MRI Analysis of Paraspinal Muscle Morphology in Patients With Chronic Low Back Pain: A Case-Control Study

Chronic low back pain (CLBP) is a major contributor to musculoskeletal disability worldwide. The paraspinal muscles, particularly those along the thoracolumbar spine, are essential for spinal stability and extension. Morphological alterations in these muscles may have diagnostic and therapeutic implications. This study aimed to determine the cross-sectional area (CSA) of each paraspinal muscle at the level of the L4 superior endplate in patients with chronic back pain (CBP) compared to age-matched individuals without any history of low back pain. We hypothesized that patients with CLBP would demonstrate selective reductions in the CSA of the multifidus, while the psoas major (PS) would remain relatively preserved.

A cross-sectional observational study was conducted with 80 participants: 40 patients with CBP and 40 age-matched controls without low back pain. The PS, multifidus, erector spinae (ES), and quadratus lumborum (QL) muscles were assessed bilaterally using magnetic MRI. An independent t-test was used to assess the statistical significance between the two groups, with significance set at p < 0.05.

The mean ages of the cases and controls were 50.54 and 49.94 years, respectively, with no statistically significant difference. Among the paraspinal muscles evaluated, statistically significant differences in the CSA were found in the multifidus, ES, and QL muscles, but not in the PS.

Statistically significant reductions in the CSA were observed in most paraspinal muscles, except for the PS, in patients with CBP. These preliminary, hypothesis-generating findings highlight the potential value of paraspinal muscle assessment in CLBP and warrant confirmation in larger, multi-center studies before therapeutic implications can be considered.