Scientists have uncovered why many treatments are ineffective in addressing chronic lower back pain.
It seems the affliction wires deeply into the human psyche – turning on brain triggers normally shut off by pain.
The World Health Organization says that lower back pain is the single leading cause of disability worldwide.
While pain signals originate in the brain, scientists have been struggling to fully understand the specific neural circuitry that sparks movement-based pain.
Researchers at UC San Diego School of Medicine say they have now found that the brain region’s Default Mode Network (DMN) is turned on when patients experience sudden back pain brought on by movement.
This network is generally associated with self-awareness and memories and typically shuts down during “ordinary” acute pain.
In a study published in the British Journal of Anaesthesia, the researchers outlined the first evidence that the experience of chronic pain is not just a sensation, but is deeply embedded in the human sense of self.
They found that when a patient experienced intense pain during a leg raise test, greater activity was observed in the brain’s sensory and motor regions.
“Participants who suffered from more severe chronic back pain had stronger connections between the DMN and the primary somatosensory cortex, the area of the brain that processes sensations from the back,” the study report said.
“An increase in heart rate during the leg raise test was a reliable indicator of how intense the pain flare was.
“In every pain study, when you’re experiencing pain, the DMN deactivates. What we show for the first time ever is that when you have a pain flare, it turns on instead. You start to identify the experience with who you are.”
In contrast to the lower back findings, when the participants were subjected to painful heat, their DMN shut down, which was the brain’s usual response to acute pain.
The shutdown is to allow the brain to focus entirely on the external threat.
The study report said: “In essence…the brain (in this new study) is maladaptively coupling the physical pain with a deep, internal sense of self.
“The moment-to-moment experience is contaminated not only by the feeling of pain, but by the anticipation of it and recovery from it. It’s contaminated by past experiences like embarrassment about not being able to participate in normal activities and fear of movement when trying to avoid the pain.”
Director of the Pain Health and Mindfulness Laboratory at UC San Diego School of Medicine, Professor Fadel Zeidan, said current pain medicine was fixated on ridding patients of their pain symptoms, but that was not the source of chronic pain.
The new research points to different treatments like mindfulness meditation and helping patients separate the physical experience of chronic pain from their identity.
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