Correlation Between Lower Back Pain And Atrophy Of Multifidus Muscle In Patients With Lumbar Spinal Stenosis

Objective To analyze the correlation between the degree of atrophy of the multifidus muscle in degenerated segments and the degree of spinal stenosis in patients with lumbar spinal stenosis,and to compare whether there is a difference between the degree of atrophy of the multifidus muscle in stenotic and non-stenotic segments,and whether there is a correlation between the atrophy of the multifidus muscle and lower back pain.Methods Retrospective analysis of the data of patients with 104 cases of lumbar stenosis seen in our hospital from 2008 to 2019,22 cases(21%)in men and 82 cases(79%)in women;age(58.60±8.93)years(range:38-77 years).10 cases(9.6%)of L5/S1 stenosis,82 cases(78.8%)of L4/5 stenosis,10 cases of L3/4 stenosis(9.6%),and L2/3 stenosis in 2 cases(1.9%).All patients underwent MR examination of the lumbar spine at the time of consultation,and the VAS score of lower back pain at the time of MR examination was obtained.The patients’ MR imaging data were obtained,and the data were measured using Image-Pro Plus 6.0 software.The total multifidus muscle cross sectional area(TCSA),fat-free multifidus muscle cross sectional area(FCSA),and FCSA were measured in the stenotic segment of the lumbar spine on MR.area(FCSA),and the FCSA/TCSA ratio.This ratio was used to assess the degree of atrophy of the multifidus muscle,with larger values indicating less fat-infiltrated area and less severe atrophy;the TCSA,FCSA,and FCSA/TCSA ratios were measured for the preceding non-stenotic segment of the stenotic segment.The degree of spinal stenosis in the stenotic segment was graded using the grading of spinal stenosis proposed by Shizas et al.The degree of stenosis was classified into four grades,A,B,C and D,from mild to severe.The degree of muscular atrophy between segments was determined using paired t-tests;the correlation between the degree of muscular atrophy in the stenotic segment and the degree of spinal stenosis was analyzed by one-way ANOVA.The Pearson test was used to correlate the VAS score of lower back pain with the degree of myalgia.P<0.01 was set to be statistically significant.Results Among 104 patients,24(22.8%)had grade A stenosis,31(29.8%)had grade B stenosis,27(25.9%)had grade C stenosis,and 22(21.1%)had grade D stenosis.A paired-sample t-test was performed on the degree of multifidus atrophy(FCSA/TCSA ratio)in the stenotic segment and the degree of multifidus atrophy(FCSA/TCSA ratio)in the non-stenotic segment above the stenotic segment,and the t-value was-12.64,with a p-value of 0.00,both of which were statistically significant.The one-way ANOVA of the degree of stenosis of the stenotic segment and the degree of atrophy of the segmental multifidus(FCSA/TCSA ratio)showed a significant difference with a P value of 0.000,and the FCSA/TCSA ratio was significantly different between the two groups with grade A and B stenosis and the two groups with grade C and D stenosis by the Student-Newman-Keuls test.A Pearson test was performed on the VAS score of lower back pain and the degree of atrophy of the multifidus muscle(FCSA/TCSA ratio)with γ=-0.538 and sig=0.000,indicating a moderate negative correlation between the VAS score of lower back pain and the FCSA/TCSA ratio of the stenotic segment and a positive correlation with the degree of atrophy of the multifidus muscle.Conclusion Patients with lumbar spinal stenosis have more severe atrophy of the multifidus muscle in the stenotic segment than in the normal segment.The degree of atrophy of the multifidus muscle in the stenotic segment was positively correlated with the degree of stenosis in the corresponding segment.There was a correlation between lower back pain and atrophy of the multifidus muscle,and the VAS score of low back pain was higher in those with higher atrophy.