The Relationship of Lumbar Multifidus Muscle Change to Disc Hernia and Low Back Pain: An Magnetic Resonance Imaging Study

Introduction: Our aim was to evaluate the relationship between lumbar multifidus (LM) muscle atrophy and lumbar disc herniation by magnetic resonance imaging (MRI) findings in patients with low back pain. Methods: Lumbar MRI of 264 patients aged between 18 and 80 years who had a history of back pain for at least 6 months were evaluated retrospectively for LM muscle atrophy. LM muscle atrophy was evaluated at L4-5 and L5-S1 levels in axial T2-weighted images. The lumbar MRI of the patients were evaluated for LM muscle atrophy and lumbar intervertebral disc herniation. The relationship of LM muscle atrophy to lumbar intervertebral disc herniation and back pain was investigated statistically. Results: Of 264 (147 female, 117 male) patients, 88 patients (33.3%) had grade 0 atrophy, 135 (51.1%) had grade 1 atrophy and 41 (15.5%) had grade 2 atrophy. The prevalence of LM muscle atrophy was 73.5% in females and 49.8% in males. In 210 of 264 patients, intervertebral disc herniation was detected at any level in the lumbar spine. Of these 210 patients, 150 (71%) had grade 1 and 2 LM muscle atrophy. Spinal canal stenosis, intervertebral disc herniation and nerve root compression were not detected in 54 of 264 patients. Of these 54 patients, 28 had grade 0 atrophy, 23 had grade 1 atrophy and 3 had grade 2 atrophy. Conclusion: In our study, 9.8% of patients with low back pain had grade 1 and 2 LM muscle atrophy without accompanying spinal canal stenosis, intervertebral disc herniation or nerve root compression. LM muscle atrophy alone may be the cause of low back pain in patients with normal MRI.