Pain imaging in health and disease - how far have we come

Schweinhardt P, Bushnell MC Pain imaging in health and disease - how far have we come ? J Clin Invest 2010;120(11):3788-3797

  • pain matrix
    • S1,S2,ACC,IC,PFC,thalamus,basal ganglia, and cerebellum
  • fMRI methodology
    • BOLD (blood oxygenation level-dependent)
    • ASL (arterial spin labeling)
  • DTI (diffusion tensor imaging)
  • mechanism underlying psychological modulation of pain
    • attention alters nociceptive responsiveness
    • emotions alters nociceptive responsiveness
      • These studies show that mood state affects pain-evoked activity, particularly in limbic regions of the brain such as the ACC, frontal cortex, and hippocampus.
    • exploring brain circuits involved in attentional and emotional modulation
    • Brain responses during anticipation of pain
  • Chronic pain patients have enhanced pain processing
    • there is evidence that patients with chronic pain syndroms process acute pain differently than do healthy people.
  • Do chronic pain patients have altered supraspinal pain modulation?
    • Change in spatial representation
    • Decreased inhibition versus increased facilitation
    • brainstem facilitatory mechanisms might play a role for neuropathic symptoms in a disorder that has been traditionally considered a nociceptive condition.
    • The medial PFC appears to be an important site of supra-spinal pain facilitation.
    • medial PFC was indeed involved in enhancing clinical pain.
    • PAG also plays a role in pain facilitation, and it is important to point out that fMRI cannot differentiate between activation in brainstem facilitatory and inhibitory circuits.
      • Diffuse noxious inhibitory control (DNIC)
  • structural brain alterations in chronic pain patients
    • individuals who suffer from long-term pain not only process pain differently, but also present with structural brain changes.
    • grey matter decreases are a consequence of living with pain, at least these instances.
  • cerebral biochemical alteration associated with chronic pain
    • a preliminary study of 20 healthy elderly subjects with varying levels of chronic pain found pain severity to be related to lower NAA levels in the hippocampus as well as to reduced hippocampal volumes