Change in the Dimensions of the Lumbar Area Muscles after Surgery: MRI Analysis

C hronic lower back pain is a critical health-related problem, with over 70% lifetime prevalence reported in industrialised counties [1].While 80% of patients with acute lower back pain recover within six weeks, the pain lasts for more than three months in approximately 7%-10% of patients, thereby adversely affecting work performance and the economy [2].Besides the loss in muscle power associated with long-term inactivation and inadequacies in voluntary neural activation, atrophy of type two muscle fibres and changes in connective tis-sues are observed in patients with lower back pain.These changes could be attributed to the non-use and reflex inhibition that result in strength loss in muscles and muscle groups [3].Notwithstanding the primary pathology, other components of the spinal motion segment are also affected in patients with chronic lower back pain [4].Reportedly, leading changes are in the dimensions and symmetry of the paraspinal muscles, which play a vital role in facilitating movements and the formation of posture [5].Some stud-ABSTRACT OBJECTIVE: This study aims to assess the change in the dimensions of the lumbar muscles in patients with chronic lower back pain using Magnetic Resonance Imaging (MRI) and to determine pre/post effects of surgery. METHODS:We enrolled 28 individuals (13F/15M; age: 45.39±11.56years) whose L2-S1 muscle measurements were obtained using MRI, before and at follow-up 6-12 months after surgery.The control group comprising 37 individuals (18F/19M; age: 34.41±10.72years) who had no lumbar pathology but for whom retrospective archive images were available.In the axial MRI analysis, the cross-sections of m.multifidus, mm.erector spinae and m.psoas major on both sides were measured with the 'closed polygon' technique.RESULTS: The L2-3 and L4-5 levels of the m.multifidus on the right side, the L2-3, L4-5 and L5-S1 levels of the m.multifidus and the L5-S1 levels of the mm.erector spinae on the left side cross-sectional areas were significantly lower than the control group (p<0.05).The right-side m.multifidus and the left-side mm.erector spinae sectional areas were significantly lower than the pre-surgery values at the L5-S1 levels (p<0.05).CONCLUSION: This study demonstrated that chronic lower back pain causes atrophy in the lumbar muscles and established the existence and continuity of atrophy after surgery.