MOTOR AND SENSORY NERVE INJURIES IN PAEDIATRIC HIGH-GRADE SPONDYLOLISTHESIS

The use of intraoperative neuromonitoring (IONM) during the surgical correction of spinal deformity has been shown to reduce iatrogenic injury in both the pediatric and adult populations. Although motor-evoked potentials (MEP), somatosensory-evoked potentials (SSEP), and electromyography (EMG) have been shown to be highly sensitive and specific in detecting spinal cord and nerve root injuries, their utility in detecting motor and sensory nerve root injury in pediatric high-grade spondylolisthesis (HGS) remains unknown. We aim to assess the diagnostic accuracy and therapeutic impact of unimodal and multimodal IONM in the surgical management of HGS. A retrospective cohort study was conducted and data on patient demographics, spinopelvic and spondylolisthesis parameters, and the presence of pre-and post-operative neurological deficits were collected. Intraoperative MEP, SSEP and EMG alerts were recorded. Alert criteria were defined as a change in amplitude of more than 50 percent for MEP and/or SSEP, with or without change in latency, and more than 10 seconds of sustained EMG activity. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for each modality and for the combination of MEP and SSEP. The 95% confidence intervals (CIs) were calculated using the exact (Clopper-Pearson) method. 54 paediatric patients with HGS undergoing posterior spinal fusion (PSF) between 2003 – 2021 in a single tertiary centre were included. 72% (39/54) of patients were female, average age of patient 13.7± 2.3years, and average weight 54.5 ± 9.3 kg. The sensitivity of MEP in detecting new post-operative neurologic deficit was 92.3% (95% CI [64.0 to 99.8]), SSEP 77.8% (95% CI [40.0 to 97.2]), EMG 69.2 (95% CI [38.6 to 90.9]), and combination MEP and SSEP 100% (95% CI [73.5 to 100]). The specificity of MEP was 80.0% (95% CI [64.4 to 91.0]), SSEP 95.1% (95% CI [83.5 to 99.4]), EMG 65.9 (95% CI [49.4 to 79.9]), and combination MEP and SSEP 82.9% (95% CI [67.9 to 92.9]). The accuracy of SSEP was 92.0% (95% CI [80.8 to 97.8%]) and combination of MEP and SSEP was 86.8% (95% CI [74.7 to 94.5%]). 12 (22.2%) patients had a new motor or sensory deficit immediately postoperatively. Nine patients made a full recovery and 3 improved. Unimodal IONM using SSEP and MEP alone were accurate in diagnosing sensory and motor nerve root injuries, respectively. The diagnostic accuracy in predicting motor and sensory nerve injuries in pediatric HGS, improved further with the use of multimodal IONM (combining MEP and SEP). We recommend the utilization of multimodal IONM in all HGS posterior spinal (PSF) surgeries.