Pregabalin produces analgesia in males but not females in an animal model of chronic widespread muscle pain.

Introduction: Pregabalin, which acts on the αδ-1 subunit of voltage-gated calcium channels, relieves ≥50% of pain in a third of individuals with fibromyalgia. Thus far, preclinical studies of pregabalin have predominantly used male animals.

Objectives: The purpose of our study was to investigate potential sex differences in the analgesic efficacy of pregabalin that may contribute to disparities in human outcomes.

Impact of electronic health record updates and changes on the delivery and monitoring of interventions in embedded pragmatic clinical trials.

The NIH Pragmatic Trials Collaboratory supports the design and conduct of 32 embedded pragmatic clinical trials, and many of these trials rely on data from the electronic health record (EHR) to monitor outcomes and/or use functionality provided by the EHR platform to deliver the intervention. Given the complexity and dynamic nature of EHR systems, study teams have encountered challenges in use of the EHR for these purposes, including challenges related to local implementation of trial interventions, rapid technology evolution, EHR updates, and transitions in EHR systems. In this article, we share case examples and lessons learned, and suggest that teams need to be aware of-and perhaps proactively investigate- possible changes to EHR systems and data that will affect the delivery of interventions and the integrity and safety of pragmatic clinical trials.

Female specific interactions of serotonin and testosterone in the rostral ventromedial medulla after activity-induced muscle pain.

Classical preclinical studies show that serotonin (5-HT) injected into the rostral ventromedial medulla (RVM) produces analgesia that is blocked by 5-HT2 receptor antagonists. One key modulator of 5-HT activity is the serotonin transporter (SERT) which reduces serotonergic signaling through reuptake into the presynaptic terminal. In the activity-induced muscle pain model, females show widespread pain and increased SERT expression in the RVM whereas males show localized pain and no changes in SERT expression.

Special Section on Patient-Reported Outcomes and Informatics: Collection of Patient-Reported Outcome Measures in Rural and Underserved Populations.

The NIH Pragmatic Trials Collaboratory supports the design and conduct of 31 embedded pragmatic clinical trials, and many of these trials use patient-reported outcome measures (PROMs) to provide valuable information about their patients' health and wellness. Often these trials enroll medically underserved patients, including people with incomes below the federal poverty threshold, racial or ethnically minoritized groups, or rural or frontier communities. In this series of trial case reports, we provide lessons learned about collecting PROMs in these populations.

Categories of the Patient-Specific Functional Scale Activities in Chronic Neck Pain and Their Relationship to the Neck Disability Index.

Common outcome measures for chronic neck pain are the Patient-Specific Functional Scale (PSFS) and the neck disability index (NDI). The primary aim was to categorize the top-rated, patient-selected functional activity limitations of the PSFS to determine if there were consistent limited functional activities for individuals with chronic neck pain and how these compared to the constructs of activities on the NDI. The secondary aim was to determine the relationship between scores for individuals who completed both the NDI and PSFS.

Local Synthesis of Estradiol in the Rostral Ventromedial Medulla Protects against Widespread Muscle Pain in Male Mice.

Animal studies consistently demonstrate that testosterone is protective against pain in multiple models, including an animal model of activity-induced muscle pain. In this model, females develop widespread muscle hyperalgesia, and reducing testosterone levels in males results in widespread muscle hyperalgesia. Widespread pain is believed to be mediated by changes in the central nervous system, including the rostral ventromedial medulla (RVM).

Brain-derived neurotrophic factor contributes to activity-induced muscle pain in male but not female mice.

Activity-induced muscle pain increases interleukin-1β (IL-1β) release from muscle macrophages and the development of hyperalgesia is prevented by blockade of IL-1β in muscle. Brain derived neurotrophic factor (BDNF) is released from sensory neurons in response to IL-1β and mediates both inflammatory and neuropathic pain. Thus, we hypothesize that in activity-induced pain, fatigue metabolites combined with IL-1β activate sensory neurons to increase BDNF release, peripherally in muscle and centrally in the spinal dorsal horn, to produce hyperalgesia.

The influence of sex on activity in voluntary wheel running, forced treadmill running, and open field testing.

Introduction: Physical activity is commonly used for both measuring and treating dysfunction. While preclinical work has been historically biased towards males, the use of both male and female animals is gaining popularity after multiple NIH initiatives. With increasing inclusion of both sexes, it has become imperative to determine sex differences in common behavioral assays.

Effects of transcutaneous electrical nerve stimulation on pain, function, and descending inhibition in people with non-specific chronic low-back pain: a study protocol for a randomized crossover trial.

Background: Low back pain (LBP) is a significant public health problem, is very prevalent, and is often characterized by the persistence of symptoms. Transcutaneous electrical nerve stimulation (TENS) may benefit people with chronic LBP because it can activate descending inhibitory pathways and inhibit central excitability. However, previous studies that have investigated the effects of TENS on pain in people with LBP have failed to use proper intensities of current, and the timing of the assessment of pain was not performed during the peak of the analgesic response or functional activities.

Minimal Clinically Important Change of Movement Pain in Musculoskeletal Pain Conditions.

Movement pain, which is distinct from resting pain, is frequently reported by individuals with musculoskeletal pain. There is growing interest in measuring movement pain as a primary outcome in clinical trials, but no minimally clinically important change (MCIC) has been established, limiting interpretations. We analyzed data from 315 participants who participated in previous clinical trials (65 with chronic Achilles tendinopathy; 250 with fibromyalgia) to establish an MCIC for movement pain.

Wireless Transcutaneous Electrical Nerve Stimulation (TENS) for Chronic Chemotherapy-Induced Peripheral Neuropathy (CIPN): A Proof-of-Concept Randomized Clinical Trial.

Chemotherapy-induced peripheral neuropathy (CIPN) affects approximately 30 to 60% of people who receive neurotoxic chemotherapy. CIPN is associated with impaired quality of life and function and has few effective treatments. This 6-site, subject and assessor-blinded randomized clinical trial (RCT) was designed to assess 1) preliminary efficacy (ie, alpha pre-specified at .

Brain-derived neurotrophic factor contributes to activity-induced muscle pain in male but not female mice.

Activity-induced muscle pain increases release of interleukin-1β (IL-1β) in muscle macrophages and the development of pain is prevented by blockade of IL-1β. Brain derived neurotrophic factor (BDNF) is released from sensory neurons in response to IL-1β and mediates both inflammatory and neuropathic pain. Thus, we hypothesized that metabolites released during fatiguing muscle contractions activate macrophages to release IL-1β, which subsequently activate sensory neurons to secrete BDNF.

Predicting chronic postsurgical pain: current evidence and a novel program to develop predictive biomarker signatures.

Chronic pain affects more than 50 million Americans. Treatments remain inadequate, in large part, because the pathophysiological mechanisms underlying the development of chronic pain remain poorly understood. Pain biomarkers could potentially identify and measure biological pathways and phenotypical expressions that are altered by pain, provide insight into biological treatment targets, and help identify at-risk patients who might benefit from early intervention.

Reliability and validity of two-dimensional motion capture to assess ankle dorsiflexion motion and heel raise work.

Objectives: To determine the inter-rater reliability and criterion validity of two-dimensional (2D) measures of ankle function in the sagittal plane for participants with Achilles tendinopathy (AT).

Design: Cohort study.

Setting: University Laboratory, Participants, Adults with AT (N = 18, Women: 72.

Influence of routine exercise on the peripheral immune system to prevent and alleviate pain.

Routine physical activity reduces the onset of pain and exercise is a first line treatment for individuals who develop chronic pain. In both preclinical and clinical research regular exercise (routine exercise sessions) produces pain relief through multiple mechanisms such as alterations in the central and peripheral nervous system. More recently, it has been appreciated that exercise can also alter the peripheral immune system to prevent or reduce pain.

Efficacy of Telehealth for Movement-Evoked Pain in People With Chronic Achilles Tendinopathy: A Noninferiority Analysis.

Objective: The purpose of this study was to compare the efficacy of physical therapy delivered via an all telehealth or hybrid format with an all in-person format on movement-evoked pain for individuals with chronic Achilles tendinopathy (AT).

Methods: Sixty-six individuals with chronic AT participated (age, 43.4 [SD = 15.

Preoperative Exercise Has a Modest Effect on Postoperative Pain, Function, Quality of Life, and Complications: A Systematic Review and Meta-Analysis.

Objective: Preoperative exercise (prehabilitation) is commonly used as a method to reduce pain and improve function postoperatively. The purpose of this systematic review was to determine therapeutic benefits of preoperative exercise on postoperative pain, function, quality of life (QOL), and risk of complications across various types of surgeries.

Methods: Three electronic databases were used to perform a literature search.

The impact of sex and physical activity on the local immune response to muscle pain.

Induction of muscle pain triggers a local immune response to produce pain and this mechanism may be sex and activity level dependent. The purpose of this study was to measure the immune system response in the muscle following induction of pain in sedentary and physically active mice. Muscle pain was produced via an activity-induced pain model using acidic saline combined with fatiguing muscle contractions.

P2X7-NLRP3-Caspase-1 signaling mediates activity-induced muscle pain in male but not female mice.

We developed an animal model of activity-induced muscle pain that is dependent on local macrophage activation and release of interleukin-1β (IL-1β). Activation of purinergic type 2X (P2X) 7 receptors recruits the NOD-like receptor protein (NLRP) 3 and activates Caspase-1 to release IL-1β. We hypothesized that pharmacological blockade of P2X7, NLRP3, and Caspase-1 would prevent development of activity-induced muscle pain in vivo and release of IL-1β from macrophages in vitro.

Standing on the shoulders of bias: lack of transparency and reporting of critical rigor characteristics in pain research.

Rigorous experimental design with transparent reporting in biomedical science reduces risk of bias and allows for scientists to judge the quality of the research. Basic factors of rigor such as blinding, randomization, power analysis, and inclusion of both sexes impact the reproducibility by reducing experimental bias. We designed a systematic study to analyze basic factors of rigor, inclusion of sex, and whether data were analyzed or disaggregated by sex over the past 10 years in the journal PAIN .

Intervention delivery for embedded pragmatic clinical trials: Development of a tool to measure complexity.

Background: Conducting an embedded pragmatic clinical trial in the workflow of a healthcare system is a complex endeavor. The complexity of the intervention delivery can have implications for study planning, ability to maintain fidelity to the intervention during the trial, and/or ability to detect meaningful differences in outcomes.

Methods: We conducted a literature review, developed a tool, and conducted two rounds of phone calls with NIH Pragmatic Trials Collaboratory Demonstration Project principal investigators to develop the Intervention Delivery Complexity Tool.

Selective androgen receptor modulator microparticle formulation reverses muscle hyperalgesia in a mouse model of widespread muscle pain.

Chronic pain is a significant health problem associated with disability and reduced quality of life. Current management of chronic pain is inadequate with only modest effects of pharmacological interventions. Thus, there is a need for the generation of analgesics for treating chronic pain.