Paraspinal muscles and intervertebral dysfunction: part two.
Level 5 - mechanism / opinion, no new human data
Narrative literature review evaluating proposed physiological mechanisms and theory without systematic quantitative synthesis.
PubMed 15195042 · doi:10.1016/j.jmpt.2004.04.008
What was done
The authors conducted a literature review searching MEDLINE and CINAHL databases, along with bibliographies of relevant articles and textbooks, using keywords related to paraspinal muscles, palpation, electromyography (EMG), spine, low back pain, myofascial tissue, tissue hardness, somatic dysfunction, and manipulation. The objective was to evaluate evidence supporting or refuting proposed biological mechanisms for altered paraspinal tissue texture associated with manipulable spinal lesions.
What was found
The abstract provides no quantitative figures or effect estimates. It reported that low back pain is associated with decreased paraspinal muscle activity, reduced strength, altered muscle fiber composition, and localized selective multifidus atrophy. The theory of simple segmental reflex paraspinal muscle contraction was not supported for low back pain. Instead, evidence pointed toward complex motor control alterations, specifically deep paraspinal muscle inhibition during dynamic tasks and involuntary guarding during static tasks. Evidence for the effects of spinal manipulation on paraspinal EMG activity was inconclusive, and direct evidence linking these physiological changes to clinically palpated tissue texture remains speculative.
Why it matters
This review challenges traditional mechanistic assumptions that manual palpation detects simple protective reflex spasms, indicating that palpable findings likely reflect more complex motor control dysfunction and structural muscle changes.
Limits
The review is narrative rather than systematic, with no reported study counts, quality assessment metrics, or quantitative synthesis in the abstract. The clinical relevance is constrained because direct empirical evidence linking observed electromyographic or structural muscle changes to manual palpatory findings is currently speculative.
Cited by
- context Muscle spasms often occur to provide artificial stability as a protective mechanism for an area of underlying muscular weakness.