A vulnerability to chronic pain and its interrelationship with resistance to analgesia.

Abstract

This scientific commentary refers to ‘Corticolimbic anatomical characteristics predetermine risk for chronic pain’, by Vachon-Presseau et al. (doi:10.1093/brain/aww100). Chronic pain is a major medical health problem (IOM, 2011). The socio-economic burden is alarming, yet—to date—we have few effective treatments. A better understanding of the underlying biology leading to the development, maintenance and exacerbation of chronic pain is desperately needed to improve this bleak situation. Progress is being made, but a major unresolved question remains: ‘Why me?’ Several examples in the clinical pain literature demonstrate that only a proportion of patients with a particular disease or injury go on to develop chronic pain (see Table 1 in Denk et al. , 2014). For example, diabetic neuropathy is a relatively common condition but only a minority of patients report symptoms of pain. As with many areas of chronic neurological disease, questions about vulnerability and resilience to developing chronic pain are now being asked. In this issue of Brain , Vachon-Presseau and co-workers propose answers based on an extensive longitudinal analysis of patients with subacute pain that either resolves or becomes chronic (Vachon-Presseau et al. , 2016). Epidemiological studies of patient cohorts (e.g. low back pain) and innovative studies linking presurgical assessments to pain outcomes post-surgery have identified several risk factors that predispose an individual towards chronic pain (Kehlet et al. , 2006; Balague et al. , 2012; Denk et al. , 2014). Gender, age and genetic make-up are relevant. Additional risk factors relate to an individual’s personality and psychosocial environment alongside previous pain history, stress and depressive illness; these all conspire to negatively affect long-term pain outcome. Intriguingly, these factors lend themselves to a possible brain-based explanation for why some patients are more vulnerable (or less resilient) to developing chronic pain. Observations from preclinical and human neuroimaging …