Paraspinal muscle pathophysiology associated with low back pain and spine degenerative disorders

Abstract

Low back pain disorders affect more than 80% of adults in their lifetime and are the leading cause of global disability. The muscles attaching to the spine (ie, paraspinal muscles) are critical for proper spine health and play a crucial role in the functioning of the spine and whole body; however, reports of muscle dysfunction and insufficiency in chronic LBP (CLBP) patients are common. This article presents a review of the current understanding of the relationship between paraspinal muscle pathophysiology and spine‐related disorders. Human literature demonstrates a clear association between altered muscle structure/function, most notably fatty infiltration and fibrosis, and low back pain disorders; other associations, including muscle cell atrophy and fiber type changes, are less clear. Animal literature then provides some mechanistic insight into the complex relationships, including initiating factors and time courses, between the spine and spine muscles under pathological conditions. It is apparent that spine pathology can directly lead to changes in the paraspinal muscle structure, function, and biology. It also appears that changes to the muscle structure and function can directly lead to changes in the spine (eg, deformity); however, this relationship is less well studied. Future work must focus on providing insight into possible mechanisms that regulate spine and paraspinal muscle health, as well as probing how muscle degeneration/dysfunction might be an initiating factor in the progression of spine pathology.

The Relationship Between Degeneration and Asymmetry of the Lumbar Multifidus and Erector Spinae Muscles in Patients with Lumbar Disc Herniation with and Without Root Compression

“…In the current study, the CSA and TCSA values of males were found to be higher than those of females. Previous studies have also shown greater CSA and higher density of paraspinal muscles in males than in females [17,19,27,61,71,72]. The current study results were consistent with literature.…”

“…The paraspinal muscles are of critical importance for spinal health. Parspinal muscle dysfunction and failure is common in patients with low back pain [19]. LDH and other causes of low back pain, and many spine pathologies cause changes in the paraspinal muscles.…”

“…These changes include an increase in fat and connective tissue in the muscle, bre type changes, distorted cell populations, altered gene epression, low muscle resistance, low muscle strength, and muscle atrophy [20][21][22][23][24][25][26][27]. These ndings are seen in parallel with denervation and re-innervation of the parspinal muscles in disc herniation and nerve root compression [11,19,28].…”

“…The role of the paraspinal muscles in low back pain and LDH remains uncertain. It is still largely unknown whether paraspinal muscle atrophy is a cause or a result of various pathological processes in the lumbar spine [19,43]. In a study conducted on rats by Maas et al, the lumbar MF was completely removed bilaterally and no problems were observed in the disc or nucleus pulposa.…”

Correlation between the fatty infiltration of paraspinal muscles and disc degeneration and the underlying mechanism

“…These muscles play a key role in maintaining lumbar segment stability and dynamic regulation; they can maintain the posture and restrict excessive intervertebral movement [ 8 , 9 ]. Previous studies have observed structural remodeling of paraspinal muscles in LDD, including fatty infiltration, asymmetry, and decreased size [ 2 , 10 , 11 ]. Among them, fatty infiltration of paraspinal muscles is closely related to high-intensity pain/disability and structural abnormalities in the lumbar spine [ 6 , 12 – 15 ].…”