Pain Processing in the Human Nervous System: A Selective Review of Nociceptive and Biobehavioral Pathways
Pain is a biopsychosocial experience that goes well beyond mere nociception. In this regard, identification of the physical pathology at the site of injury is necessary but not sufficient to explicate the complex process by which somatosensory information is transformed into the physiologic, cognitive, affective, and behavioral response labeled as pain.
In the case of chronic low back pain, the magnitude of tissue damage may be out of proportion to the reported pain experience; there may be no remaining structural impairment; and physical signs that have a predominantly nonorganic basis are likely to be present.
Pain, whether linked with injured tissue, inflammation, or functional impairment, is mediated by processing in the nervous system. In this sense, all pain is physical. Yet regardless of its source, pain may result in hypervigilance, threat appraisals, emotional reactions, and avoidant behavior. So in this sense, all pain is psychological.
Our nomenclature and nosology struggle to categorize the pain experience, but in the brain, all such categories are moot. Pain is fundamentally and quintessentially a psychophysiological phenomenon.
Garland, E.L., Pain Processing in the Human Nervous System. Primary Care: Clinics in Office Practice. Sept. 2012, V 39, Issue 3, pgs 561-571. https://doi.org/10.1016/j.pop.2012.06.013.