Human Studies

Low back pain is the largest contributor to disability worldwide. The role of body composition as a risk factor for back pain remains unclear. Our aim was to examine the relationship between fat mass and fat distribution on back pain intensity and disability using validated tools over 3 years.

Sciatica is a painful condition managed by a stepped care approach for most patients. Currently, there are no decision-making tools to guide matching care pathways for patients with sciatica without evidence of serious pathology, early in their presentation. This study sought to develop an algorithm to subgroup primary care patients with sciatica, for initial decision-making for matched care pathways, including fast-track referral to investigations and specialist spinal opinion.

Using opioids for acute pain can lead to long-term use and associated morbidity and mortality. Injury has been documented as a gateway to long-term opioid use in some populations, but data are limited for injured workers.

Neural responses to incentives are altered in chronic pain and by opioid use. To understand how opioid use modulates the neural response to reward/value in chronic pain, we compared brain functional magnetic resonance imaging (fMRI) responses to a monetary incentive delay (MID) task in patients with fibromyalgia taking opioids (N = 17), patients with fibromyalgia not taking opioids (N = 17), and healthy controls (N = 15). Both groups of patients with fibromyalgia taking and not taking opioids had similar levels of pain, psychological measures, and clinical symptoms. Neural responses in the nucleus accumbens to anticipated reward and non-loss outcomes did not differ from healthy controls in either fibromyalgia group. However, neural responses in the medial prefrontal cortex differed, such that patients with fibromyalgia not taking opioids demonstrated significantly altered responses to anticipated rewards and non-loss outcomes compared to healthy controls, but patients with fibromyalgia taking opioids did not. Despite limitations including the use of additional non-opioid medications by fibromyalgia patients taking opioids, these preliminary findings suggest relatively "normalized" neural responses to monetary incentives in chronic pain patients who take opioids versus those who do not.

Opioid-prescribing policies and guidelines aimed at reducing inappropriate opioid prescribing may lead physicians to stop prescribing opioids. Patients may thus encounter difficulties finding primary care practitioners willing to care for them if they take opioids.

Patient-Reported Outcome (PRO) instruments have been developed to evaluate pain management in daily practice; the PGIC is particularly recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT). The prospective non-interventional multicenter PRO-QURE study aimed at assessing correlations between PGIC and pain measurements and treatment effects in patients followed in French pain centers.

While several studies have found that chronic pain is characterized by increased cross-network connectivity between salience, sensorimotor, and default mode (DMN) networks, a large sample-size investigation allowing a more reliable evaluation of somatotopic specificity and subgroup analyses with linkage to clinical pain intensity has been lacking. We enrolled healthy adults and a large cohort of patients (N=181) suffering from chronic low back pain (cLBP). To specifically link brain connectivity with clinical pain intensity, patients were scanned at baseline and after performing physical maneuvers that exacerbated pain. Compared to healthy adults, cLBP patients demonstrated increased connectivity between the functionally-localized back representation in primary somatosensory cortex (S1back) and both salience and DMN networks. Pain exacerbation maneuvers increased S1back connectivity to salience network regions, but decreased connectivity to DMN, with greater pain intensity increase associated with greater shifts in these connectivity patterns. Furthermore, only in cLBP patients reporting high pain catastrophizing, DMN connectivity was increased to a cardinal node of the salience network, anterior insula cortex, which was correlated with increased post-maneuver pain in this cLBP subgroup. Hence, increased information transfer between salience processing regions, particularly anterior insula, and DMN may be strongly influenced by pain catastrophizing. Increased information transfer between salience network and S1 likely plays an important role in shifting nociceptive afference away from self-referential processing, re-allocating attentional focus and affective coding of nociceptive afference from specific body areas. These results demonstrate S1 somatotopic specificity for cross-network connectivity in encoding clinical back pain, and moderating influence of catastrophizing for DMN/insula connectivity.