Iatrogenic nerve injury is one of the most severe complications of surgical correction for spinal deformity with different etiologies.The intraoperative neurophysiological monitoring (IONM) has been widely used to detect the nerve injury in spinal correction surgery.The commonly used IONM techniques involve somatosensory evoked potential (SEP),motor evoked potentials (MEP) and electromyography (EMG).All the IONM techniques have both advantages and disadvantages,while combing SEP,MEP and EMG in the spinal correction surgery could maximumly improve the accuracy and reliability of the IONM.The different pathophysiology of patients with spinal deformity due to different etiologies might significantly decrease the success rate,sensitivity,and specificity of IONM,which might further decrease the reliability of IONM.However,the IONM still serves as the most important monitoring method for the iatrogenic nerve injury in patients with different spinal deformity due to different etiologies.For those monitoring changes that cannot be distinguished,the wake-up test is still the gold standard.

Objective To evaluate the effects of different levels of neuromuscular blockade(NMB)on transcranial electric motor-evoked potentials(TCeMEPs)during idiopathic scoliosis.Methods Thirty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes,aged 11-23 yr,weighing 31-62 kg,scheduled for elective idiopathic scoliosis under general anesthesia,were enrolled in the study.NMB was monitored with train of four(TOF)-Watch SX.The levels of partial NMB were classified into 5 states according to TOF ratio(TOFR)and TOF counts:1 or 2 TOF counts(TOF1),3 TOF counts and TOFR≤15%(TOF2),TOFR 16%-25%(TOF3),TOFR 26%-50%(TOF4),TOFR 51%-75%(TOF5) and TOFR>75%(no NMB).Each state was maintained for 10 min.Failure and false-positive findings in TCeMEP monitoring,development of unexpected body movement and satisfaction with NMB were recorded.Results Compared with no NMB,the failure and false-positive rates of TCeMEP monitoring were significantly increased,the incidence of unexpected body movement was decreased,and the rate of satisfactory NMB was increased at TOF1,TOF2 and TOF3(P<0.05),no significant change was found in failure or false-positive rates of TCeMEP monitoring at TOF4 and TOF5(P>0.05),and the incidence of unexpected body movement was decreased and the rate of satisfactory NMB was increased at TOF4,the rate of satisfactory NMB was increased at TOF5(P<0.05),and no significant change was found in the incidence of unexpected body movement at TOF5(P>0.05).Compared with those at TOF4,no significant change was found in the failure or false-positive rates of TCeMEP monitoring(P>0.05),the incidence of unexpected body movement was significantly increased,and the rate of satisfactory NMB was decreased at TOF5(P<0.05).Conclusion Maintaining TOFR at 26%-50% the partial NMB during surgery does not affect TCeMEP monitoring during idiopathic scoliosis and meets the intra-operative NMB requirements simultaneously,and it is the optimum NMB for this type of surgery.

Objective:To propose a novel classification system based on the morphology and relative position of spinal cord in the spinal canal at sagittal T2-MRI, and to investigate the incidence and risk factors of the intraoperative neuromonitoring event (IONME) across these classifications.Methods:From January 2016 to December 2021, a consecutive cohort of 85 patients who underwent surgical correction of congenital kyphosis with pedicle screw/rod constructs were retrospectively reviewed, including 43 males and 42 females, aged 14.6±6.1 years old. According to the morphology and relative location of spinal cord at the apex of the curve on the sagittal-T2 MRI, patients were divided into three groups. Type A (5 cases) is characterized by the spinal cord centrally positioned within the spinal canal, surrounded by discernible cerebrospinal fluid (CSF). Type B (33 cases) depicts the spinal cord abutting the spinal canal's anterior wall, maintaining its intrinsic morphology. In Type C (47 patients), the spinal cord is contorted by the apical vertebral body, devoid of interposing CSF. The global kyphosis (GK) and sagittal deformity ratio (SDAR) of patients were measured before surgery. The incidence of IONME were recorded. All patients included in the study were further divided into the IONME group and the non-IONME group. Potential risk factors were identified using univariate testing. Binary Logistic Regression was used to analyze the independent risk factors for IONM.Results:All of 85 patients were reviewed: 5 (5.9%) Type A; 33 (38.8%) Type B; and 47 (55.3%) Type C spinal cords. Intraoperatively, 27 (31.8%) instances presented with lost trans-cranial motor-evoked potentials (MEPs) and/or somatosensory evoked potentials (SSEPs). Of these, 2 (7.4%) were Type B, and 25 (92.6%) were Type C, reflecting a statistically significant variance in IONME occurrences across types (χ 2=27.15, P<0.001). Notable differences were observed between IONME and non-IONME groups concerning GK, SDAR, and apex location ( t=5.41, P<0.001; t=3.65, P<0.001; χ 2=7.71, P=0.005). Univariate analysis showed that potential risk factors of IONME included Type C spinal cord ( OR=20.46, P<0.001), higher GK ( OR=1.07, P<0.001), SDAR ( OR=1.15, P=0.002) and apical vertebrae located at middle thoracic( OR=4.30, P=0.008). Independent predictors identified on binary Logistics regression modeling included higher GK ( OR=1.05, P=0.015), Type C spinal cord ( OR=6.22, P=0.042) and apex located at middle thoracic ( OR=6.43, P=0.021). Specifically, within Type C, 79% of cases where the apical vertebra was mid-thoracic experienced IONME, contrasting the 42% incidence observed in those with a lower thoracic apex positioning, signifying a notably elevated IONME likelihood for the mid-thoracic region (χ 2=5.16, P=0.023). Conclusion:Risk factors of IONME included Type C spinal cord, higher GK and apex located at middle thoracic during correction of congenital kyphosis. Preoperative MRI spinal cord typing showed great predictive value for IONME.