基于MRI的脊髓矢状面分型用于先天性脊柱后凸矫形术中神经电生理监测事件的风险预测

A novel spinal cord classification system:predict Intraoperative Neuromonitoring Event during correction of congenital kyphosis

目的根据先天性脊柱后凸患者矢状面MRI T2WI上顶椎区脊髓在椎管中的形态及相对位置提出新的脊髓矢状面分型,探讨不同脊髓矢状面分型患者术中神经监测事件(intraoperative neuromonitoring event,IONME)的发生率及其危险因素。方法回顾性分析2016年1月至2021年12月于南京鼓楼医院接受矫形手术治疗的85例先天性脊柱后凸患者的临床资料,男43例、女42例,年龄(14.6±6.1)岁(范围2~32岁)。根据矢状面MRI T2WI显示顶椎区脊髓在椎管中的形态及相对位置分为三型:A型定义为顶椎区脊髓位于椎管中央,脊髓四周均可见脑脊液;B型定义为顶椎区脊髓紧贴椎管前壁,腹侧无脑脊液,脊髓形态未发生改变;C型定义为顶椎区脊髓紧贴椎管前壁,脊髓受压形态改变。85例中A型5例(6%)、B型33例(39%)、C型47例(55%)。术前测量最大后凸角(global kyphosis,GK)和矢状面畸形比(sagittal deformity angular ratio,SDAR),记录术中IONME发生情况。IONME组和非IONME组患者临床及影像学资料比较采用χ^(2)检验或独立样本t检验,采用单因素分析筛选潜在危险因素,采用二分类logistic回归分析确定发生IONME的独立危险因素。结果纳入研究的85例患者中27例(32%)发生IONME,包括B型2例、C型25例。三组患者IONME发生率分别为0、6%和53%,差异有统计学意义(χ^(2)=27.15,P<0.001)。IONME组与非IONME组患者GK、SDAR和顶椎区位置的差异均有统计学意义(t=5.41,P<0.001;t=3.65,P<0.001,χ^(2)=7.71,P=0.005)。单因素分析结果显示脊髓矢状面分型C型(OR=20.46,P<0.001)、GK(OR=1.07,P<0.001)、SDAR(OR=1.15,P=0.002)和顶椎位于中胸椎(OR=4.30,P=0.008)为发生IONME的潜在危险因素。二分类logistic回归分析显示GK(OR=1.05,P=0.015)、脊髓矢状面分型C型(OR=6.22,P=0.042)和顶椎位于中胸椎(OR=6.43,P=0.021)为发生IONME的独立危险因素。脊髓矢状面分型C型患者中顶椎位于中胸椎的患者14例,其中11例(79%)发生IONME;顶椎位于下胸椎的患者33例,其中14例(42%)发生IONME,差异有统计学意义(χ^(2)=5.16,P=0.023)。结论先天性脊柱后凸畸形患者矫形手术中发生IONME的危险因素包括脊髓矢状面分型C型、GK和顶椎位于中胸椎。术前基于MRI脊髓矢状面分型对先天性脊柱后凸畸形患者矫形术中IONME的发生具有良好的预测价值。

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.