Pain is one of the most common reasons for which people visit a physician. The Institute of Medicine reported that in 2011, about 100 million American adults suffered from chronic pain, incurring an annual cost of $560 to $635 billion. This number is almost four times greater than diagnosed diabetics and those with heart disease and almost ten times greater than the number of cancer victims, according to the American Academy of Pain Medicine. Although pain – acute and chronic – is often associated with tissue damage, such as a pinched nerve or a lesion, when there is no tissue damage involved, sometimes pain perception is mostly in the brain.
Howard Schubiner, M.D., who is the founder and director of the Mind Body Medicine Program at Providence Hospital, stated that pain stems from two primary causes: Tissue damage and nerve pathways. Having late stages of cancer or a broken arm are examples of pain stemming from tissue damage. However, pain coming from nerve pathways is less understood because there is usually no obvious structural damage or abnormalities in the tissues. Nerve pathway pain is a learned behavior in the nervous system. Examples include the way people walk, sign their name or swing a golf club. Pain is a nerve impulse in which the brain fires signals to the nerves that trigger pain sensations. Stress, fear and most emotional triggers can increase pain in nerve pathways, even though there is no tissue damage or structural problems.
However, most health care professionals still ascribe to the traditional teaching of pain as biomechanical, which implies that pain comes from structural abnormalities, such as poor posture and dysfunctional movement patterns. Current research, however, shows that there is little correlation between biomechanics and pain. In a 2008 systematic review published in Journal of Manipulative and Physiological Therapeutics, researchers Sanne Toftgaard Christensen and Jan Hartvigsen from the University of Southern Denmark reviewed 56 studies and found no strong evidence between spinal curve measurements and pain.
In another study published in The Clinical Journal of Pain, physiotherapist Lorimer Moseley and Paul Hodges, Ph.D., found that it is very possible that pain causes a change of posture rather than poor posture causes pain. The postural changes in the subjects are “not caused by pain interference but are likely to reflect development and adoption of an alternate postural adjustment strategy.” In other words, the postural deviation is an adaptation and response to pain in which the body finds a way to position itself to avoid the pain.
Even with more evidence suggesting that pain is not always a tissue damage or biomechanical problem, this pain model is still taught in most medical schools. Physical therapist Diane Jacobs said in an online interview that the current model is called the “bottom-up, Cartesian, ‘pain as an input to the brain’ model,'” which contrasts the biopsychosocial model. The latter model explains “pain as an output by the brain to conscious awareness, dependent not only on biological factors, but also an individual’s social experience, cognition, and present context.”
When she was asked why the structural model is taught instead of the biopsychosocial model, she replied, “Probably because it’s just easier than changing the curricula all around to accommodate an updated and more neuroscience-based conceptualization of pain.”
Although the current biomechanical model does not explain pain entirely, there are some instances where pain is not mostly in the brain. Physical therapist Tony Ingram, who practices in St. John, Newfoundland, wrote an article in Medbridge that advised fellow physical therapists to not ignore the structure entirely. He stated that current scanning technology, such as CAT scans and MRIs, may not be able to detect tissue damage on a microscopic level that could cause pain in the local area. Current scanning technology examines the body from a macro perspective. “For now, we certainly can’t take imaging findings too seriously. There are significant limitations to this type of research, and we should avoid jumping to conclusions – especially the idea that nothing in the low back matters in patients with chronic low back pain,” Ingram wrote.
Also, most scans require patients to remain stationary in a standing or lying down position, and these methods do not detect pain when they are in motion, such as bending forward, side to side or turning. “You also can’t MRI someone while they walk or do stairs,” Ingram wrote.
Meanwhile, healthcare professionals can utilize both the pain models to address their patients’ or clients’ pain issues instead of marrying themselves to one school of thought or philosophy. Licensed massage therapist Alice Sanvito, who practices in St. Louis, Missouri, suggests that pain education is one of the best tools to use in dealing with pain.
“When people understand how pain works, it takes a lot of the fear and anxiety out of it,” Sanvito explained in an interview. “Pain education is not a magic bullet to make the pain go away, but it can set the stage for turning the volume down on it and help people figure out successful coping strategies. Understanding that pain is generated by the brain does not mean that it’s ‘mostly in your brain.’ The experience of pain is very real. However, knowing how it works gives you clues about how to diminish it. It’s one of the most powerful tools we can give people in pain.”
By Nick Ng
Interview with Diane Jacobs, PT
Interview with Alice Sanvito, LMT
Journal of Manipulative and Physiological Therapeutics
The American Academy of Pain Medicine
Institute of Medicine Report
The Clinical Journal of Pain