Chronic Low Back Pain Characterized by Emotional Circuits in the Brain

Kristen Sparrow • January 19, 2014

San Francisco Acupuncture for Back PainThis post is for background purposes.  There has been interesting work done in the Acupuncture Research community looking at which regions of the brain light up during acupuncture.  I don’t claim to be an expert in any way on this topic, but I think it might be key to understanding acupuncture’s mechanisms and, perhaps, ways to make it better and more effective. Though fMRI is an incredible tool for study, I don’t think it’s feasible for routine use in evaluating patients.  Too expensive. That’s why I’m always improving the heart rate variability analysis.
(I spoke to Apkarian once at a Pain Conference in Barcelona.  He gave a talk on patient assessment ratings of pain over short time intervals using a finger strain gauge (if I recall correctly.)  He showed that the pain assessment followed a fractal pattern.  Looking at his tracings, I spent a fair amount of time using fractal analysis of the heart rate variability tracings I was collecting in an attempt to get a more nuanced look.  Alas, I never could get any meaningful data.)

Brain. 2013 Sep;136(Pt 9):2751-68.
Shape shifting pain: chronification of back pain shifts brain representation from nociceptive to emotional circuits. Hashmi JA, Baliki MN, Huang L, Baria AT, Torbey S, Hermann KM, Schnitzer TJ, Apkarian AV.
Chronic pain conditions are associated with abnormalities in brain structure and function. Moreover, some studies indicate that brain activity related to the subjective perception of chronic pain may be distinct from activity for acute pain. However, the latter are based on observations from cross-sectional studies. How brain activity reorganizes with transition from acute to chronic pain has remained unexplored. Here we study this transition by examining brain activity for rating fluctuations of back pain magnitude. First we compared back pain-related brain activity between subjects who have had the condition for ∼2 months with no prior history of back pain for 1 year (early, acute/subacute back pain group, n = 94), to subjects who have lived with back pain for >10 years (chronic back pain group, n = 59). In a subset of subacute back pain patients, we followed brain activity for back pain longitudinally over a 1-year period, and compared brain activity between those who recover (recovered acute/sub-acute back pain group, n = 19) and those in which the back pain persists (persistent acute/sub-acute back pain group, n = 20; based on a 20% decrease in intensity of back pain in 1 year). We report results in relation to meta-analytic probabilistic maps related to the terms pain, emotion, and reward (each map is based on >200 brain imaging studies, derived from neurosynth.org). We observed that brain activity for back pain in the early, acute/subacute back pain group is limited to regions involved in acute pain, whereas in the chronic back pain group, activity is confined to emotion-related circuitry. Reward circuitry was equally represented in both groups. In the recovered acute/subacute back pain group, brain activity diminished in time, whereas in the persistent acute/subacute back pain group, activity diminished in acute pain regions, increased in emotion-related circuitry, and remained unchanged in reward circuitry. The results demonstrate that brain representation for a constant percept, back pain, can undergo large-scale shifts in brain activity with the transition to chronic pain. These observations challenge long-standing theoretical concepts regarding brain and mind relationships, as well as provide important novel insights regarding definitions and mechanisms of chronic pain.