Diagnostic Value Of Nerve Root Sedimentation Sign For Lumbar Spinal Stenosis

ObjectiveTo preliminarily explore the role of Nerve root sedimentation sign(NRS)in the diagnosis of Lumbar spinal stenosis(LSS)by analysis of the correlations between multiple clinical imaging indicators including NRS and the diagnosis of spinal canal stenosis.MethodsThis is a retrospective radiologic study.From May 2015 to August 2018,162patients who carried out MR examination due to backache together or intermittent claudication were selected.The radiological parameters were measured and calculated including:NRS classification,posteroanterior diameter(PAD),cross-sectional area(CSA),cross-sectional area of the canal(CAC),sagittal diameter of lateral recess and cross-sectional area change rate.All the selected segments were divided into spinal stenosis and non-stenosis groups according to the ratio of CSA/CAC.Single factor analysis and multiple logistic regression analysis about above imaging indicators between the two groups were conducted to analyze the key factors causing the diagnosis of spinal canal stenosis.When these segments were stratified by CSA,the sensitivity and specificity of NRS were compared in groups with variously radiologic stenosis.ResultsA total of 316 segments were included in the experiment,including 229 cases of spinal stenosis and 87 cases of non-stenotic segments.Single factor analysis analysis showed:the diagnosis of spinal canal stenosis was directly related with NRS,PAD,CSA,sagittal diameter of lateral recess and cross-sectional area change rate(p<0.05).Multiple logistic regression analysis showed that NRS positive b type(with negative reference),CSA less than normal(180±50 mm~2)is risk factors for the diagnosis of spinal canal stenosis(p<0.05),while the rest classifications of the NRS and other imaging indicators were not relevant.The NRS had a sensitivity of 61.14%and specificity of 79.31%in the whole segments.When these segments were stratified by CSA,the NRS had a sensitivity of 94.87%,specificity of 66.47%and a Youden Index of 0.62 in segments with CSA<100 mm~2(severe radiologic stenosis),sensitivity of21.79%,specificity of 83.33%and Youden Index of 0.05 in patients with CSA130~180mm~2(moderate radiologic stenosis),and sensitivity of 67.12%,specificity of58.33%and Youden Index of 0.25 in patients with CSA 100~130 mm~2(mild radiologic stenosis).Conclusion1.NRS has high sensitivity and specificity for the diagnosis of severe morphological stenosis,and has a high diagnostic value.2.The new four-type method of NRS can better reflect the degree of spinal stenosis3.NRS have no superiority over CSA in the diagnosis of spinal canal stenosis without obvious morphological changes.The diagnostic value is limited.