ABSTRACT
Objective:To study the correlation between the quartering of nerve root subsidence sign (NRS) and the cross-sectional area (CSA) of the narrow segment thecal sac in patients with lumbar spinal stenosis (LSS).Methods:The data of 203 LSS patients in the Fourth People′s Hospital of Hengshui from January 2020 to December 2021 were retrospectively analyzed. All patients underwent MRI cross sectional scanning. The patients were divided into positive type a group ( n=62), positive type b group ( n=32), positive type c group ( n=51), and negative group ( n=58) by NRS quartering method. The minimum CSA, median sagittal diameter (PAD), and lateral recess sagittal diameter of each group were compared. The correlation between NRS quartering classification and the minimum CSA and related indicators of lumbar spinal stenosis was analyzed. Results:The minimum CSA, PAD, and sagittal diameter of the lateral recess in the positive a group, positive b group, and positive c group were all smaller than those in the negative group, while the Visual Analogue Scale (VAS) score and Oswestry Disability Index (ODI) were higher than those in the negative group; The minimum CSA, PAD, and sagittal diameter of the lateral recess in the positive b type and positive c type groups were smaller than those in the positive a type group, while the VAS score and ODI index were higher than those in the positive a type group; The minimum CSA, PAD, and sagittal diameter of the lateral recess in the positive c type group were smaller than those in the positive b type group; The VAS score and ODI index were higher than those of the positive b type group; The differences were statistically significant (all P<0.05). 203 patients were divided into 54 normal cases, 58 mild stenosis cases, 49 moderate stenosis cases, and 42 severe stenosis cases based on the minimum CSA. The coincidence rate between negative NRS and minimal CSA diagnosis as normal was 94.44%(51/54), the coincidence rate between positive type a and minimal CSA diagnosis as mild stenosis was 84.48%(49/58), the coincidence rate between positive type b and minimal CSA diagnosis as moderate stenosis was 53.06%(26/49), and the coincidence rate between positive type c and minimal CSA diagnosis as severe stenosis was 90.48%(38/42). Using the kappa consistency test, the kappa value for quantitative diagnosis of minimum CSA stenosis in NRS and LSS patients was 0.743, indicating good consistency. The kappa values for quantitative diagnosis of NRS, sagittal diameter of lateral recess, and PAD stenosis were 0.271 and 0.335, with poor consistency. NRS typing was negatively correlated with CSA and PAD ( r=-0.723, -0.581, all P<0.001), and positively correlated with VAS score and ODI index ( r=0.473, 0.640, all P<0.001). Conclusions:The NRS quartering method has a good consistency in diagnosing the severity of LSS patients and the minimum CSA of stenosis segments, suggesting that the NRS quartering method can better reflect the degree of Spinal stenosis, which can not only be used as an auxiliary indicator for qualitative diagnosis of LSS, but also has a high value in quantitative diagnosis.