Structural Brain Imaging in People With Low Back Pain.

STUDY DESIGN: Cross-sectional study.

OBJECTIVE: The aim of this study was to determine whether low back pain (subacute and chronic) is related to differences in brain volume.

SUMMARY OF BACKGROUND DATA: Inconsistent findings have been reported about the effect of chronic low back pain on brain volume, and the effect of subacute low back pain on brain volume has not been sufficiently investigated.

METHODS: A total of 130 participants were included (23 subacute and 68 chronic low back pain; 39 healthy controls). The main outcome measure was whole and regional brain volume. Clinical outcome measures included pain duration, pain intensity, fear avoidance belief questionnaire, Oswestry Disability Index, and Beck's Depression Inventory.

RESULTS: Decrease in brain volume in several regions was observed in chronic low back pain when compared with health subjects; however, after correcting for multiple comparisons, no significant differences were detected between any of the three groups in whole-brain volume. Regionally, we detected less gray matter volume in two voxels in the middle frontal gyrus in chronic low back pain participants compared with healthy controls. None of the clinical outcome measures were correlated with brain volume measurements.

CONCLUSION: Low back pain (subacute or chronic) is not related to significant differences in brain volume after correction for multiple comparisons. The effect size was too small to detect possible subtle changes unless much larger sample sizes are examined, or it is possible that low back pain does not affect brain volume.

LEVEL OF EVIDENCE: 5.