Magnetic resonance spectroscopic analysis of multifidus muscles lipid content and association with spinopelvic malalignment in chronic low back pain

Abstract

Objective: To analyze intramyocellular lipids (IMCLs) and extramyocellular lipids (EMCLs) of the multifidus muscle (Mm) using MR spectroscopy in chronic low back pain (CLBP) and control groups and to identify correlations with spinopelvic alignment.

Methods: 40 patients (16 males, 24 females; mean age, 62.9 ± 1.9 years) whose visual analogue scale scores were >30 mm for CLBP were included. Furthermore, 40 control participants matched with the CLBP group subjects by sample size, gender and age (17 males, 23 females; mean age, 65.0 ± 1.2 years) were included. We compared the body mass index, physical workload, leisure time physical activity level, spinopelvic parameters, and IMCLs and EMCLs of the Mm between the groups. We also evaluated possible correlations of spinopelvic parameters with IMCLs and EMCLs of the Mm in the groups.

Results: There were no statistically significant differences in body mass index, physical workload, exercise intensity level, spinopelvic parameters and EMCLs between the groups. The IMCLs were significantly higher in the CLBP group than in the control group (p < 0.01). In the CLBP group, there was a significantly negative correlation between IMCLs and lumbar lordosis (r = -0.64, p < 0.01) and a significantly positive correlation between IMCLs and sagittal vertical axis (r = 0.43, p < 0.01).

Conclusion: The measurement of IMCLs might be a characteristic finding of CLBP as well as a precursor to spinal deformity. Advances in knowledge: IMCLs of the Mm may be a useful prognostic marker in rehabilitation strategies for patients with CLBP.

Figure 1.

Sagittal spinal radiologic parameters were recorded as follows: (a) lumbar lordosis (the superior endplate of L1 to the superior endplate of S1) and thoracic kyphosis (the superior endplate of T4 to the inferior endplate of T12), and (b) sagittal vertical axis (the horizontal offset from the posterior–superior corner of S1 to the vertebral midbody of C7).

Figure 2.

Pelvic parameters were recorded as follows: (a) sacral slope (the angle between the horizontal and upper sacral endplate), (b) pelvic tilt (the angle between the vertical and line through the midpoint of the sacral plate to the femoral head axis) and (c) pelvic incidence (the angle perpendicular to the upper sacral endplate at its midpoint and the line connecting this point to the femoral head axis).

Figure 3.

Volume of interest for MR spectroscopy measurements was set right of the multifidus muscle as indicated on the T₂ weighted image at the L4/L5 level.

Figure 4.

Proton MR spectrum of the Mm analyzed using LCModel software (Stephen Provencher, Inc., Oakville, ON). The following metabolites are identified: intramyocellular lipids (IMCLs) (–CH₂) methylene protons at 1.3 ppm; extramyocellular lipids (EMCLs) (–CH₂) methylene protons at 1.5 ppm.

Figure 5.

Comparisons of (a) intramyocellular lipids (IMCLs) and (b) extramyocellular lipids (EMCLs) of the multifidus muscle in the chronic low back pain (CLBP) and control groups. IMCLs were higher in the CLBP group, and EMCLs were not significantly difference between the CLBP and control groups. Data are shown as mean ± standard error of the mean. *p < 0.01 CLBP vs control: Mann–Whitney U test.

Figure 6.

Relationship among intramyocellular lipids (IMCLs), lumbar lordosis (LL) and sagittal vertical axis (SVA) in the chronic low back pain group. (a) The correlation coefficient between IMCLs and LL indicated significantly negative correlation. (b) The correlation coefficient between IMCL and SVA indicated significantly positive correlation.