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Functional imaging in chronic pain

Functional imaging in chronic pain. Marwan N Baliki Ph.D. Northwestern University Department of Physiology Apkarian pain and emotion Lab. Outline. Brain imaging in acute and chronic pain 1. Cortical mechanisms of acute and chronic pain

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Functional imaging in chronic pain

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  1. Functional imaging in chronic pain Marwan N Baliki Ph.D. Northwestern University Department of Physiology Apkarian pain and emotion Lab

  2. Outline • Brain imaging in acute and chronic pain • 1. Cortical mechanisms of acute and chronic pain • 2. Impact of chronic pain on brain structure • Brain functional/structural changes associated with the transition of pain form acute to chronic state Using functional imaging, we can identify suitable brain marker that can predict the onset of chronic pain after injury

  3. Pain: general definition • Pain is one of the most important functions of the nervous system and provides information about the presence or threat of injury. “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” • Pain is a complex perception: • Sensory properties – quality, location, intensity • Affective properties - desire to avoid harm • Cognitive properties – appraisal of experience • Multiple distinct states : • Acute – transient (seconds to minutes) • Chronic – maladaptive (can last a lifetime)

  4. Spinal cord pathways of pain

  5. Brain activity for acute pain

  6. Spontaneous pain rating in chronic back pain (CBP)

  7. Brain activity for CBP Healthy (acute thermal pain) CBP (acute thermal pain) CBP (spontaneous pain)

  8. Different clinical pain conditions show distinct brain activity

  9. Conclusions from functional studies • Brain activity for chronic pain ≠ acute pain • Chronic pain tends to activate limbic regions (amygdala, striatum and hippocampus) • Brain activity for clinical pain is specific for the clinical pain type

  10. Chronic pain & brain structure

  11. Global gray matter changes in chronic pain CSF Gray White 2.5 cc/year of aging 1.5 cc/year of pain

  12. Regional analyses show decreased gray matter in specific regions CRPS Tension headache Fibromyalgia (Geha et al 2008) (Kuchinad et al 2007) (Schmidt-Wilcke et al 2005)

  13. Conclusions from structural studies • Chronic pain is associated with global and local changes in gray matter density • Morphological changes are specific for chronic pain type and reflect clinical properties of the condition • Evidence for reversal after cessation of pain

  14. Chronic pain as emotional learning and memory • Pain chronification is not simply a consequence of the pain being experienced repeatedly over a sustained time period. • Cortico-striataland cortrico-limbic brain circuitry may be directly involved in the development and maintenance of chronic pain. Apkarian et al 2010

  15. From acute to chronic pain (the clinical dilemma) Sub-acute pain Acute pain Chronic pain A single intense episode of back pain lasting 4-16 weeks and no prior back pain for at least one year • Only a fraction (~ 5%) of subjects who experience an acute painful injury continue to develop chronic pain • No consistent behavioral, psychological or neurobiological factors can predict transition to chronic pain To localize brain regions showing anatomical and functional changes

  16. Why examine back pain ? • CBP is one of the 3 most common reasons for healthcare visits • Not more than 10-15% of such patients show associated physical changes • There are no scientifically validated treatments • It is associated with spontaneous pain (main reason for seeking medical care)

  17. Study design Persisting (SBPp) (no change in pain) SBP Recovering (SBPr) (>30% decrease in pain) Consequences Predictors

  18. Clinical pain parameters

  19. Longitudinal changes in gray matter density All subjects SBPp only • SBPp and SBPr did not exhibit gray matter density differences at visit 1

  20. Differences in functional connectivity at visit 1 Right insula (visit 1) Right NAc (visit 1)

  21. mPFC – NAc connectivity predicts transition to chronic pain Prediction convert the visit 1 mPFC-NAc functional connectivity into quartiles (each category defined by z(r) change of 0.17)

  22. Conclusions from longitudinal study • Persistent pain is associated with early mPFC-NAc coupling that is sustained over one year • mPFC – NAc functional connectivity may be a suitable marker for the development of chronic pain • Anatomical and functional changes were observed as early as 16 weeks after injury • Interventions should not only target the classical pain pathways, but also brain regions involved in motivation and emotion processing

  23. Acknowledgments Souraya Torbay Marivi Centeno Ali Mansour Kristina Hermmann Amelia Mutso Elle Parks A Vania Apkarian Javeria Hashmi Lejian Huang Alex Baria Bogdan Petre Sara Berger

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