From psychological tests, the researchers found that pain is actually more accurately associated with the patient's state of mind -- with depression and poor coping skills often being a better predictor of back pain than disc damage. The researchers therefore cautioned that treating a patient for emotional and perceptual concerns may be more beneficial in reducing lower back pain than the more standard invasive, costly, and oftentimes unsuccessful back fusion surgery option.
Carragee said that pre-existing psychological problems seem to have a clear relationship with both the onset of lower back pain and the manner in which it is managed.
"Those people who suffered from depression or an over-reaction to pain or fear of being hurt reported a lot more pain," he noted. "If someone has a tendency to hyperbolize whatever problems they have -- like headaches -- when they do get a back pain episode they really cope with it very badly. There are some people who, when they hurt, will try and stay in as good shape as possible and in most of those people the pain will go away. And that's the normal course of back pain for 85% of the people. It will go away in a matter of a few weeks. But for the others, they get into a real cycle of getting more disabled, getting more pain, getting more discouraged, and 2 years go by and those people can become a real wreck."
Carragee suggested that for some people addressing the psychological dimension could help reduce the pain and quicken relief.
"The best thing for them and their physicians is to work towards taking away the stigma of their having a serious pathology in their back," he said. "It would be easier to help them and get them going. It's mentally hard to get someone to rehabilitate if they think they have a serious mechanical problem in their back. And if people are depressed, confronting whatever those issues are head-on could help as well."
Our perceived sensory experiences are heavily shaped by interactions between our expectations and incoming sensory information. As the magnitude of expected pain increases, activation increases in the thalamus, insula, prefrontal cortex, anterior cingulate cortex (ACC) and other brain regions. Pain-intensity related brain activation are identifiable in a widely distributed set of brain regions but overlap partially with expectation-related activation in regions, including the anterior insula and ACC. When expected pain is manipulated, expectations of decreased pain powerfully reduced both the perceived experience of pain and the activation of pain-related brain regions, such as the primary somatosensory cortex, insular cortex, and ACC. These results confirm that a mental representation of an impending sensory event can significantly shape neural processes that underlie the formulation of the actual sensory experience and provide insight as to how positive expectations diminish the severity of chronic disease states.12
Chronic pain can be viewed as a state of continuous learning coupled with reduced opportunity for forgetting]13=15. Many studies illustrate the potency of painful events to induce learning, the majority of which pair pain (electrical shock) with a variety of other previously unassociated events. These studies repeatedly show that single painful stimuli are learned and remembered for weeks and months. Once the associated learning occurs, the extinction of this association requires repeated exposure to the conditioned stimulus in the absence of the painful event. As chronic pain is fundamentally a state of continuous presence of pain, we can then conclude that it is also a state of continuous acquisition of associations with random events surrounding the organism, especially at time points when the pain is high. Moreover, as the pain remains unremitting, the organism does not have the opportunity of extinguishing these random associations, which requires frequent exposure to the same environment in the absence of pain. The contradiction between the subject's conscious knowledge that the pain is not associated with the environment and the brain circuitry that continuously make such associations may be the core cognitive/emotional source of the suffering that chronic pain patients experience. Information about pain accesses the cortex through multiple pathways and not just by the spinothalamic projection, which is the known pain pathway. Even within the spinothalamic system medial thalamic cortical projections access large portions of the frontal cortex targeting mainly superficial layers]16. This pathway is a reticulo-thalamocortical network that relays widespread pain information to widespread cortical regions and most likely provides modulatory influences on large prefrontal cortical processes.
Other nociceptive pathways such as the parabrachialamygdala projections, spinal basal ganglia projections, spinal hypothalamic and spinal prefrontal projections17-20 and other monosynaptic and polysynaptic spinal-reticular-cortical projections provide ample opportunities for pain processing accessing various cortical circuitry and modulating such circuitry as a function of a continuous barrage of inputs associated with chronic pain. Thus, continuous input to the brain both reorganizes memories and their associations, and reorganizes motivational and memory consolidation properties of the limbic cortex, which is the emotional center of the brain. The functional brain imaging studies for chronic pain point to the recurring theme that chronic pain conditions engage preferentially medial prefrontal cortical areas as well as subcortical limbic regions, especially portions of the dorsal and ventral basal ganglia], amygdala, and hippocampus.
