Title : Microscopic changes in the multifidus muscle in people with low back pain associated with lumbar disc herniation
Abstract:
Lumbar Disc Herniation (LDH) is a common degenerative condition causing Low Back Pain (LBP) and neuropathic pain due to nerve root irritation and compression. Previous studies have examined the microscopic changes in the spinal extensor muscles in people with LBP, with the MultiFidus (MF) being the most studied in people with LDH due to its uni-segmental innervation. However, there are conflicting findings regarding the MultiFidus (MF) muscle's microscopic changes in LDH patients. So, this observational study aimed to compare the affected MF to the adjacent MF on the ipsilateral and contralateral sides in LDH patients and examined correlations with clinical features of LBP. Four muscle biopsies were collected from each of 30 surgical participants. Immunohistochemistry was performed on tissue sections and imaged with an epifluorescence microscope. Data on muscle fibres' cross-sectional area, perimeter, diameter, and composition were analysed using two-way ANOVA, while pathological fibres were analysed using ANOVA. Pearson’s correlation was employed to examine MF microscopy associations with clinical features. Results revealed no significant differences in the outcome measures between the affected MF and MF from other sites, though they were significantly greater for type I fibres compared to type II fibres, irrespective of MF location. There were significantly more pathological fibres present in the affected MF (p<0.05). A weak but significant negative correlation was found between type I fibres and LBP clinical features, though no such correlations were observed for type IIA fibres. In conclusion, LDH primarily impacts the pathological status of the MF rather than fibre phenotype or size, and the severity of clinical features affects the size of type I fibres.
