What exactly is happening when a chiropractic adjustment is made in order to correct a vertebral subluxation complex (VSC)? Great question. One thing we know for absolute certain is that the adjustment results in neurological and biomechanical change in the spine and the body as a whole. To what extent and how far reaching that change is continues to be debated, but recent research has revealed a great deal.
“This study suggests that cervical spine manipulation may alter cortical somatosensory processing and sensorimotor integration. These findings may help to elucidate the mechanisms responsible for the effective relief of pain and restoration of functional ability documented following spinal manipulation treatment.”
-Haavik-Taylor H, Murphy B. “Cervical spine manipulation alters sensorimotor integration: a somatosensory evoked potential study.” Clin Neurophysiol. 2007 Feb;118(2):391-402. Epub 2006 Nov 29.
“Spinal manipulative therapy (SMT) acts on the various components of the vertebral motion segment. SMT distracts the facet joints, with faster separation when a cracking sound is heard. Intradiscal pressure may decrease briefly. Forceful stretching of the paraspinal muscles occurs, which induces relaxation via mechanisms that remain to be fully elucidated. Finally, SMT probably has an inherent analgesic effect independent from effects on the spinal lesion.”
-Maigne JY, Vautravers P. “Mechanism of action of spinal manipulative therapy.” Joint Bone Spine. 2003 Sep;70(5):336-41.
“The evidence suggests that effects of spinal manipulative therapy is primarily neurophysiologic, most likely mediated by intense stimulation of large myelinated fibers in the capsular and/or periarticular tissues. Basic science also demonstrates that large fiber stimulation can modulate dorsal horn excitability by inducing segmental inhibitory mechanisms. The phenomenon of dorsal horn excitability, also referred to as central facilitation or sensitization, is pivotal to the contemporary chiropractic paradigm.”
-Srbely, John. “Chiropractic Science: A Contemporary Neurophysiologic Paradigm.” JCCA 2010;54(3):144-146.
“SMT(spinal manipulative therapy)-treated subjects show a time-dependent attenuation of LPS (lipopolysaccharide)-induced production of the inflammatory cytokines unrelated to systemic levels of SP (substance P). This suggests SMT-related down-regulation of inflammatory-type responses via a central yet unknown mechanism.”
-Teodorczyk-Injeyan JA, Injeyan HS, Ruegg R. “Spinal manipulative therapy reduces inflammatory cytokines but not substance P production in normal subjects.” J Manipulative Physiol Ther. 2006 Jan;29(1):14-21.
As a side note, the above quote states “via a central yet unknown mechanism.” However, read the study at the top left of this page as it explains one of the central mechanisms now identified.