Neuroimaging and Post-Operative Persistent Pain

FIGURE 1 Brain functional and anatomical properties predispose subjects to develop chronic pain. A. Strength of functional connectivity (extent of functional information shared between two brain regions) between medial prefrontal cortex (mPFC) and nucleus accumbens (NAc), designated as mPFC-NAc, distinguished between sub-acute back pain patients (SBP) who one year later persist (SBPp) or recover (SBPr). This group difference is sustained as it is preserved at four different brain scans (visits 1–4), performed at entry into study (visit 1), and at 3, 6, and 12 months (visits 2–4) from start of back pain. The right panel depicts receiver operator curve (ROC) for differentiating between SBPp and SBPr, based on mPFC-NAc values at time of entry into the study, for predicting future subgroups at 3, 6, and 12 months. D-values are overall accuracy of prediction and increases at longer times from initiation of back pain. Data adapted from [5, 23]. B. Brain white matter myelination and branching properties, as identified using diffusion tensor imaging and calculating local fractional anisotropy (FA), also distinguishes between SBPp and SBPr (red blobs on the green-colored white matter skeleton). FA value differences between the two groups are also sustained at all four scan times. Moreover, FA at time of entry into the study highly accurately differentiates the two groups at all three future times.

Overall, the general proposal put forward is that brain properties do play a critical role in post-operative persistent pain. However, the extent of this involvement and the specific circuitry underlying it is most likely distinct for different surgical procedures. We now know how to perform such studies and we have the tools with which to do them. Therefore, it is both scientifically and clinically urgent that we begin untangling these parameters, as the obtained results most likely will dramatically change our notions and thus clinical practice.

REFERENCES

1. Apkarian AV, Bushnell MC, Treede RD, Zubieta JK. Human brain mechanisms of pain perception and regulation in health and disease. Eur J Pain 2005;9(4):463–484.

2. Apkarian AV, Hashmi JA, Baliki MN. Pain and the brain: Specificity and plasticity of the brain in clinical chronic pain. Pain 2011;152(3):s49–s64.

3. Baliki MN, Chialvo DR, Geha PY, et al. Chronic pain and the emotional brain: specific brain activity associated with spontaneous fluctuations of intensity of chronic back pain. J Neurosci 2006;26(47):12165–12173.

4. Baliki MN, Geha PY, Apkarian AV, Chialvo DR. Beyond feeling: chronic pain hurts the brain, disrupting the default-mode network dynamics. J Neurosci 2008;28(6):1398–1403.

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