Mechanisms and Preventative Strategies for Persistent Pain following Knee and Hip Joint Replacement Surgery: A Narrative Review.

Chronic postsurgical pain (CPSP) following total knee arthroplasty (TKA) and total hip arthroplasty (THA) is a prevalent complication of joint replacement surgery which has the potential to decrease patient satisfaction, increase financial burden, and lead to long-term disability. The identification of risk factors for CPSP following TKA and THA is challenging but essential for targeted preventative therapy. Recent meta-analyses and individual studies highlight associations between elevated state anxiety, depression scores, preoperative pain, diabetes, sleep disturbances, and various other factors with an increased risk of CPSP, with differences observed in prevalence between TKA and THA. While the etiology of CPSP is not fully understood, several factors such as chronic inflammation and preoperative central sensitization have been identified. Other potential mechanisms include genetic factors (e.g., catechol-O-methyltransferase (COMT) and potassium inwardly rectifying channel subfamily J member 6 (KCNJ6) genes), lipid markers, and psychological risk factors (anxiety and depression). With regards to therapeutics and prevention, multimodal pharmacological analgesia, emphasizing nonopioid analgesics like acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs), has gained prominence over epidural analgesia. Nerve blocks and local infiltrative anesthesia have shown mixed results in preventing CPSP. Ketamine, an N-methyl-D-aspartate (NMDA)-receptor antagonist, exhibits antihyperalgesic properties, but its efficacy in reducing CPSP is inconclusive. Lidocaine, an amide-type local anesthetic, shows tentative positive effects on CPSP. Selective serotonin reuptake inhibitors (SSRIs) and serotonin norepinephrine reuptake inhibitors (SNRIs) have mixed results, while gabapentinoids, like gabapentin and pregabalin, present hopeful data but require further research, especially in the context of TKA and THA, to justify their use for CPSP prevention.

Pain: The Silent Public Health Epidemic.

More than 50 million Americans suffer from chronic pain, costing our society an estimated 565 to 635 billion dollars annually. Its complexity and training deficits in healthcare providers result in many patients receiving ineffective care. Large health inequities also exist in access to effective pain care for vulnerable populations. The traumatic history of indigenous people and people of color in regards to the experience of pain care perpetuates a lack of trust in the healthcare system, causing many to hesitate to seek medical treatment for painful events and conditions. Other vulnerable populations include those with sickle cell disease or fibromyalgia, whose experience of pain has not been well-understood. There are both barriers to care and stigma for patients with pain, including those taking prescribed doses of long-term opioids, those with known substance use disorder, and those with mental health diagnoses. The suffering of patients with pain can be "invisible" to the clinician, and to one's community at large. Pain can affect all people; but those most vulnerable to not getting effective care may continue to suffer in silence because their voices are not heard. Since 1973, pain societies around the globe have worked tirelessly to bring clinicians together to advance pain and opioid education, research, and patient care. These improvements consist of pain education, integrative treatment, and the understanding that a therapeutic alliance is critical to effective pain management. Pain education for both pre and post-licensure health professionals has increased substantially over the last decade. In addition, integrative and interdisciplinary approaches for clinical pain management are now considered best practices in pain care for patients with moderate to severe pain in addition to the development of a strong therapeutic alliance.

Pain control and functional recovery as therapeutic goals in patients with chronic musculoskeletal pain: two experiences with tapentadol hydrochloride.

OBJECTIVE: This study aimed to evaluate pain control, functioning, and quality of life (QoL) recovery in patients with chronic low back pain (cLBP) or post-traumatic osteoarthritis (OA) pain in the ankle/foot area, treated with tapentadol prolonged release and unresponsive to other treatments. PATIENTS AND METHODS: Two observational retrospective studies were conducted using clinical practice datasets of patients with chronic pain in cLBP and OA foot/ankle at different time points (total follow-up=60-90 days). The studies assessed pain intensity by the Numerical Rating Scale (NRS) pain scale (patients were classified as responder in case of ≥30% pain reduction), QoL by the 5-level EQ-5D (EQ-5D-5L) questionnaire, patient satisfaction by the 7-point Patients' Global Impression of Change (PGIC) scale; cLBP health status by the Roland Morris Disability Questionnaire (RMDQ); foot and ankle functional status by European Foot and Ankle Society (EFAS) score; and treatment-related AEs. RESULTS: For the cLBP setting, 37 patients were enrolled, of which 86.50% were classified as responders (n=32; CI: 75.5% ÷ 97.5%). For the foot/ankle OA pain setting, 21 patients were enrolled. Pain assessment at final follow-up was available only for 11 patients, of which 72.73% (n=8; CI: 39.0% ÷ 94.0%) were classified as responders. Statistically significant improvements were seen in the RMDQ, EQ-5D-5L, and PGIC scores in cLBP. Improvements in the EFAS, EQ-5D-5L, and PGIC scores were seen in OA as well. The incidence of treatment-related adverse reactions was low in both studies. CONCLUSIONS: In the study population, tapentadol prolonged release was effective and well tolerated in treating cLBP and post-traumatic foot/ankle OA chronic pain when used in a multimodal manner. The reduction in pain was accompanied by clinically relevant improvements in patients' functionality and QoL.

Cannabis medicine for chronic pain.

In the last decade, patients with chronic pain have expressed increasing interest in cannabis-derived products for adjuvant therapy when treatment is deemed refractory to conventional analgesics. At present, clinical evidence to support this treatment approach appears to be sparse. Not because clinical studies as such are lacking, but rather as a result of methodological bias in relation to study design, patient populations, and treatment protocols. In this review, research in cannabis medicine for relief of chronic pain is reviewed, mainly with reference to published meta-analytic studies.

Claims data analysis of provider-to-provider tele-mentoring program impact on opioid prescribing in Missouri.

OBJECTIVE: The objective of this study was to assess opioid prescribing patterns of primary care providers (PCPs) participating in a virtual tele-mentoring program for patients with chronic pain as compared to nonparticipants. DESIGN: We utilized Missouri Medicaid claims from 2013 to 2021 to compare opioid prescription dosages and daily supply of opioids prescribed by PCPs. Participants and nonparticipants were matched using propensity score matching. SETTING: Missouri Medicaid data were received through partnership with the Center for Health Policy's MO HealthNet Data Project, the state's leading provider of Medicaid data. PARTICIPANTS: Missouri-based prescribers. INTERVENTION: Show-Me Project Extension for Community Healthcare Outcomes (ECHO), an evidence-based provider-to-provider telehealth intervention that connects PCPs with a team of specialists. MAIN OUTCOME MEASURES: We compared the rate of prescription opioid >50 morphine milligram equivalents (MMEs), mean MMEs/day, and mean number of daily supply to understand the impact of the ECHO model on providers' opioid prescribing. RESULTS: Patients treated by ECHO providers have 33 percent lower odds of being prescribed opioid dose >50 MME/day (p < 0.001) compared to non-ECHO providers. There is also a 14 percent reduction in the average opioid dose prescribed to patients of ECHO providers (p < 0.001). We observed a 3 percent (p < 0.001) reduction in average daily supply of opioids among patients of ECHO providers compared to the comparison group. CONCLUSIONS: Pain Management ECHO supports PCPs with needed education and skills to provide specialty care in the management of pain conditions and safe prescribing of opioid medications.

The Impact of the COVID-19 Pandemic on Patient Disparities in Long-Term Opioid Therapy.

BACKGROUND: The COVID-19 pandemic disrupted how primary care patients with chronic pain received care. Our study sought to understand how long-term opioid therapy (LtOT) for chronic pain changed over the course of the pandemic overall and for different demographic subgroups. METHODS: We used data from electronic health records of 64 primary care clinics across Washington state and Idaho to identify patients who had a chronic pain diagnosis and were receiving long-term opioid therapy. We defined 10-month periods in 2019 to 2021 as prepandemic, early pandemic and late pandemic and used generalized estimating equations analysis to compare across these time periods and demographic characteristics. RESULTS: We found a proportional decrease in LtOT for chronic pain in the early months of the pandemic (OR = 0.94, P = .007) followed by an increase late pandemic (OR = 1.08, P = .002). Comparing late pandemic to prepandemic, identifying as Asian or Black, having fewer comorbidities, or living in an urban area were associated with higher likelihood of being prescribed LtOT. DISCUSSION: The use of LtOT for chronic pain in primary care has increased from before to after the COVID-19 pandemic with racial/ethnic and geographic disparities. Future research is needed to understand these disparities in LtOT and their effect on patient outcomes.

Trauma exposure across the lifespan among individuals engaged in treatment with medication for opioid use disorder: differences by gender, PTSD status, and chronic pain.

BACKGROUND: There is little study of lifetime trauma exposure among individuals engaged in medication treatment for opioid use disorder (MOUD). A multisite study provided the opportunity to examine the prevalence of lifetime trauma and differences by gender, PTSD status, and chronic pain. METHODS: A cross-sectional study examined baseline data from participants (N = 303) enrolled in a randomized controlled trial of a mind-body intervention as an adjunct to MOUD. All participants were stabilized on MOUD. Measures included the Trauma Life Events Questionnaire (TLEQ), the Brief Pain Inventory (BPI), and the Posttraumatic Stress Disorder Checklist (PCL-5). Analyses involved descriptive statistics, independent sample t-tests, and linear and logistic regression. RESULTS: Participants were self-identified as women (n = 157), men (n = 144), and non-binary (n = 2). Fifty-seven percent (n = 172) self-reported chronic pain, and 41% (n = 124) scored above the screening cut-off for PTSD. Women reported significantly more intimate partner violence (85%) vs 73%) and adult sexual assault (57% vs 13%), while men reported more physical assault (81% vs 61%) and witnessing trauma (66% vs 48%). Men and women experienced substantial childhood physical abuse, witnessed intimate partner violence as children, and reported an equivalent exposure to accidents as adults. The number of traumatic events predicted PTSD symptom severity and PTSD diagnostic status. Participants with chronic pain, compared to those without chronic pain, had significantly more traumatic events in childhood (85% vs 75%). CONCLUSION: The study found a high prevalence of lifetime trauma among people in MOUD. Results highlight the need for comprehensive assessment and mental health services to address trauma among those in MOUD treatment. TRIAL REGISTRATION: NCT04082637.

Emerging Molecular and Synaptic Targets for the Management of Chronic Pain Caused by Systemic Lupus Erythematosus.

Patients with systemic lupus erythematosus (SLE) frequently experience chronic pain due to the limited effectiveness and safety profiles of current analgesics. Understanding the molecular and synaptic mechanisms underlying abnormal neuronal activation along the pain signaling pathway is essential for developing new analgesics to address SLE-induced chronic pain. Recent studies, including those conducted by our team and others using the SLE animal model (MRL/lpr lupus-prone mice), have unveiled heightened excitability in nociceptive primary sensory neurons within the dorsal root ganglia and increased glutamatergic synaptic activity in spinal dorsal horn neurons, contributing to the development of chronic pain in mice with SLE. Nociceptive primary sensory neurons in lupus animals exhibit elevated resting membrane potentials, and reduced thresholds and rheobases of action potentials. These changes coincide with the elevated production of TNFα and IL-1ß, as well as increased ERK activity in the dorsal root ganglion, coupled with decreased AMPK activity in the same region. Dysregulated AMPK activity is linked to heightened excitability in nociceptive sensory neurons in lupus animals. Additionally, the increased glutamatergic synaptic activity in the spinal dorsal horn in lupus mice with chronic pain is characterized by enhanced presynaptic glutamate release and postsynaptic AMPA receptor activation, alongside the reduced activity of glial glutamate transporters. These alterations are caused by the elevated activities of IL-1ß, IL-18, CSF-1, and thrombin, and reduced AMPK activities in the dorsal horn. Furthermore, the pharmacological activation of spinal GPR109A receptors in microglia in lupus mice suppresses chronic pain by inhibiting p38 MAPK activity and the production of both IL-1ß and IL-18, as well as reducing glutamatergic synaptic activity in the spinal dorsal horn. These findings collectively unveil crucial signaling molecular and synaptic targets for modulating abnormal neuronal activation in both the periphery and spinal dorsal horn, offering insights into the development of analgesics for managing SLE-induced chronic pain.

Predictors of success of pharmacological management in patients with chronic lower back pain: systematic review.

BACKGROUND: Conservative management is recommended as the first therapeutic step in chronic low back pain (LBP), but there is no available evidence regarding the possible effect of patients' baseline characteristics on the therapeutic outcomes. A systematic review of the literature was performed to investigate this point. METHODS: In February 2024, all the level I studies investigating the role of pharmacological management for chronic LBP were accessed. Data concerning the patient demographic at baseline were collected: number of patients and related mean BMI and age, duration of the symptoms, duration of the follow-up, percentage of females, Numeric Rating Scale (NRS), the Roland Morris Disability Questionnaire (RMQ), Oswestry Disability Index (ODI). The outcomes at the last follow-up were evaluated through NRS, RMQ, and ODI. A multiple linear model regression diagnostic through the Pearson Product-Moment Correlation Coefficient (r) was used. RESULTS: Data from 47 articles (9007 patients) were obtained. The analysis yielded the following significant associations: age at baseline and NRS at follow-up (r = - 0.22; P = 0.04), NRS at baseline with NRS (r = 0.26; P = 0.03) and RMQ (r = - 0.58; P = 0.02) at follow-up, RMQ at baseline and the same at follow-up (r = 0.69; P = 0.0001). CONCLUSION: Older age, higher BMI, presence of comorbidities, higher ODI and a long history of symptoms or surgical treatments do not reduce the efficacy of pharmacological management of chronic LBP. However, pharmacological therapy is not an effective option for patients with high baseline RMQ. LEVEL OF EVIDENCE: I systematic review of RCTs.

Oral Delta-9-Tetrahydrocannabinol (THC) Increases Parasympathetic Activity and Supraspinal Conditioned Pain Modulation in Chronic Neuropathic Pain Male Patients: A Crossover, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: Disordered autonomic nervous system regulation and supraspinal pain inhibition have been repeatedly described in chronic pain. We aimed to explore the effects of δ-9-tetrahydrocannabinol (THC), an emerging treatment option, on autonomic nervous system and central pain modulation measures in patients with chronic pain. METHODS: Twelve male patients with chronic radicular neuropathic pain participated in a randomized, double-blind, crossover, placebo-controlled, single-administration trial. Low/high frequency (LF/HF) heart rate variability (HRV) ratio and conditioned pain modulation (CPM) response were measured and resting-state functional magnetic resonance imaging (MRI) was performed at baseline and after sublingual administration of either 0.2 mg/kg oral THC or placebo. RESULTS: THC significantly reduced the LF/HF ratio compared with placebo (interaction effect F(1,11) = 20.5; p < 0.005) and significantly improved CPM responses (interaction effect F(1,9) = 5.2; p = 0.048). The THC-induced reduction in LF/HF ratio correlated with increased functional connectivity between the rostral ventrolateral medulla and the dorsolateral prefrontal cortex [T(10) = 6.4, cluster p-FDR < 0.005]. CONCLUSIONS: THC shifts the autonomic balance towards increased parasympathetic tone and improves inhibitory pain mechanisms in chronic pain. The increase in vagal tone correlates with connectivity changes in higher-order regulatory brain regions, suggesting THC exerts top-down effects. These changes may reflect a normalizing effect of THC on multiple domains of supraspinal pain dysregulation. CLINICAL TRIAL REGISTRY NUMBER: NCT02560545.

Unveiling the link between chronic pain and misuse of opioids and cannabis.

Over 50 million Americans endure chronic pain where many do not receive adequate treatment and self-medicate to manage their pain by taking substances like opioids and cannabis. Research has shown high comorbidity between chronic pain and substance use disorders (SUD) and these disorders share many common neurobiological underpinnings, including hypodopaminergic transmission. Drugs commonly used for self-medication such as opioids and cannabis relieve emotional, bothersome components of pain as well as negative emotional affect that perpetuates misuse and increases the risk of progressing towards drug abuse. However, the causal effect between chronic pain and the development of SUDs has not been clearly established. In this review, we discuss evidence that affirms the proposition that chronic pain is a risk factor for the development of opioid and cannabis use disorders by outlining the clinical evidence and detailing neurobiological mechanisms that link pain and drug misuse. Central to the link between chronic pain and opioid and cannabis misuse is hypodopaminergic transmission and the modulation of dopamine signaling in the mesolimbic pathway by opioids and cannabis. Moreover, we discuss the role of kappa opioid receptor activation and neuroinflammation in the context of dopamine transmission, their contribution to opioid and cannabis withdrawal, along with potential new treatments.

Compounded Pain Formulations: What is the Evidence?

Pain syndromes are among the most widespread, costly, and debilitating of all neurological disorders. The number of patients living with chronic pain is expected to increase with the aging population and with the rise in obesity and diabetes across the nation. This type of pain is often insensitive to the traditional pain pharmacopeia or surgical intervention. Over the last 10 years the number of prescriptions that have been compounded by pharmacists has increased dramatically. There are a number of drugs in the area of pain management that have been formulated and compounded by pharmacists to treat conditions such as diabetic neuropathy, fibromyalgia, postherpetic neuralgia, joint pain, arthritis, and a variety of other conditions. A significant portion of these compounded analgesic preparations is made up of topical/transdermal dosage forms such as gels and creams. While the efficacy and doses of these drugs in systemic dosage forms have been widely established, little is known about the permeation and efficacy of these compounds from topical/transdermal gels. This review will provide an overview of chronic pain as a disease, the mechanisms of chronic pain, current treatment approaches to chronic pain, and a discussion of the drugs that are typically compounded into these topical formulations and studied in clinical trials.

Trends in U.S. Medical Cannabis Registrations, Authorizing Clinicians, and Reasons for Use From 2020 to 2022.

BACKGROUND: As medical cannabis availability increases, up-to-date trends in medical cannabis licensure can inform clinical policy and care. OBJECTIVE: To describe current trends in medical cannabis licensure in the United States. DESIGN: Ecological study with repeated measures. SETTING: Publicly available state registry data from 2020 to 2022. PARTICIPANTS: People with medical cannabis licenses and clinicians authorizing cannabis licenses in the United States. MEASUREMENTS: Total patient volume and prevalence per 10 000 persons in the total population, symptoms or conditions qualifying patients for licensure (that is, patient-reported qualifying conditions), and number of authorizing clinicians. RESULTS: In 2022, of 39 jurisdictions allowing medical cannabis use, 34 reported patient numbers, 19 reported patient-reported qualifying conditions, and 29 reported authorizing clinician numbers. Enrolled patients increased 33.3% from 2020 (3 099 096) to 2022 (4 132 098), with a corresponding 23.0% increase in the population prevalence of patients (175.0 per 10 000 in 2020 to 215.2 per 10 000 in 2022). However, 13 of 15 jurisdictions with nonmedical adult-use laws had decreased enrollment from 2020 to 2022. The proportion of patient-reported qualifying conditions with substantial or conclusive evidence of therapeutic value decreased from 70.4% (2020) to 53.8% (2022). Chronic pain was the most common patient-reported qualifying condition in 2022 (48.4%), followed by anxiety (14.2%) and posttraumatic stress disorder (13.0%). In 2022, the United States had 29 500 authorizing clinicians (7.7 per 1000 patients), 53.5% of whom were physicians. The most common specialties reported were internal or family medicine (63.4%), physical medicine and rehabilitation (9.1%), and anesthesia or pain (7.9%). LIMITATION: Missing data (for example, from California), descriptive analysis, lack of information on individual use patterns, and changing evidence base. CONCLUSION: Enrollment in medical cannabis programs increased overall but generally decreased in jurisdictions with nonmedical adult-use laws. Use for conditions or symptoms without a strong evidence basis continues to increase. Given these trends, more research is needed to better understand the risks and benefits of medical cannabis. PRIMARY FUNDING SOURCE: National Institute on Drug Abuse of the National Institutes of Health.

Effects of scapular treatment on chronic neck pain: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Chronic neck pain (CNP) is a common public health problem that affects daily living activities and quality of life. There is biomechanical interdependence between the neck and scapula. Studies have shown that shoulder blade function might be related to chronic neck pain. We therefore evaluated the effects of scapular targeted therapy on neck pain and function in patients with CNP. METHODS: Databases, including MEDLINE (via PubMed), EMBASE (via Ovid), Ovid, Web of Science, and Scopus, were systematically searched for randomized controlled trials published in English investigating treatment of the scapula for CNP before July 16, 2023. RESULTS: A total of 313 participants were included from 8 RCTs. Compared with those in the control group, the intervention in the scapular treatment group exhibited greater improvement in pain intensity (standardized mean difference (SMD) = 2.55; 95% CI = 0.97 to 4.13; P = 0.002), with moderate evidence. Subgroup analysis for pain intensity revealed a significant difference between the sexes, with only the female population (SMD = 6.23, 95% CI = 4.80 to 7.65) showing better outcomes than those with both sexes (SMD = 1.07, 95% CI = 0.57 to 1.56) (p < 0.00001). However, moderate evidence demonstrated no improvement in neck disability after scapular treatment (SMD of 0.24[-0.14, 0.62] of Neck Disability Index or Northwick Park Neck Pain Questionnaire). No effect of scapular treatment was shown on the pressure pain threshold (PPT). The cervical range of motion (CROM) and electromyographic activity of neck muscles could not be conclusively evaluated due to limited support in the articles, and further study was needed. However, the patient's head forward posture appeared to be corrected after scapular treatment. CONCLUSION: Scapular therapy was beneficial for relieving pain intensity in patients with CNP, especially in women. Head forward posture might also be corrected with scapular therapy. However, scapular therapy may have no effect on the PPT or neck disability. However, whether scapular therapy could improve CROM and cervical muscle activation in patients with CNPs had not been determined and needed further study.

CGRP neuropeptide levels in patients with endometriosis-related pain treated with dienogest: a comparative study.

BACKGROUND AND OBJECTIVE: Endometriosis (EM) involves the peripheral nervous system and causes chronic pain. Sensory nerves innervating endometriotic lesions contribute to chronic pain and influence the growth phenotype by releasing neurotrophic factors and interacting with nearby immune cells. Calcitonin gene-related peptide (CGRP), a pain-signaling neurotransmitter, has a significant role. This study examines the effect of Dienogest (DNG), a hormone therapy used for managing EM -related pain, on serum CGRP levels in EM patients. MATERIALS AND METHODS: The Visual Analog Scale (VAS) assessed pain in diagnosed EM. INDIVIDUALS: Serum samples were obtained to measure CGRP concentration. Participants received a 2 mg/day oral dose of DNG for six months as prescribed treatment. Additional serum samples were collected after this period to measure CGRP levels. RESULTS: In the EM group, 6.7%, 33.3%, and 20% had ovarian EM, ovarian plus uterosacral, and ovarian plus bladder, respectively. The EM group showed higher CGRP serum levels than the control group (80.53 ± 16.13 vs. 58.55 ± 6.93, P < 0.0001). Still, after drug administration, CGRP serum levels significantly decreased compared to pre-treatment levels (69.66 ± 11.53 vs. 80.53 ± 16.13, P < 0.05). The EM group showed higher pain compared to the control group (7.93 ± 1.58 vs. 0.13 ± 0.35, P < 0.0001), but after drug administration, pain significantly decreased compared to pre-treatment levels (1.00 ± 2.00 vs. 7.93 ± 1.58, P < 0.05). CONCLUSION: DNG administration reduces pain and serum CGRP levels in EM patients, offering the potential for innovative treatments and tailored options. Understanding neurotransmitter roles and drug effects can aid in discovering more effective modulators for these pathways.

A mouse model of chronic primary pain that integrates clinically relevant genetic vulnerability, stress, and minor injury.

Chronic primary pain conditions (CPPCs) affect over 100 million Americans, predominantly women. They remain ineffectively treated, in large part because of a lack of valid animal models with translational relevance. Here, we characterized a CPPC mouse model that integrated clinically relevant genetic (catechol-O-methyltransferase; COMT knockdown) and environmental (stress and injury) factors. Compared with wild-type mice, Comt+/- mice undergoing repeated swim stress and molar extraction surgery intervention exhibited pronounced multisite body pain and depressive-like behavior lasting >3 months. Comt+/- mice undergoing the intervention also exhibited enhanced activity of primary afferent nociceptors innervating hindpaw and low back sites and increased plasma concentrations of norepinephrine and pro-inflammatory cytokines interleukin-6 (IL-6) and IL-17A. The pain and depressive-like behavior were of greater magnitude and longer duration (≥12 months) in females versus males. Furthermore, increases in anxiety-like behavior and IL-6 were female-specific. The effect of COMT genotype × stress interactions on pain, IL-6, and IL-17A was validated in a cohort of 549 patients with CPPCs, demonstrating clinical relevance. Last, we assessed the predictive validity of the model for analgesic screening and found that it successfully predicted the lack of efficacy of minocycline and the CB2 agonist GW842166X, which were effective in spared nerve injury and complete Freund's adjuvant models, respectively, but failed in clinical trials. Yet, pain in the CPPC model was alleviated by the beta-3 adrenergic antagonist SR59230A. Thus, the CPPC mouse model reliably recapitulates clinically and biologically relevant features of CPPCs and may be implemented to test underlying mechanisms and find new therapeutics.

Chronic Low Back Pain in Adults: Evaluation and Management.

Chronic low back pain, defined as lumbar pain persisting for 12 weeks or more, occurs in about 13% of U.S. adults. Patients with chronic low back pain should have a history and physical examination to identify red flags that may indicate serious conditions that warrant immediate intervention or yellow flags (i.e., psychological, environmental, and social factors) that indicate risk of disability. The examination should include an evaluation for radicular symptoms. Routine imaging is not recommended but is indicated when red flags are present, there is a neuromuscular deficit, or if pain does not resolve with conservative therapy. Patients should avoid bed rest. Nonpharmacologic treatment is first-line management and may include therapies with varying evidence of support, such as counseling, exercise therapy, spinal manipulation, massage, heat, dry needling, acupuncture, transcutaneous electrical nerve stimulation, and physical therapy. Pharmacologic interventions are second-line treatment. Nonsteroidal anti-inflammatory drugs are the initial medication of choice; duloxetine may also be beneficial. Evidence is inconclusive to recommend the use of benzodiazepines, muscle relaxants, antidepressants, corticosteroids, insomnia agents, anticonvulsants, cannabis, acetaminophen, or long-term opioids. Epidural corticosteroid injections are not recommended except for short-term symptom relief in patients with radicular pain. Most patients with chronic low back pain will not require surgery; evaluation for surgery may be considered in those with persistent functional disabilities and pain from progressive spinal stenosis, worsening spondylolisthesis, or herniated disk. Physicians should consider prevention of chronic low back pain when patients present with acute back pain. Screening tools are available to predict the progression from acute to chronic low back pain, and targeted treatment strategies are beneficial for preventing progression.

Case Report: An Unexpected Complication of Intrathecal Therapy.

Traditionally, intrathecal therapy has been used for pain amelioration in cancer patients, but now has indications for nonmalignant chronic pain conditions. Due to its expanding use, it is imperative to understand the risks and management of intrathecal pump implantation. This case illustrates a series of uncommon intrathecal pump complications in a 52-year-old woman with complex regional pain syndrome. Considering the complications outlined in this case, there is a need to conduct retrospective studies and establish guidelines to address when it is optimal to remove a chronically placed catheter as well as the proper technique for removal.

Ultramicronized N-palmitoylethanolamine associated with analgesics: Effects against persistent pain.

Current epidemiological data estimate that one in five people suffers from chronic pain with considerable impairment of health-related quality of life. The pharmacological treatment is based on first- and second-line analgesic drugs, including COX-2 selective and nonselective nonsteroidal anti-inflammatory drugs, paracetamol, antidepressants, anti-seizure drugs and opioids, that are characterized by important side effects. N-palmitoylethanolamine (PEA) is a body's own fatty-acid ethanolamide belonging to the family of autacoid local injury antagonist amides. The anti-inflammatory and pain-relieving properties of PEA have been recognized for decades and prompted to depict its role in the endogenous mechanisms of pain control. Together with its relative abundance in food sources, this opened the way to the use of PEA as a pain-relieving nutritional intervention. Naïve PEA is a large particle size lipid molecule with low solubility and bioavailability. Reducing particle size is a useful method to increase surface area, thereby improving dissolution rate and bioavailability accordingly. Micron-size formulations of PEA (e.g., ultramicronized and co-(ultra)micronized) have shown higher oral efficacy compared to naïve PEA. In particular, ultramicronized PEA has been shown to efficiently cross the intestinal wall and, more importantly, the blood-brain and blood-spinal cord barrier. Several preclinical and clinical studies have shown the efficacy, safety and tolerability of ultramicronized PEA. This narrative review summarizes the available pharmacokinetic/pharmacodynamic data on ultramicronized PEA and focuses to its contribution to pain control, in particular as 'add-on' nutritional intervention. Data showing the ability of ultramicronized PEA to limit opioid side effects, including the development of tolerance, have also been reviewed.

Definición de la fibromialgia / Definition of fibromyalgia

El artículo define brevemente la fibromialgia dentro de un contexto más amplio incluyendo las raíces históricas del concepto y su posible etiología, así como su interpretación dentro de los modelos biopsicosociales más actuales, con implicaciones terapéuticas de alto interés.(AU)