MRI investigation of the relationship between lumbar disc degeneration and multifidus atrophy

This study was conducted to determine whether a relationship exists between severity of intervertebral disc degeneration and atrophy of the adjacent multifidus muscles. 30 MRIs of patients presenting with low back pain were analyzed. Severity of disc degeneration was assessed at the L4/L5 segmental spinal level. The total multifidus cross-sectional area (CSA) and pure muscle CSA were measured using the OsiriX—DICOM viewer in order to calculate percentage of muscle atrophy on the left and right sides the level above, the level of, and the level below the lesion. In the 15 cases of asymmetric disc herniation, multifidus atrophy was found to be significantly greater on the same side as the lesion compared to the other side, but only for the level below the lesion (32.4% vs. 24.5%; paired-samples t-test, P < 0.000). In addition, significantly greater atrophy was found in individuals with major disc degeneration compared with those with minor disc degeneration, but only for the multifidus muscle on the left side below the level of the lesion (37.3% vs. 27.0%; independent samples t-test, P < 0.05, n = 30). This study contributes to the growing body of research demonstrating that multifidus atrophy is greater on the same side as disc herniation below the level of the lesion. Further, this study is the first to formally demonstrate a relationship between multifidus atrophy and severity of disc degeneration.