Brain Areas Involved in Anticipation of Clinically Relevant Pain in Low Back Pain Populations With High Levels of Pain Behavior

The purpose of this study was to identify neural correlates of pain anticipation in people with non-specific low back pain (NSLBP) that correlated with pain-related distress and disability, thus providing evidence for mechanisms underlying pain behaviour in this population. Thirty NSLBP sufferers, with either high levels of pain behaviour (WS-H) or low levels (WS-L) based on Waddell Signs (WS), were scanned with functional Magnetic Resonance Imaging (fMRI) whilst a straight-leg raise (of the side deemed to cause moderate pain in the lower back) was performed. On each trial coloured stimuli were presented and used to indicate when the leg definitely would be raised (Green; 100% certainty), might be raised (Yellow; 50% certainty) or would definitely not be raised (Red; 100% certainty). In response to expected vs. unexpected pain the group difference in activation between WS-H and WS-L co-varied as a function of anxiety scores in right insula and pregenual anterior cingulate cortex and as a function of catastrophizing in prefrontal and parietal cortex and hippocampus. The results suggest NSLBP populations with the highest levels of pain-related distress are more likely to attend to and infer threat from innocuous cues, which may contribute to the maintenance of pain behaviour associated with some chronic pain states. Perspective: This article demonstrates a likely neural network for exacerbating pain anticipation in NSLBP contributing to high levels of pain behaviour in some people. This information could potentially help clinicians and patients to understand how anticipation of pain may contribute to patient pain and disability.