Persistent back pain has both peripheral and central components.
Questions whether spinal imaging is diagnostic of for general back pain, rather than simply a useful filter for specific conditions.
If spinal imaging is a checkpoint before proceeding to surgery. One might expect that if the checkpoint has a failure rate, this would be reflected in the subsequent surgery. Suggests this is true.
Market needs
- Spine care costs are $100 billion in US annually
- 80000 spine procedures fail annually
- 1 in 5 patients return for a subsequent operation
Types of pain
- Nociceptive pain: short lived
- Inflammatory pain: involves cytokines
- Neuropathic pain: damage to nerve
- Chronic pain: persists beyond the original insult
Clifford Woolf
Regions of the brain that respond to acute pain are different from those that respond to chronic pain
Nociceptive insults mainly activate sensory regions. Chronic pain activates prefrontal cortex and limbic regions.
Chronic pain sufferers lose 5-10 percent of their grey matter in hippocampus and prefrontal cortex
Limits of what is known in the literature: do not yet understand causality - does the ability for brain reorganization predispose one to chronic pain, or is it caused by the chronic pain?
Lab directions
Woolf is taking a genetic approach. Understand families with inherited pain disorders. Try to get insight as into mechanisms that may translate to wildtype chronic pain situations.
Also trying the “organoid” approach. Reprogram biopsied skin cells into nerve cells. Create an in vitro assay to study and manipulate their activity.
Catechol-O-methyltransferase (CMOT)
Variants that decrease the efficacy of the enzyme result in excess dopamine in the synapse. Emotion / pain-sensitive.
Opioid-induced hyperalgesia
long-term use of opioid pain medication can result in hightened pain responses
Theories for chronic pain mechanisms
Gain adapation at the peripheral to central synapse
A brain circuit has been conditioned to activate. learned pain?
Exploratory therapies for chronic pain such as cognitive behavioral therapy. this is analogous to immunotherapy. provide the feared stimuli at graded intensities, work up psychological resistance to pain