Is low intensity exercise sufficient to induce exercise-induced pain threshold modulation in people with persistent pain?

OBJECTIVES: We investigated whether a 12-min walk test (12MWT) yielded exercise-induced pain threshold modulation (EIPM) within people with persistent pain and whether baseline self-report and pain sensitivity measures differed according to these responses. DESIGN: Cross-sectional study. METHODS: Two cohorts (tertiary/community) (n = 88) with persistent pain underwent pressure pain threshold (PPT) testing before and after a 12MWT to determine exercise-induced pain threshold modulation responses. Baseline self-report (pain severity, pain distribution, psychological distress, sleep) and baseline widespread pain sensitivity (WPS) (high/low) were recorded. Within and between-group differences were analysed using paired t-tests and repeated measure analyses of covariance. Individual EIPM responses were categorised as hyperalgesic, no change and hypoalgesic responses. Differences in baseline self-report and pain sensitivity measures between EIPM categories were investigated. RESULTS: No significant within- or between-group differences in PPT following the 12MWT were detected (p > 0.05). Individual responses showed that up to 30% of the community and 44% of the tertiary cohort demonstrated >20% change in PPT (in either direction). Significant differences were shown in pain distribution (p = 0.002) and baseline WPS (p = 0.001) between people with hyperalgesic, no change, hypoalgesic responses. People with 4-5 pain regions were more likely hyperalgesic (χ2 = 9.0, p = 0.003); people with low baseline WPS were more likely to demonstrate no change (p = 0.002). CONCLUSION: Low or self-selected intensity exercise was insufficient to induce exercise-induced pain modulation at group level. Individual responses were variable with pain distribution and baseline WPS differing between responses. Future research could evaluate responses and associated factors in larger samples with high baseline pain sensitivity specifically.

Health and service needs, priorities and initiatives of primary health networks related to chronic pain.

BACKGROUND: Chronic pain is a major and growing public health issue. Multidisciplinary tertiary pain services cannot meet patient demand and greater involvement of primary care is needed. The aims of this study were to understand the needs and priorities of Australian primary health networks (PHNs) related to the management and secondary prevention of chronic pain; map current PHN chronic pain initiatives and identify gaps; highlight key enablers to implementation; and highlight solutions identified by PHNs to increase capacity to commission initiatives. METHODS: Mixed methods were used, including: a review of PHN needs assessments; and consultation with PHN executive-level staff and program managers from 27 out of the 28 PHNs, and the WA Primary Health Alliance (WAPHA - a state alliance between three Western Australian PHNs) via telephone interviews, online surveys, a workshop, a deliberative dialogue and email consultation. RESULTS: Chronic pain was identified as a health and/or service need by approximately half of PHNs. Barriers for PHNs to identifying chronic pain as a need or priority are highlighted. Gaps identified by the mapping included: initiatives related to the secondary prevention of chronic pain (post-surgery or post-injury), digitally enabled consumer and health professional chronic pain initiatives, and chronic pain initiatives for specific populations groups such as Aboriginal and Torres Strait Islander people. Among existing PHN practice, two exemplar evidence-based initiatives suitable for scale-up across PHNs in Australia were identified: multidisciplinary community-based pain programs, and an online health professional capacity-building initiative, Project ECHO (chronic pain). Solutions identified by PHNs to increase capacity to commission initiatives included: co-funding initiatives across different PHN funding streams, collaborative initiatives between PHNs, and co-commissioning with government and non-government partners. CONCLUSIONS: Chronic pain has been classified as a disease in itself through the World Health Organization. PHNs recognising chronic pain as a distinct condition in PHN needs analysis and data collection would lead to more dedicated funding. PHNs could do more to improve the secondary prevention and management of chronic pain. A self-identified need for greater collaboration across PHNs and co-commissioning with local and state governments and non-government partners would help to build PHN capacity.

Primary care initiatives focused on the secondary prevention and management of chronic pain: a scoping review of the Australian literature.

The aim of this scoping review was to identify initiatives focused on the secondary prevention and management of chronic pain in Australian primary care to understand options available to Primary Health Networks and to identify evidence gaps. The Medline, EMBASE, Cumulative Index to Nursing and Allied Health Literature and Cochrane databases, as well as relevant websites, were searched for eligible records published from 2007 to 2018. Initiative characteristics and outcomes evaluated were extracted and synthesised. In all, 84 initiatives from 167 published and grey literature records were identified, including: (1) consumer initiatives that aimed to improve access to multidisciplinary care, health literacy and care navigation (n=56); (2) health professional capacity building initiatives that aimed to ensure health professionals are skilled and provide best-practice evidence-based care (n=21); and (3) quality improvement and health system support initiatives (n=7). Evidence gaps were found relating to initiatives addressing the secondary prevention of chronic pain, those targeting vulnerable and regional populations, health professional capacity building initiatives for all primary health care providers and quality improvement and system support initiatives. Addressing evidence gaps related to effectiveness, cost-effectiveness and implementation should be the focus for future chronic pain initiatives in primary care settings.

Physiotherapy informed by Acceptance and Commitment Therapy (PACT): protocol for a randomised controlled trial of PACT versus usual physiotherapy care for adults with chronic low back pain.

INTRODUCTION: Chronic low back pain (CLBP) is a common condition and source of significant suffering, disability and healthcare costs. Current physiotherapy treatment is moderately effective. Combining theory-based psychological methods with physiotherapy could improve outcomes for people with CLBP. The primary aim of this randomised controlled trial (RCT) is to evaluate the efficacy of Physiotherapy informed by Acceptance and Commitment Therapy (PACT) on functioning in patients with CLBP. METHODS AND ANALYSIS: The PACT trial is a two-armed, parallel-group, multicentre RCT to assess the efficacy of PACT in comparison with usual physiotherapy care (UC). 240 patients referred to physiotherapy with CLBP will be recruited from three National Health Service (NHS) hospitals trusts. Inclusion criteria are: age ≥18 years, CLBP ≥12-week duration, scoring ≥3 points on the Roland-Morris Disability Questionnaire (RMDQ) and adequate understanding of spoken and written English to participate. Patients will be randomised to PACT or UC (120 per arm stratified by centre) by an independent randomisation service and followed up at 3 and 12 months post randomisation. The sample size of 240 will provide adequate power to detect a standardised mean difference of 0.40 in the primary outcome (RMDQ; 5% significance, 80% power) assuming attrition of 20%. Analysis will be by intention to treat conducted by the trial statistician, blind to treatment group, following a prespecified analysis plan. Estimates of treatment effect at the follow-up assessments will use an intention-to-treat framework, implemented using a linear mixed-effects model. ETHICS AND DISSEMINATION: This trial has full ethical approval (14/SC/0277). It will be disseminated via peer-reviewed publications and conference presentations. The results will enable clinicians, patients and health service managers to make informed decisions regarding the efficacy of PACT for patients with CLBP. TRIAL REGISTRATION NUMBER: ISRCTN95392287; Pre-results.

Pharmacologic modulation of hand pain in osteoarthritis: a double-blind placebo-controlled functional magnetic resonance imaging study using naproxen.

OBJECTIVE: In an attempt to shed light on management of chronic pain conditions, there has long been a desire to complement behavioral measures of pain perception with measures of underlying brain mechanisms. Using functional magnetic resonance imaging (fMRI), we undertook this study to investigate changes in brain activity following the administration of naproxen or placebo in patients with pain related to osteoarthritis (OA) of the carpometacarpal (CMC) joint. METHODS: A placebo-controlled, double-blind, 2-period crossover study was performed in 19 individuals with painful OA of the CMC joint of the right hand. Following placebo or naproxen treatment periods, a functionally relevant task was performed, and behavioral measures of the pain experience were collected in identical fMRI examinations. Voxelwise and a priori region of interest analyses were performed to detect between-period differences in brain activity. RESULTS: Significant reductions in brain activity following treatment with naproxen, compared to placebo, were observed in brain regions commonly associated with pain perception, including the bilateral primary somatosensory cortex, thalamus, and amygdala. Significant relationships between changes in perceived pain intensity and changes in brain activity were also observed in brain regions previously associated with pain intensity. CONCLUSION: This study demonstrates the sensitivity of fMRI to detect the mechanisms underlying treatments of known efficacy. The data illustrate the enticing potential of fMRI as an adjunct to self-report for detecting early signals of efficacy of novel therapies, both pharmacologic and nonpharmacologic, in small numbers of individuals with persistent pain.

Alterations in resting-state regional cerebral blood flow demonstrate ongoing pain in osteoarthritis: An arterial spin-labeled magnetic resonance imaging study.

OBJECTIVE: Increasing evidence suggests a central nervous system (CNS) component underpinning persistent pain disease states. This study was undertaken to determine regional cerebral blood flow (rCBF) changes representing ongoing pain experienced by patients with painful osteoarthritis (OA) of the carpometacarpal (CMC) joint and to examine rCBF variability across sessions. We used pulsed continuous arterial spin labeling (pCASL), a perfusion magnetic resonance imaging (MRI) technique. METHODS: The study included 16 patients with CMC OA and 17 matched controls. Two pCASL scans and numerical rating scale (NRS) estimates of ongoing pain were acquired in each of two identical sessions. Voxelwise general linear model analyses were performed to determine rCBF differences between OA and control groups, rCBF differences between sessions within each group, and whether sessionwise rCBF differences were related to variability in perceived ongoing pain. RESULTS: In the OA group, rCBF increases representing ongoing pain were identified in the primary and secondary somatosensory, insula, and cingulate cortices; thalamus; amygdala; hippocampus; and dorsal midbrain/pontine tegmentum, including the periaqueductal gray/nucleus cuneiformis. Sessionwise rCBF differences in the OA group in the postcentral, rostral/subgenual cingulate, mid/anterior insula, prefrontal, and premotor cortices were related to changes in perceived ongoing pain. No significant sessionwise rCBF differences were observed in controls. CONCLUSION: This is the first quantitative endogenous perfusion MRI study of the cerebral representation of ongoing, persistent pain due to OA. Observed rCBF changes potentially indicate dysregulated CNS appraisal and modulation of pain, most likely the maladaptive neuroplastic sequelae of living with painful OA. Understanding the neural basis of ongoing pain is likely to be important in developing novel treatment strategies.

Are Brazil nuts attractive?

We present event-driven simulation results for single and multiple intruders in a vertically vibrated granular bed. Under our vibratory conditions, the mean vertical position of a single intruder is governed primarily by a buoyancylike effect. Multiple intruders also exhibit buoyancy governed behavior; however, multiple neutrally buoyant intruders cluster spontaneously and undergo horizontal segregation. These effects can be understood by considering the dynamics of two neutrally buoyant intruders. We have measured an attractive force between such intruders which has a range of five intruder diameters, and we provide a mechanistic explanation for the origins of this force.