Pharmacological treatment of chronic pain - the need for CHANGE

Looking for a Beam of Light to Heal Chronic Pain

Chronic pain (CP) is a leading cause of disability and a potential factor that affects biological processes, family relationships, and self-esteem of patients. However, the need for treatment of CP is presently unmet. Current methods of pain management involve the use of drugs, but there are different degrees of concerning side effects. At present, the potential mechanisms underlying CP are not completely clear. As research progresses and novel therapeutic approaches are developed, the shortcomings of current pain treatment methods may be overcome. In this review, we discuss the retinal photoreceptors and brain regions associated with photoanalgesia, as well as the targets involved in photoanalgesia, shedding light on its potential underlying mechanisms. Our aim is to provide a foundation to understand the mechanisms underlying CP and develop light as a novel analgesic treatment has its biological regulation principle for CP. This approach may provide an opportunity to drive the field towards future translational, clinical studies and support pain drug development.

Mobile health intervention to address chronic pain among those who engage in hazardous drinking: A pilot study

BACKGROUND

Hazardous drinking has been associated with chronic pain in community and medical samples. The purpose of this study was to develop a novel, integrated mobile health intervention that improves pain management and reduces hazardous drinking that may be implemented in primary care settings.

METHODS

Forty-eight participants with moderate or greater chronic pain and hazardous drinking were recruited from primary care clinics and through social media sites. Following baseline assessment, participants were randomized to a counselor-supported smartphone app intervention (INTV) or a counselor delivered treatment-as-usual control condition (CTL).

RESULTS

Results supported the feasibility and acceptability of the smartphone app intervention. Participants found it easy to use, reported high levels of satisfaction, and showed high levels of engagement with the app. Between-group effect size estimates at follow-up showed small effects for the intervention on pain ratings. However, using clinically meaningful change thresholds of 30% and 50% improvement in pain scores, 38% and 25% respectively of those in the INTV condition showed reductions compared to 20% and 12.5% respectively in the CTL condition. Effect size estimates did not indicate intervention superiority on alcohol outcomes as participants in both conditions showed considerable reductions in drinking over the course of the study.

CONCLUSIONS

Results supported the view that a mobile health intervention delivered via smartphone with electronic coaching is a feasible and acceptable method of addressing chronic pain among those who engage in hazardous drinking. Future work should test the efficacy of this approach in a fully powered trial.

The effectiveness of cupping therapy on low back pain: A systematic review and meta-analysis of randomized control trials

OBJECTIVES

This study aims to investigate the effectiveness of cupping therapy on low back pain (LBP).

METHODS

Medline, Embase, Scopus and WANFANG databases were searched for relevant cupping RCTs on low back pain articles up to 2023. A complementary search was manually made on 27 September for update screening. Full-text English and Chinese articles on all ethnic adults with LBP of cupping management were included in this study. Studies looking at acute low back pain only were excluded. Two independent reviewers screened and extracted data, with any disagreement resolved through consensus by a third reviewer. The methodological quality of the included studies was evaluated independently by two reviewers using an adapted tool. Change-from-baseline outcomes were treated as continuous variables and calculated according to the Cochrane Handbook. Data were extracted and pooled into the meta-analysis by Review Manager software (version 5.4, Nordic Cochrane Centre).

RESULTS

Eleven trials involving 921 participants were included. Five studies were assessed as being at low risk of bias, and six studies were of acceptable quality. High-quality evidence demonstrated cupping significantly improves pain at 2-8 weeks endpoint intervention (d=1.09, 95% CI: [0.35-1.83], p = 0.004). There was no continuous pain improvement observed at one month (d=0.11, 95% CI: [-1.02-1.23], p = 0.85) and 3-6 months (d=0.39, 95% CI: [-0.09-0.87], p = 0.11). Dry cupping did not improve pain (d=1.06, 95% CI: [-0.34, 2.45], p = 0.14) compared with wet cupping (d=1.5, 95% CI: [0.39-2.6], p = 0.008) at the endpoint intervention. There was no evidence indicating the association between pain reduction and different types of cupping (p = 0.2). Moderate- to low-quality evidence showed that cupping did not reduce chronic low back pain (d=0.74, 95% CI: [-0.67-2.15], p = 0.30) and non-specific chronic low back pain (d=0.27, 95% CI: [-1.69-2.24], p = 0.78) at the endpoint intervention. Cupping on acupoints showed a significant improvement in pain (d=1.29, 95% CI: [0.63-1.94], p < 0.01) compared with the lower back area (d=0.35, 95% CI: [-0.29-0.99], p = 0.29). A potential association between pain reduction and different cupping locations (p = 0.05) was found. Meta-analysis showed a significant effect on pain improvement compared to medication therapy (n = 8; d=1.8 [95% CI: 1.22 - 2.39], p < 0.001) and usual care (n = 5; d=1.07 [95% CI: 0.21- 1.93], p = 0.01). Two studies demonstrated that cupping significantly mediated sensory and emotional pain immediately, after 24 h, and 2 weeks post-intervention (d= 5.49, 95% CI [4.13-6.84], p < 0.001). Moderate evidence suggested that cupping improved disability at the 1-6 months follow-up (d=0.67, 95% CI: [0.06-1.28], p = 0.03). There was no immediate effect observed at the 2-8 weeks endpoint (d=0.40, 95% CI: [-0.51-1.30], p = 0.39). A high degree of heterogeneity was noted in the subgroup analysis (I2 >50%).

CONCLUSION

High- to moderate-quality evidence indicates that cupping significantly improves pain and disability. The effectiveness of cupping for LBP varies based on treatment durations, cupping types, treatment locations, and LBP classifications. Cupping demonstrated a superior and sustained effect on pain reduction compared with medication and usual care. The notable heterogeneity among studies raises concerns about the certainty of these findings. Further research should be designed with a standardized cupping manipulation that specifies treatment sessions, frequency, cupping types, and treatment locations. The actual therapeutic effects of cupping could be confirmed by using objective pain assessments. Studies with at least six- to twelve-month follow-ups are needed to investigate the long-term efficacy of cupping in managing LBP.

TRIAL REGISTRATION

This systematic review was initially registered on PROSPERO with registration code: CRD42021271245 on 08 September 2021.

Potential Role of Focal Microvibration (Equistasi®) in the Management of Chronic Pain: A Pilot Study

INTRODUCTION

Chronic pain is one of the leading causes of medical consultation with a dramatic psychophysical and socioeconomic impact. Focal microvibration (Equistasi®) is a revolutionary technology that converts the thermal energy of the skin into vibration. Equistasi® was shown to be effective in the treatment of gait and balance dysfunction in many pathological conditions such as Parkinson's disease and multiple sclerosis. Our aim was to explore the efficacy of focal microvibration in the management of chronic pain.

METHODS

We randomized 60 patients with pain of different origin into two groups: an experimental group (group E) treated with Equistasi, and a control group (group C) treated with standard pharmacological therapy. Pain, disability, and working capacity were evaluated by Brief Pain Inventory (BPI), Oswestry Disability Index (ODI), and Work Ability Index (WAI) at the baseline and after 7 (T7), 15 (T15), 30 (T30), 60 (T60), and 90 (T90) days.

RESULTS

According to BPI, average and worst pain in the last 24 h significantly decreased in group E at T15 and this result persisted up to T90; pain interference on general activity, mood, waling ability, normal work, relations with other people, sleep, and enjoyment of life decreased in group E with a significant improvement from T15. Lifting activity and work ability in relation to demands also significantly improved in group E. No significant changes in BPI, ODI, and WAI scores were recorded in group C during the follow-up.

CONCLUSIONS

Focal microvibration can be an effective tool for managing chronic pain in combination with other therapies.

Curcuma latifolia Roscoe extract reverses inflammatory pain in mice and offers a favorable CNS safety profile

ETHNOPHARMACOLOGICAL RELEVANCE

Curcuma latifolia Roscoe, a plant in the Curcuma genus, has been used as a food additive and folk medicine in Thailand to treat pelvic pain and improve premenstrual syndrome. Although it has been used for centuries, no scientific studies have proved its potential effects on inflammatory pain and central nervous system (CNS) safety profiles.

AIM OF THE STUDY

This study aimed to evaluate the potential effects of the ethanolic extract of C. latifolia rhizome on inflammatory pain in mice, together with its CNS safety profiles.

MATERIALS AND METHODS

First, network pharmacology was employed to identify the role of bioactive constituents in C. latifolia on inflammatory pain. In addition, in vitro pharmacology was also evaluated to confirm the anti-inflammatory activity of C. latifolia extract at cellular levels in activated macrophages and microglia. Furthermore, the efficacy of the plant extract in attenuating formalin-induced pain-like behaviors in mice was evaluated. Mice were orally administered the extract (125, 250, 500 mg/kg) followed by the measurement of formalin-induced pain-like behaviors. The LABORAS automated behavioral analysis and rotarod test were used to assess potential CNS side effects of C. latifolia extract (500 mg/kg) in mice.

RESULTS

The results demonstrated that major bioactive constituents present in C. latifolia have the ability to regulate multiple targets, biological processes and pathways associated with inflammatory pain as assessed by network pharmacology. C. latifolia modulated peripheral and central immune cells via reducing proinflammatory mediators (NO, TNF-α, and IL-6). C. latifolia extract improved formalin-induced pain-like behaviors in a dose-dependent manner during phase II of the formalin test. The efficacy of the plant extract at doses of 250 and 500 mg/kg was comparable to that of the positive control (indomethacin 10 mg/kg). Furthermore, the highest therapeutic dose of the extract did not affect motor coordination, exploratory behaviors, general behaviors, and overall well-being of mice, indicating no development of potential CNS adverse effects after administration of the extract.

CONCLUSION

These findings provide novel perspectives on using C. latifolia extract for pain management, considering its therapeutic efficacy and CNS safety.

Allosteric modulation of G protein-coupled receptors as a novel therapeutic strategy in neuropathic pain

Neuropathic pain is a debilitating pathological condition that presents significant therapeutic challenges in clinical practice. Unfortunately, current pharmacological treatments for neuropathic pain lack clinical efficacy and often lead to harmful adverse reactions. As G protein-coupled receptors (GPCRs) are widely distributed throughout the body, including the pain transmission pathway and descending inhibition pathway, the development of novel neuropathic pain treatments based on GPCRs allosteric modulation theory is gaining momentum. Extensive research has shown that allosteric modulators targeting GPCRs on the pain pathway can effectively alleviate symptoms of neuropathic pain while reducing or eliminating adverse effects. This review aims to provide a comprehensive summary of the progress made in GPCRs allosteric modulators in the treatment of neuropathic pain, and discuss the potential benefits and adverse factors of this treatment. We will also concentrate on the development of biased agonists of GPCRs, and based on important examples of biased agonist development in recent years, we will describe universal strategies for designing structure-based biased agonists. It is foreseeable that, with the continuous improvement of GPCRs allosteric modulation and biased agonist theory, effective GPCRs allosteric drugs will eventually be available for the treatment of neuropathic pain with acceptable safety.

An observational post-authorization safety study (PASS) of naloxegol drug utilization in four European countries

PURPOSE

Naloxegol has been shown to be an efficient alternative to treat opioid-induced constipation (OIC). This study aimed at describing the characteristics of naloxegol users and assessing patterns of naloxegol use and associated factors.

METHODS

This drug utilization cohort study used observational registry data on patients newly prescribed naloxegol in four European countries. Patient characteristics and patterns of naloxegol use and associated factors were described.

RESULTS

A total of 17 254 naloxegol users were identified across the countries. Their median age was 56-71 years, and each country had a majority of women (ranging 57.5%-62.9%). Multiple comorbidities, including cancer, were common. Natural opium alkaloids and osmotically acting laxatives (excluding saline) were the most frequently used opioids and laxatives. Overall prior use of opioids ranged from 91.9% to 99.6% and overall prior use of laxatives ranged from 69.9% to 92.4%. Up to 77.7% had prior use of medications with interaction potential, and up to 44.5% used them concurrently with naloxegol. Naloxegol was discontinued by 55.1%-90.9% of users, typically during the first 30 days. Approximately 10%-30% switched to or augmented the treatment with another constipation medication or restarted naloxegol after discontinuation. Augmentation with another constipation medication was relatively common, suggesting that naloxegol was used for multifactorial constipation.

CONCLUSION

The present study reflects real-world clinical use of naloxegol, including in vulnerable patient groups. Some naloxegol users lacked laxative or regular opioid use within six months before index date or used naloxegol concomitantly with medications presenting an interaction potential.

Changes in pain, daily occupations, lifestyle, and health following an occupational therapy lifestyle intervention: a secondary analysis from a feasibility study in patients with chronic high-impact pain

OBJECTIVES

This study explored changes in pain-related parameters, occupational function, occupational balance, lifestyle factors, and self-perceived health status in adults with chronic high-impact pain participating in an occupational therapy lifestyle intervention.

METHODS

This one-group longitudinal feasibility study was performed in three continuous feasibility rounds. The occupational therapists-led intervention targeted meaningful occupations, regular physical activity, and a healthy diet. The intervention contained individual and group sessions and was added to the standard multidisciplinary chronic pain treatment. Outpatients (n=40, 85 % females, 46.6 ± 10.9 years old) participated in the study between April 2019 and December 2021. The analysis includes data for 31 participants. Analysis of pre-post changes assessed after each feasibility round were performed for the outcomes: pain intensity, pain sensitivity and pain modulation (pressure pain threshold and tolerance, temporal summation of pain and conditioned pain modulation), pain self-efficacy, pain catastrophizing, motor and process skills, occupational balance, daily wake-time movement, daily walking steps, body mass index, waist circumference, blood pressure, and self-perceived health status.

RESULTS

Improvements in motor skills (assessment of motor and process skills score=0.20 (1.37; 1.57), 95 % CI 0.01; 0.38) and temporal summation of pain (-1.19 (2.86; -1.67), 95 % CI -2.16; -0.22), but a decrease in pain tolerance (-7.110 (54.42; 47.32), 95 % CI -13.99; -0.22) were observed. Correlation analysis suggested moderate-to-very strong statistically significant relationships in several outcomes related to pain, health, pain coping, occupational balance, occupational functioning, body anthropometrics, and pain sensitivity.

CONCLUSIONS

This study suggested that the lifestyle intervention would benefit motor skills while effects on other outcomes were unclear in adults with chronic pain. To confirm the findings, a randomized trial evaluating effectiveness is needed. Ethical committee number: SJ-307 Reg. Clinicaltrials.gov: NCT03903900.

Dysregulated neuromodulation in the anterior cingulate cortex in chronic pain

Chronic pain is a significant global socioeconomic burden with limited long-term treatment options. The intractable nature of chronic pain stems from two primary factors: the multifaceted nature of pain itself and an insufficient understanding of the diverse physiological mechanisms that underlie its initiation and maintenance, in both the peripheral and central nervous systems. The development of novel non-opioidergic analgesic approaches is contingent on our ability to normalize the dysregulated nociceptive pathways involved in pathological pain processing. The anterior cingulate cortex (ACC) stands out due to its involvement in top-down modulation of pain perception, its abnormal activity in chronic pain conditions, and its contribution to cognitive functions frequently impaired in chronic pain states. Here, we review the roles of the monoamines dopamine (DA), norepinephrine (NE), serotonin (5-HT), and other neuromodulators in controlling the activity of the ACC and how chronic pain alters their signaling in ACC circuits to promote pathological hyperexcitability. Additionally, we discuss the potential of targeting these monoaminergic pathways as a therapeutic strategy for treating the cognitive and affective symptoms associated with chronic pain.

Looking Back, Moving Forward in Pain Medicine

Pain is an ancient medical complaint and a clinical riddle that has never been entirely solved. Looking back into history was the springboard to a look into the future of pain medicine. This article was based on a series of presentations given in a recent congress (May 2023) and represents the research, views, and opinions of the authors. Opium has been used for millennia to treat pain, but when it gained broad use in the United States in the 1980s and 1990s, it was so vastly overprescribed and mis-prescribed that it led to a public health crisis. This, in turn, led to the reaction where opioids at times were under-prescribed, leaving out many patients who may have benefited from opioids while leaving many legacy pain patients to manage withdrawal on their own and with few analgesic options. Cannabinoids (CB) were likewise widely used for various conditions, including pain, but were outlawed in the 20th century, only to be brought back as a potential analgesic agent. Interventional pain medicine is a developing discipline and has reinforced the concept of the interdisciplinary pain clinic. It plays an increasingly important part in modern medicine overall, especially with the support of ultrasound, for both diagnosis and therapy. Today, the views about pain have changed. Anyone has accepted that pain is not purely a physical phenomenon but a biopsychosocial phenomenon that occurs within a cultural context. Pain management remains a small but vitally important medical subspecialty that is critical from a functional enablement and population health perspective, which is helping to navigate new therapeutic targets, new drugs and routes of administration, greater understanding of pain psychology, and new technologies. Pain control today means early intervention, functional enablement through pain alleviation, educating patients about pain management, and minimizing the transition from acute to chronic pain.

Iatrogenic Side Effects of Pain Therapies

Pain regimens, particularly for chronic cancer and noncancer pain, must balance the important analgesic benefits against potential risks. Many effective and frequently used pain control regimens are associated with iatrogenic adverse events. Interventional procedures can be associated with nerve injuries, vascular injuries, trauma to the spinal cord, and epidural abscesses. Although rare, these adverse events are potentially catastrophic. Pharmacologic remedies for pain must also consider potential side effects that can occur even at therapeutic doses of over-the-counter remedies such as paracetamol (acetaminophen) or nonsteroidal anti-inflammatory drugs. Opioids are effective pain relievers but are associated with many side effects, some of which can be treatment limiting. A prevalent and distressing side effect of opioid therapy is constipation. Opioid-induced constipation is caused by binding to opioid receptors in the gastrointestinal system, making conventional laxatives ineffective. Peripherally acting mu-opioid receptor antagonists are a new drug class that offers the benefits of preserving opioid analgesia without side effects in the gastrointestinal system. An important safety concern, particularly among geriatric patients is the increasingly prevalent condition of polypharmacy. Many senior patients take five or more medications, including some that may be contraindicated in geriatric patients, duplicative of other drugs, have potential pharmacokinetic drug-drug interactions, or may not be the optimal choice for the patient's age and condition. Careful assessment of medications in the elderly, including possibly deprescribing with tapering of certain drugs, may be warranted but should be done systematically and under clinical supervision.

Use of analgesics in Denmark: A national survey

People suffering from pain constitute a sizeable and heterogeneous patient group. Conventional oral analgesics are considered a cheap and safe first-line treatment. These drugs are used on both a regular and 'as needed' basis and are often obtained over-the-counter (OTC). We explored patient-reported patterns of use and adverse effects of analgesics in a community pharmacy questionnaire. Eight pharmacies invited persons aged ≥18 years requesting analgesics via prescription or OTC to complete an electronic questionnaire. A total of 2410 participants completed the questionnaire (68% female; 50% ≥ 60 years). Most participants filled a prescription for paracetamol (61%; n = 842) and non-steroidal analgesics (n = 363; 26%). Among OTC users, most obtained paracetamol (61%). Among prescription users, 73% (n = 1114) had their analgesic prescribed for daily use; however, of these only 61% (n = 630) reported using it daily, while 35% (n = 363) reported 'as needed' use. Of all prescriptions, 80% (n = 898) were labelled with the standardized indication 'against pain'. Self-reported indications showed that back pain and muscle/joint pain were the most common indications. Among non-new users of OTC analgesics (n = 841), 17% (n = 141) used their medication daily. Finally, 90% (n = 1658) of all participants reported not experiencing adverse effects. Our findings suggest a need for continuous assessment of analgesic patterns of use after treatment initiation to inform counselling in community pharmacies and elsewhere.

Electromyography-biofeedback for chronic low back pain: A qualitative cohort study

BACKGROUND AND AIMS

Surface electromyography-biofeedback (sEMG-BF) may reduce the burden of CLBP by improving physical functioning, sleep, pain catastrophizing, anxiety, and depression. This qualitative study investigated the impact of weekly EMG-BF sessions on adults with CLBP.

METHODS

Twenty-six individuals with CLBP participated in telephone interviews after completing an 8-week virtual sEMG-BF intervention. Trained interviewers conducted the 10-to-15-minute semi-structured interviews to understand participants' experience with the intervention. Common themes and subthemes were identified and analyzed using MAXQDA 2022 software.

RESULTS

Participants were predominantly middle-aged females (M = 45, range of 19 - 66) who have had exposure to utilizing conventional therapies such as physical therapy, chiropractor, and massage for the treatment of CLBP. This study focused on participants who reported their experience of the main outcome study which included perceived reductions in CLBP symptoms, including pain and stress, and positive effects on self-awareness and sleep. Three overarching themes emerged and were further divided into subthemes: participants' involvement (virtual experience, accessibility of device, and future recommendations) perceived benefits (participants gained awareness, recommendations for future treatment, met expectations, and implementation), and desire for flexibility (obstacles and COVID-19 Impact). No adverse effects were reported by any of the participants within the study.

CONCLUSIONS

Both physical and psychological improvements were reported by participants following an sEMG-BF intervention. Specific implementation procedures and critical barriers were identified. In particular, the ability to receive care for CLBP during the COVID-19 pandemic was important to participants.

Assessment and management of pain/nociception in patients with disorders of consciousness or locked-in syndrome: A narrative review

The assessment and management of pain and nociception is very challenging in patients unable to communicate functionally such as patients with disorders of consciousness (DoC) or in locked-in syndrome (LIS). In a clinical setting, the detection of signs of pain and nociception by the medical staff is therefore essential for the wellbeing and management of these patients. However, there is still a lot unknown and a lack of clear guidelines regarding the assessment, management and treatment of pain and nociception in these populations. The purpose of this narrative review is to examine the current knowledge regarding this issue by covering different topics such as: the neurophysiology of pain and nociception (in healthy subjects and patients), the source and impact of nociception and pain in DoC and LIS and, finally, the assessment and treatment of pain and nociception in these populations. In this review we will also give possible research directions that could help to improve the management of this specific population of severely brain damaged patients.

Mesenchymal stem cell spheroids alleviate neuropathic pain by modulating chronic inflammatory response genes

Chronic neuropathic pain is caused by dysfunction of the peripheral nerves associated with the somatosensory system. Mesenchymal stem cells (MSCs) have attracted attention as promising cell therapeutics for chronic pain; however, their clinical application has been hampered by the poor in vivo survival and low therapeutic efficacy of transplanted cells. Increasing evidence suggests enhanced therapeutic efficacy of spheroids formed by three-dimensional culture of MSCs. In the present study, we established a neuropathic pain murine model by inducing a chronic constriction injury through ligation of the right sciatic nerve and measured the therapeutic effects and survival efficacy of spheroids. Monolayer-cultured and spheroids were transplanted into the gastrocnemius muscle close to the damaged sciatic nerve. Transplantation of spheroids alleviated chronic pain more potently and exhibited prolonged in vivo survival compared to monolayer-cultured cells. Moreover, spheroids significantly reduced macrophage infiltration into the injured tissues. Interestingly, the expression of mouse-origin genes associated with inflammatory responses, Ccl11/Eotaxin, interleukin 1A, tumor necrosis factor B, and tumor necrosis factor, was significantly attenuated by the administration of spheroids compared to that of monolayer. These results suggest that MSC spheroids exhibit enhanced in vivo survival after cell transplantation and reduced the host inflammatory response through the regulation of main chronic inflammatory response-related genes.

Curcumin Diethyl γ-Aminobutyrate, a Prodrug of Curcumin, for Enhanced Treatment of Inflammatory Pain

Curcumin is a naturally occurring polyphenol compound with potential analgesic effects. It has been shown to improve pain-like behaviors in numerous models of pain. Despite its potential, curcumin exhibits poor physicochemical and pharmacokinetic properties, which hinder its oral therapeutic efficacy. Curcumin diethyl γ-aminobutyrate (CUR-2GE), a carbamate prodrug of curcumin, was designed to overcome these limitations and demonstrated greater anti-neuroinflammatory effects compared to curcumin in vitro. Thus, this study evaluated the effect of CUR-2GE and its parent compound on pain-like behaviors in carrageenan- and LPS-induced mouse models. The possible side effects of CUR-2GE were also assessed by exploring its effects on motor coordination and spontaneous locomotor activity after acute and chronic treatments. The results showed that CUR-2GE improved mechanical and thermal hyperalgesia and locomotor activity to a greater extent than curcumin in carrageenan-induced mice. These results are in line with the ability of CUR-2GE to suppress peripheral inflammation in the paw tissue of carrageenan-induced mice, indicated by a significant decrease in TNF-α and IL-6 expression levels. Similarly, in LPS-induced mice, CUR-2GE improved sickness and pain-like behaviors (exploratory behaviors and long-term locomotor activity) to a greater extent than curcumin. Furthermore, CUR-2GE significantly reduced the level of proinflammatory cytokines in both the plasma and spinal cord tissue of LPS-induced mice, exhibiting significantly higher inhibition than curcumin. Moreover, the motor coordination, and locomotive behaviors of mice were not affected by both acute and chronic administration of CUR-2GE, indicating no potential CNS side effects. Thus, CUR-2GE demonstrated enhanced therapeutic efficacy in mouse models of inflammatory pain without any possible CNS side effects, suggesting its potential to be developed as an analgesic agent against inflammatory pain.

Neurophysiology of hypnosis in chronic pain: A review of recent literature

Chronic pain is a complex phenomenon which includes biological, psychological, and socio-professional factors that undermine patients' everyday life. Currently, only few patients significantly benefit from pharmacological treatments and many have to stop them because of negative side effects. Moreover, no medication or treatment addresses all aspects of chronic pain at once (i.e., sensations, emotions, behaviors, and cognitions), positioning chronic pain as an important public health issue and thus contributing to high health-care costs. Consequently, patients and health-care providers are increasingly turning to complementary non-pharmacological techniques such as hypnosis. Clinical research has demonstrated a decrease of pain perception, pain interference, depression and anxiety, and an increase in global quality of life when patients with chronic pain have benefited from hypnosis learning. Neuroimaging studies offer a possible explanation of these results by focusing on neural processes of pain modulation in chronic pain patients' brain. Studies conducted with chronic pain patients showed a modulation of pain matrix activity during hypnosis with a specific involvement of the anterior cingulate cortex (related to emotional and cognitive processing of pain). Therefore, hypnosis seems to act upon regions underlying emotion and cognition, with an influence on pain perception and emotional regulation. In this review, we propose to carry out a review of the recent literature on hypnosis in chronic pain management. A better understanding of the beneficial effects of hypnosis on chronic pain and its neurophysiology should enable more systematic use of this technique in the management of this complex health problem.

Associations of health-related quality of life with sociodemographic characteristics, health, pain, and lifestyle factors, and motivation for changing lifestyle in adults living with chronic pain: a cross-sectional exploratory study

OBJECTIVES

We investigated the associations between health-related quality of life (HRQoL) and health, pain and lifestyle factors, as well as motivation for lifestyle changes, in adults living with chronic pain referred to a Danish pain centre.

METHODS

A total of 144 outpatients completed a questionnaire on HRQoL (EQ-5D-5L), health, pain, lifestyle factors (Body Mass Index [BMI], physical activity, smoking, alcohol, physical fitness, eating, sleep and stress) and motivation for lifestyle changes. We used multiple linear regression analyses to assess associations between HRQoL and the independent variables.

RESULTS

The participants (age mean 50 years, 81% females) had ≥2 body pain sites (93%), BMI≥25 (64%), sedentary lifestyle (43%) and multiple (n≥2) elevated metabolic risk factors (58%). Most considered lifestyle important for HRQoL (72%) and expressed moderate to very high motivation for changing lifestyle (92%). Poorer HRQoL in the study population was significantly associated with higher pain intensity in the most painful body site (β=-0.316, p=0.001) and very poor sleep quality (β=-0.410, p=0.024). Serious-to-extreme problems in usual activities were associated with significantly poorer health (β=-0.328, p=0.030).

CONCLUSIONS

Adults living with chronic pain participating in this survey had significantly lower self-evaluated HRQoL than the general population. Lower HRQoL was significantly associated with greater pain intensity and poor sleep quality. Serious-to-extreme problems in usual activities, such as work, study, housework, family and leisure, were associated with poorer self-evaluated health. We observed high frequencies of overweight, obesity, sedentary lifestyle, pain in multiple body sites and multiple lifestyle-related risk factors in the study population. Most participants felt motivated for changing lifestyle. Further interventions addressing pain alleviation, sleep quality, prevention of problems in usual activities and promotion of healthy lifestyle, e.g. physical activity and healthy eating, are needed to estimate the effect of a lifestyle-oriented approach on health and quality of life in people living with chronic pain. The results of this study will inform the research project reg. SJ-703, the Danish the Research Ethics Committee for Region Zealand, Denmark.

Beating Pain with Psychedelics: Matter over Mind?

Basic pain research has shed light on key cellular and molecular mechanisms underlying nociceptive and phenomenological aspects of pain. Despite these advances, [[we still yearn for] the discovery of novel therapeutic strategies to address the unmet needs of about 70% of chronic neuropathic pain patients whose pain fails to respond to opioids as well as to other conventional analgesic agents. Importantly, a substantial body of clinical observations over the past decade cumulatively suggests that the psychedelic class of drugs may possess heuristic value for understanding and treating chronic pain conditions. The present review presents a theoretical framework for hitherto insufficiently understood neuroscience-based mechanisms of psychedelics' potential analgesic effects. To that end, searches of PubMed-indexed journals were performed using the following Medical Subject Headings' terms: pain, analgesia, inflammatory, brain connectivity, ketamine, psilocybin, functional imaging, and dendrites. Recursive sets of scientific and clinical evidence extracted from this literature review were summarized within the following key areas: (1) studies employing psychedelics for alleviation of physical and emotional pain; (2) potential neuro-restorative effects of psychedelics to remediate the impaired connectivity underlying the dissociation between pain-related conscious states/cognitions and the subcortical activity/function leading to the eventual chronicity through immediate and long-term effects on dentritic plasticity; (3) anti-neuroinflammatory and pro-immunomodulatory actions of psychedelics as the may pertain to the role of these factors in the pathogenesis of neuropathic pain; (4) safety, legal, and ethical consideration inherent in psychedelics' pharmacotherapy. In addition to direct beneficial effects in terms of reduction of pain and suffering, psychedelics' inclusion in the analgesic armamentarium will contribute to deeper and more sophisticated insights not only into pain syndromes but also into frequently comorbid psychiatric condition associated with emotional pain, e.g., depressive and anxiety disorders. Further inquiry is clearly warranted into the above areas that have potential to evolve into further elucidate the mechanisms of chronic pain and affective disorders, and lead to the development of innovative, safe, and more efficacious neurobiologically-based therapeutic approaches.

Brain mechanisms of chronic pain: critical role of translational approach

Chronic pain is a leading cause of disability worldwide and its prevalence is likely to increase over the next decades. Treatment for chronic pain remains insufficient and therapeutical advances have not made comparable progress with that for many chronic disorders, thus amplifying the concern on the future burden of the disease. At the same time, and even after decades of intense research, the underlying pathophysiology of chronic pain remains minimally understood. We believe advancing our current understanding of chronic pain requires mechanistically explicit, hypothesis-driven, and clinically focused models. In this review we highlight some of the main findings over the last decades that have contributed to the present knowledge of brain mechanisms of chronic pain, and how such advances were possible due to a reverse translational research approach. We argue that this approach is essential in the chronic pain field, in order to generate new scientific hypotheses, probe physiological mechanisms, develop therapeutic strategies and translate findings back into promising human clinical trials.

The analgesic effect of electroencephalographic neurofeedback for people with chronic pain: A systematic review and meta-analysis

BACKGROUND

Electroencephalographic (EEG) neurofeedback has been utilized to regulate abnormal brain activity associated with chronic pain.

METHODS

In this systematic review, we synthesized the evidence from randomized controlled trials (RCTs) to evaluate the effect of EEG neurofeedback on chronic pain using random effects meta-analyses. Additionally, we performed a narrative review to explore the results of non-randomized studies. The quality of included studies was assessed using Cochrane risk of bias tools, and the GRADE system was used to rate the certainty of evidence.

RESULTS

Ten RCTs and 13 non-randomized studies were included. The primary meta-analysis on nine eligible RCTs indicated that although there is low confidence, EEG neurofeedback may have a clinically meaningful effect on pain intensity in short-term. Removing the studies with high risk of bias from the primary meta-analysis resulted in moderate confidence that there remained a clinically meaningful effect on pain intensity. We could not draw any conclusion from the findings of non-randomized studies, as they were mostly non-comparative trials or explorative case series. However, the extracted data indicated that the neurofeedback protocols in both RCTs and non-randomized studies mainly involved the conventional EEG neurofeedback approach, which targeted reinforcing either alpha or sensorimotor rhythms and suppressing theta and/or beta bands on one brain region at a time. A posthoc analysis of RCTs utilizing the conventional approach resulted in a clinically meaningful effect estimate for pain intensity.

CONCLUSION

Although there is promising evidence on the analgesic effect of EEG neurofeedback, further studies with larger sample sizes and higher quality of evidence are required.

Systematic Review of the Effectiveness of Machine Learning Algorithms for Classifying Pain Intensity, Phenotype or Treatment Outcomes Using Electroencephalogram Data

Recent attempts to utilize machine learning (ML) to predict pain-related outcomes from Electroencephalogram (EEG) data demonstrate promising results. The primary aim of this review was to evaluate the effectiveness of ML algorithms for predicting pain intensity, phenotypes or treatment response from EEG. Electronic databases MEDLINE, EMBASE, Web of Science, PsycINFO and The Cochrane Library were searched. A total of 44 eligible studies were identified, with 22 presenting attempts to predict pain intensity, 15 investigating the prediction of pain phenotypes and seven assessing the prediction of treatment response. A meta-analysis was not considered appropriate for this review due to heterogenos methods and reporting. Consequently, data were narratively synthesized. The results demonstrate that the best performing model of the individual studies allows for the prediction of pain intensity, phenotypes and treatment response with accuracies ranging between 62 to 100%, 57 to 99% and 65 to 95.24%, respectively. The results suggest that ML has the potential to effectively predict pain outcomes, which may eventually be used to assist clinical care. However, inadequate reporting and potential bias reduce confidence in the results. Future research should improve reporting standards and externally validate models to decrease bias, which would increase the feasibility of clinical translation. PERSPECTIVE: This systematic review explores the state-of-the-art machine learning methods for predicting pain intensity, phenotype or treatmentresponse from EEG data. Results suggest that machine learning may demonstrate clinical utility, pending further research and development. Areas for improvement, including standardized processing, reporting and the need for better methodological assessment tools, are discussed.

Mechanistic Insight into the Effects of Curcumin on Neuroinflammation-Driven Chronic Pain

Chronic pain is a persistent and unremitting condition that has immense effects on patients' quality of life. Studies have shown that neuroinflammation is associated with the induction and progression of chronic pain. The activation of microglia and astrocytes is the major hallmark of spinal neuroinflammation leading to neuronal excitability in the projection neurons. Excessive activation of microglia and astrocytes is one of the major contributing factors to the exacerbation of pain. However, the current chronic pain treatments, mainly by targeting the neuronal cells, remain ineffective and unable to meet the patients' needs. Curcumin, a natural plant product found in the Curcuma genus, improves chronic pain by diminishing the release of inflammatory mediators from the spinal glia. This review details the role of curcumin in microglia and astrocytes both in vitro and in vivo and how it improves pain. We also describe the mechanism of curcumin by highlighting the major glia-mediated cascades in pain. Moreover, the role of curcumin on inflammasome and epigenetic regulation is discussed. Furthermore, we discuss the strategies used to improve the efficacy of curcumin. This review illustrates that curcumin modulating microglia and astrocytes could assure the treatment of chronic pain by suppressing spinal neuroinflammation.

Complementary treatment comparison for chronic pain management: A randomized longitudinal study

Background

In chronic pain, it seems that the effect of cognitive-behavioral therapy (CBT) is boosted when it is combined with hypnosis. The aim of this study was to assess the efficacy of self-hypnosis combined with self-care (i.e., a type of CBT) compared to music/self-care, self-care and psychoeducation/CBT and to evaluate their long-term effects.

Methods

An open label randomized clinical trial enrolled patients with chronic pain and was carried out at the University Hospital of Liège (Belgium). Patients were randomized into four groups: self-hypnosis/self-care, music/self-care, self-care, psychoeducation/CBT (7 monthly sessions of 2 hours). Two follow-up sessions were delivered at 6- and 12-month. Levels of pain, fatigue intensity, anxiety, depression, insomnia severity, disability, health locus of control, mental and physical quality of life and attitudes (control, disability, harm, emotion, medical cure, medication, solicitude) towards pain were assessed before and after the treatments, and at follow-up.

Results

203 patients were randomized: 52 in self-hypnosis/self-care, 59 in music/self-care, 47 in self-care, and 45 in psychoeducation/CBT. No group effect was found. A significant time effect was showed. Directly after the treatment, all groups decreased in pain attitudes and physical quality of life. Perceived control increased. At 6-month, all patients kept their levels of physical quality of life and perceived control, and showed decrease in pain intensity, harm, emotion and medical cure. At 12-month, scores that had change previously remained ameliorated, a decrease in insomnia severity and an increase in internal locus of control were observed.

Conclusions

The present findings are encouraging as they display long-term beneficial effects of complementary biopsychosocial-based treatments in chronic pain. It seems that patients continued to apply the learnt strategies as improvements were observed one year after the treatments had ended.

Opioid Specific Effects on Central Processing of Sensation and Pain: A Randomized, Cross-Over, Placebo-Controlled Study

Moderate to severe pain is often treated with opioids, but central mechanisms underlying opioid analgesia are poorly understood. Findings thus far have been contradictory and none could infer opioid specific effects. This placebo-controlled, randomized, 2-way cross-over, double-blinded study aimed to explore opioid specific effects on central processing of external stimuli. Twenty healthy male volunteers were included and 3 sets of assessments were done at each of the 2 visits: 1) baseline, 2) during continuous morphine or placebo intravenous infusion and 3) during simultaneous morphine + naloxone or placebo infusion. Opioid antagonist naloxone was introduced in order to investigate opioid specific effects by observing which morphine effects are reversed by this intervention. Quantitative sensory testing, spinal nociceptive withdrawal reflexes (NWR), spinal electroencephalography (EEG), cortical EEG responses to external stimuli and resting EEG were measured and analyzed. Longer lasting pain (cold-pressor test - hand in 2° water for 2 minutes, tetanic electrical), deeper structure pain (bone pressure) and strong nociceptive (NWR) stimulations were the most sensitive quantitative sensory testing measures of opioid analgesia. In line with this, the principal opioid specific central changes were seen in NWRs, EEG responses to NWRs and cold-pressor EEG. The magnitude of NWRs together with amplitudes and insular source strengths of the corresponding EEG responses were attenuated. The decreases in EEG activity were correlated to subjective unpleasantness scores. Brain activity underlying slow cold-pressor EEG (1-4Hz) was decreased, whereas the brain activity underlying faster EEG (8-12Hz) was increased. These changes were strongly correlated to subjective pain relief. This study points to evidence of opioid specific effects on perception of external stimuli and the underlying central responses. The analgesic response to opioids is likely a synergy of opioids acting at both spinal and supra-spinal levels of the central nervous system. Due to the strong correlations with pain relief, the changes in EEG signals during cold-pressor test have the potential to serve as biomarkers of opioid analgesia. PERSPECTIVE: This exploratory study presents evidence of opioid specific effects on the pain system at peripheral and central levels. The findings give insights into which measures are the most sensitive for assessing opioid-specific effects.

From the pharmaceutical to the clinical: the case for effervescent paracetamol in pain management. A narrative review

OBJECTIVE

Paracetamol has an established place in the management of mild-to-moderate pain, but has certain limitations, including varying bioavailability, and potential hepatotoxicity if taken in overdose. Effervescent formulations may help to overcome these limitations.

METHODS

Pubmed searches, with no limits on date or language, were conducted in February 2020. Further references were identified from the reference lists of retrieved articles, and from the authors' knowledge of the field.

RESULTS

Effervescent formulations contain an organic acid (usually citric acid) and carbonate or bicarbonate salts (usually sodium bicarbonate). Upon contact with water, these react to form carbon dioxide, which facilitates the disintegration of the tablet and dissolution of the active drug. Moreover, sodium bicarbonate dose-dependently increases gastric emptying, which together with rapid dissolution facilitates drug absorption. In pharmacokinetic studies, effervescent formulations result in faster absorption of paracetamol than conventional oral formulations, and this translates into a faster onset of analgesia in clinical trials. Effervescent paracetamol has a favorable safety profile, with good tolerability. Importantly, the sodium content of some preparations does not appear to increase cardiovascular risk under real world conditions. Effervescent formulations may also offer advantages in terms of ease of administration and palatability.

CONCLUSIONS

Effervescent formulations of paracetamol result in faster drug absorption, and hence more rapid analgesia, than oral tablets, and offer a favorable tolerability and safety profile. The use of such formulations may therefore help to promote appropriate use of paracetamol.

The Efficacy of Acetominophen for Total Laparoscopic Hysterectomy

OBJECTIVE

Despite limited data, acetaminophen, along with other agents, is commonly included in enhanced recovery after surgery (ERAS) protocols following laparoscopic hysterectomy. We aimed to systematically review the efficacy of acetaminophen on the management of postoperative pain after laparoscopic hysterectomy.

METHODS

We searched PubMed, SCOPUS, Web of Science, and Cochrane Library databases for relevant clinical trials investigating the role of acetaminophen in the management of pain after laparoscopic hysterectomy. We performed the risk of bias according to Cochrane's risk of bias tool. We performed the analysis of homogeneous data under the fixed-effects model during the analysis of heterogeneous data under the random-effects model. The primary outcome was the assessment of pain score after 2, 6, 12, and 24 h.

RESULTS

A total of 495 patients in 13 trials were included in our meta-analysis. Acetaminophen was not superior at reducing postoperative pain scores. Further analysis at progressive temporal points revealed no further significance; effect size at after 2 h (SMD = -0.020, 95% CI (-0.216; 0.176)), 6 h (SMD = -0.115, 95% CI (-0.312; 0.083)), 12 h (SMD = -0.126, 95% CI (-0.277; 0.025)), or 24 h (SMD = 0.063, 95% CI (-0.065; 0.191)). Pooled analysis was heterogeneous (P < 0.1); therefore, we conducted a sensitivity analysis yielding homogeneous results. The drug did not reduce opioid need (MD = -0.16, 95% CI (-2.39, 2.06), P = 0.89).

CONCLUSION

We conclude that acetaminophen is not beneficial for reducing pain after laparoscopic hysterectomy. Other alternatives have better results. Caution should be given to the inclusion of acetaminophen in ERAS protocols designed for laparoscopic hysterectomy, especially as a single agent or to reduce opioid consumption.

Ending the Chase: Experiences of Rural Individuals with Opioid Use Disorder

The US remains in the midst of an opioid overdose epidemic. Given that rural populations have higher rates of opioid-related morbidity and mortality, it is important to understand the factors that perpetuate opioid use and facilitate recovery in rural communities. Purpose: To explore experiences of individuals living with opioid use disorder (OUD) and to analyze these experiences within a broader sociocultural context. Methods: Using a descriptive, qualitative design, we interviewed twenty purposefully sampled participants. We used thematic content analysis to identify themes and patterns. Results: As participants became dependent, the chase for opioids was to avoid the pain of withdrawal. Waking up sick became an everyday experience, leading to a lifestyle of hustling. The pursuit of opioids resulted in physical, social, emotional, and legal consequences that fed a cycle of stigmatization. In recovery, participants learned to embrace a new way of thinking, allowing them to make new choices. The strong influence of family and community in their lives was a key factor in their resiliency and opioid use experiences. Conclusions: Individuals with OUD are impacted by intersecting social, physical, economic and policy factors that reinforce the expansion of the opioid epidemic rurally. This study provided a voice to rural individuals with opioid use disorder, a group often underrepresented in the literature, providing an understanding of their struggles and the unique sociocultural dynamics that exist in rural northern New Mexico. The complex sociocultural relationships to family and community represent important adaptive factors that could support individual healing and community transformation.

Telemonitoring in Chronic Pain Management Using Smartphone Apps: A Randomized Controlled Trial Comparing Usual Assessment against App-Based Monitoring with and without Clinical Alarms

BACKGROUND

The usefulness of mHealth in helping to target face-to-face interventions for chronic pain more effectively remains unclear. In the present study, we aim to test whether the Pain Monitor mobile phone application (app) is well accepted by clinicians, and can help improve existent medical treatments for patients with chronic musculoskeletal pain. Regarding this last goal, we compared three treatment conditions, namely usual treatment, usual treatment with an app without alarms and usual treatment with an app with alarms. All treatments lasted one month. The three treatments were compared for all outcomes, i.e., pain severity and interference, fatigue, depressed mood, anxiety and anger.

METHODS

In this randomized controlled trial, the usual monitoring method (i.e., onsite; n = 44) was compared with daily ecological momentary assessment using the Pain Monitor app-both with (n = 43) and without alarms (n = 45). Alarms were sent to the clinicians in the presence of pre-established undesired clinical events and could be used to make treatment adjustments throughout the one-month study.

RESULTS

With the exception of anger, clinically significant changes (CSC; 30% improvement) were greater in the app + alarm condition across outcomes (e.g., 43.6% of patients experienced a CSC in depressed mood in the app + alarm condition, which occurred in less than 29% of patients in the other groups). The clinicians were willing to use the app, especially the version with alarms.

CONCLUSIONS

The use of apps may have some benefits in individual health care, especially when using alarms to tailor treatments.

Kynurenine and Tetrahydrobiopterin Pathways Crosstalk in Pain Hypersensitivity

Despite the identification of molecular mechanisms associated with pain persistence, no significant therapeutic improvements have been made. Advances in the understanding of the molecular mechanisms that induce pain hypersensitivity will allow the development of novel, effective, and safe therapies for chronic pain. Various pro-inflammatory cytokines are known to be increased during chronic pain, leading to sustained inflammation in the peripheral and central nervous systems. The pro-inflammatory environment activates additional metabolic routes, including the kynurenine (KYN) and tetrahydrobiopterin (BH4) pathways, which generate bioactive soluble metabolites with the potential to modulate neuropathic and inflammatory pain sensitivity. Inflammation-induced upregulation of indoleamine 2,3-dioxygenase 1 (IDO1) and guanosine triphosphate cyclohydrolase I (GTPCH), both rate-limiting enzymes of KYN and BH4 biosynthesis, respectively, have been identified in experimental chronic pain models as well in biological samples from patients affected by chronic pain. Inflammatory inducible KYN and BH4 pathways upregulation is characterized by increase in pronociceptive compounds, such as quinolinic acid (QUIN) and BH4, in addition to inflammatory mediators such as interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α). As expected, the pharmacologic and genetic experimental manipulation of both pathways confers analgesia. Many metabolic intermediates of these two pathways such as BH4, are known to sustain pain, while others, like xanthurenic acid (XA; a KYN pathway metabolite) have been recently shown to be an inhibitor of BH4 synthesis, opening a new avenue to treat chronic pain. This review will focus on the KYN/BH4 crosstalk in chronic pain and the potential modulation of these metabolic pathways that could induce analgesia without dependence or abuse liability.

Pathophysiologic Approach to Pain Therapy for Complex Pain Entities: A Narrative Review

Pain management is challenging for both clinicians and patients. In fact, pain patients are frequently undertreated or even completely untreated. Optimal treatment is based on targeting the underlying mechanisms of pain and tailoring the management modality for each patient using a personalized approach. This narrative review deals with pain conditions that have a complex underlying mechanism and need an individualized and frequently multifactorial approach to pain management. The research is based on previously conducted studies, and does not contain any studies with human participants or animals performed by any of the authors. This is not an exhaustive review of the current evidence. However, it provides the clinician with a perspective on pain therapy targeting the underlying pain mechanism(s). When dealing with complex pain conditions, the prudent physician benefits from having a deep knowledge of various underlying pain mechanisms in order to provide a plan for optimal pharmacological pain relief to patients.

Personality and psychiatric disorders in chronic pain male affected by erectile dysfunction: prospective and observational study

The prevalence of personality disorders (PDs) and sexual dysfunction in chronic pain patients is higher than in general population. Our main objective was to analyse the influence of PD in patients with erectile dysfunction and chronic non-cancer pain and their response to andrological treatment. One-hundred one patients were included along 30 months. Pain intensity, quality of life, sexual life quality, anxiety and depression were analysed together with opioid dose. Erectile functioning was measured with the International Index of Erectile Function (IIEF) and PDs with Millon Clinical Multiaxial Inventory (MCMI-III). The mean age was 57 ± 12 years old, with moderate to severe pain, 70% were sexually active and presented moderate to severe ED. PDs were very frequent (31%, cut-off 85 and 84% cut-off 75 scores) mostly anxiety, compulsive, though disorder, somatoform and narcissistic. Self-defeating feature presence was significantly correlated (r = -0.4, 95% CI = -0.605 to -0.145, p = 0.002) with a more severe baseline ED and narcissistic, and a better response to andrological treatment (p = 0.010, d = 1.082). Patients with dysthymia features required significantly higher opioid doses vs. control (238 vs. 102 mg/day, respectively). These findings underline the importance of diagnosing PDs to rigorously treat patients with chronic pain and ED.

Pentameric Ligand-Gated Ion Channels as Pharmacological Targets Against Chronic Pain

Chronic pain is a common detrimental condition that affects around 20% of the world population. The current drugs to treat chronic pain states, especially neuropathic pain, have a limited clinical efficiency and present significant adverse effects that complicates their regular use. Recent studies have proposed new therapeutic strategies focused on the pharmacological modulation of G-protein-coupled receptors, transporters, enzymes, and ion channels expressed on the nociceptive pathways. The present work intends to summarize recent advances on the pharmacological modulation of pentameric ligand-gated ion channels, which plays a key role in pain processing. Experimental data have shown that novel allosteric modulators targeting the excitatory nicotinic acetylcholine receptor, as well as the inhibitory GABA_A and glycine receptors, reverse chronic pain-related behaviors in preclinical assays. Collectively, these evidences strongly suggest the pharmacological modulation of pentameric ligand-gated ion channels is a promising strategy towards the development of novel therapeutics to treat chronic pain states in humans.

Improving chronic pain management with eHealth and mHealth: study protocol for a randomised controlled trial

INTRODUCTION

Chronic pain has become a matter of public health concern due to its high prevalence and because public costs associated with treatment and disability increase each year. Research suggests that limitations in the traditional assessment of chronic pain patients limit the effectiveness of current medical treatments. The use of technology might serve change patient traditional monitoring into ecological momentary assessments, which might be visualised by physicians live. This study describes a randomised control trial designed to test the utility of a technology-based solution for pain telemonitoring consisting of a smartphone app for patients and a web application for physicians. The goal of this study will be to explore whether this combination of eHealth and mHealth improves the effectiveness of existing pain treatments.

METHODS AND ANALYSIS

Participants will be 250 patients randomly assigned to one of these two conditions: treatment-as-usual (TAU) and TAU +app+ web. All participants will receive the usual treatment for their pain. Only the TAU +app+ web group use Pain Monitor app, which generates alarms that are sent to the physicians in the face of previously established undesired events. Physicians will be able to monitor app reports using a web application, which might result in an adjustment of treatment. We anticipate that the use of Pain Monitor plus the therapist web will result in a reduction of pain intensity and side effects of the medication. Improvements on secondary outcomes, namely fatigue, mood, pain interference, rescue medication use and quality of life, are also expected. Mixed repeated-measure multivariate analyses of variances will be conducted to investigate whether there are differences between preassessment and postassessment scores as a function of the experimental condition.

ETHICS AND DISSEMINATION

Ethical approval from the Hospital General Universitari de Castellon was obtained. The findings will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03606265.

Electroacupuncture Alleviates Spared Nerve Injury-Induced Neuropathic Pain And Modulates HMGB1/NF-κB Signaling Pathway In The Spinal Cord

Background

Neuropathic pain with complications greatly affects patients worldwide. High mobility group box 1 (HMGB1) has been shown to contribute to the pathogenesis of neuropathic pain; thus, suppression of HMGB1 may provide a novel therapeutic option for neuropathic pain. Electroacupuncture (EA) has been indicated to be effective in attenuating neuropathic pain, but the underlying mechanism remains to be fully clarified. We aim to explore whether 2Hz EA stimulation regulates the spinal HMGB1/NF-κB signaling in neuropathic pain induced by spared nerve injury (SNI).

Materials and methods

Paw withdrawal threshold and CatWalk gait analysis were used to assess the effect of 2Hz EA on pain-related behaviors in SNI rats. Administration of 2Hz EA to SNI rats once every other day lasting for 21 days. Expression of spinal protein molecules were detected using Western blot and immunofluorescence staining.

Results

It was found that SNI significantly induced mechanical hypersensitivity and decrease of gait parameters, and subsequently increased the levels of HMGB1, TLR4, MyD88, and NF-κB p65 protein expression. 2Hz EA stimulation led to remarkable attenuation of mechanical hypersensitivity, upregulation of spinal HMGB1, TLR4, MyD88, and NF-κB p65 protein expressions induced by SNI, and significant improvement in gait parameters. Furthermore, immunofluorescence staining also confirmed that 2Hz EA obviously suppressed the co-expression of microglia activation marker CD11b and TLR4 or MyD88, as well as the activation of NF-κB p65 in SNI rats.

Conclusion

This study suggested that blockade of HMGB1/NF-κB signaling in the spinal cord may be a promising therapeutic approach for 2Hz EA management of SNI-induced neuropathic pain.

Validity, Reliability, Feasibility, and Usefulness of Pain Monitor: A Multidimensional Smartphone App for Daily Monitoring of Adults With Heterogenous Chronic Pain

OBJECTIVES

Ecological momentary assessment has been recommended in the management of chronic pain. Smartphone apps might be a useful tool for that purpose. This goal of this study was to develop and test a multidimensional smartphone app for adults with chronic pain. A multidisciplinary team developed the app content after a series of meetings, considering clinical guidelines for pain measurement. The content included pain intensity and interference, fatigue, mood, perceived health status, activity level, side effects of the medication, use of rescue medication, and pain-related sychological constructs (catastrophizing, acceptance, fear, and coping).

METHODS

Thirty-eight participants (21 to 59 y) used the app, called Pain Monitor, twice a day during 30 consecutive days. Patients completed a set of well-established measures at the beginning and end of the study via paper-and-pencil. Weekly phone assessments were also made for pain intensity, pain interference, fatigue, and mood.

RESULTS

Construct validity was revealed by moderate-to-strong correlations between app content and traditional measures. Feasibility was supported by high compliance (between 70% and 82%) and high acceptability and ease of use. Both side effects of the medication and use of rescue medication were found to be useful tools to guide treatment.

DISCUSSION

The new assessment protocol in the app allows for an easy and rapid multidimensional assessment of chronic pain patients.

Towards an Effective and Safe Treatment of Inflammatory Pain: A Delphi-Guided Expert Consensus

OBJECTIVE

The clinical management of inflammatory pain requires an optimal balance between effective analgesia and associated safety risks. To date, mechanisms associated with inflammatory pain are not completely understood because of their complex nature and the involvement of both peripheral and central mechanisms. This Expert Consensus document is intended to update clinicians about evolving areas of clinical practice and/or available treatment options for the management of patients with inflammatory pain.

METHOD

An international group of experts in pain management covering the pharmacology, neurology and rheumatology fields carried out an independent qualitative systematic literature search using MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials.

RESULTS

Existing guidelines for pain management provide recommendations that do not satisfactorily address the complex nature of pain. To achieve optimal outcomes, drug choices should be individualized to guarantee the best match between the characteristics of the patient and the properties of the medication. NSAIDs represent an important prescribing choice in the management of inflammatory pain, and the recent results on paracetamol question its appropriate use in clinical practice, raising the need for re-evaluation of the recommendations in the clinical practice guidelines.

CONCLUSIONS

Increasing clinicians' knowledge of the available pharmacologic options to treat different pain mechanisms offers the potential for safe, individualized treatment decisions. We hope that it will help implement the needed changes in the management of inflammatory pain by providing the best strategies and new insights to achieve the ultimate goal of managing the disease and obtaining optimal benefits for patients.

FUNDING

Dompé Farmaceutici SPA and Paolo Procacci Foundation.

A Novel Algorithm to Identify Predictors of Treatment Response: Tapentadol Monotherapy or Tapentadol/Pregabalin Combination Therapy in Chronic Low Back Pain?

Purpose: High dose monotherapies or drug combinations are used to achieve sufficient analgesia for the treatment of severe chronic low back pain, before invasive therapy options are considered. In order to demonstrate an alternative for an empirical treatment approach, the authors' primary aim was to present an algorithm for the objective identification of treatment predictors. Additionally, the study identified baseline-characteristics in chronic low back pain patients prior to tapentadol PR treatment, as well as scrutinized those patients, either benefitting from a medium/high dose tapentadol PR monotherapy or a combination therapy (medium dose tapentadol PR + pregabalin).

Patients and Methods: The statistical approach included data of a previously published randomized, double blind, phase 3b study which compared the effectiveness and safety of tapentadol PR vs. a combination of tapentadol PR and pregabalin. In total, 46 clinical parameters were included in the statistical prediction models which were applied separately either to 50 patients who already responded well during the titration period (i.e., medium dose tapentadol PR) or to 261 patients with in the comparative treatment period [i.e., monotherapy (high dose tapentadol PR) or combination therapy (medium dose tapentadol PR/pregabalin)].

Results: The first statistical model identified three co-variables (NRS-3, PDQ, SQ) with predictive effects on patients responding well (“optimal responders”) to a medium dose tapentadol PR titration. Those patients presented low baseline pain intensity scores, good sleep quality and high painDETECT scores. The second statistical model identified eight co-variables (PDQ, numbness, SF-12 MCS, SF-12 PCS, VAS, HADS-A, HADS-D, SQ) with predictive effects on patients responding to high dose tapentadol PR monotherapy vs. a combination therapy (tapentadol PR + pregabalin). The high dose tapentadol PR responders indicated high painDETECT scores, little numbness and a good mental health status. Whereas, the combination therapy (tapentadol PR + pregabalin) responders were characterized by severe sleep disturbances and little anxiety.

Conclusion: The statistical analysis characterized chronic low back pain patients and identified factors contributing to a treatment response. Thus, this retrospective statistical algorithm represents an elegant method, which may contribute to future strategies toward a more individualized and improved mechanism based pain therapy.

Genetic Contribution in Low Back Pain: A Prospective Genetic Association Study

OBJECTIVES

Chronic pain is one of the most common reasons individuals seek medical attention. It is a major issue because of the wide interindividual variability in the analgesic response. This might be partly explained by the presence of variants in genes encoding molecules involved in pharmacodynamics and pharmacokinetics. The aim was to analyze opioid effectiveness in chronic low back pain (CLBP) relief after opioid titration, unveiling the impact of pharmacogenetics.

METHODS

The study included 231 opioid-naïve patients from the Spine Unit; age 63 ± 14 years, 64% female, body mass index 29 ± 6 kg/m² , visual analog scale pain intensity score 73 ± 16 mm. Clinical data were collected at baseline, 3 months after opioid titration, and after 2 to 4 years of follow-up concerning pain (intensity and relief), quality of life, disability, comorbidities, and drug prescription (opioid dose, rotations, and adverse events). The genotype influence of OPRM1, COMT, UGT2B7, ABCB1, KCNJ6, and CYP3A5*3A in analgesic response was analyzed by reverse-transcription polymerase chain reaction genotyping.

RESULTS

Patients with the COMT G472A-AA genotype (rs4680) and KCNJ6 A1032G-A allele (rs2070995) CLBP responded differently to opioid titration, with higher pain intensity requiring higher dosing. Furthermore, GG- genotypes of A118G (OPRM1, rs1799971) and A854G (UGT2B7, rs776746) influenced the neuropathic component. After opioid titration, CLBP intensity, neuropathic component, low back pain disability, anxiety, and depression significantly decreased, while quality of life improved.

CONCLUSION

Single-nucleotide polymorphisms in genes involved in pain transmission and opioid metabolism might predispose to exaggerated sensitivity and differences in the opioid analgesic effect in patients with CLBP. We encourage clinical trials for their clinical application in chronic pain management.

Epidemiology of Chronic Pain in the Latium Region, Italy: A Cross-Sectional Study on the Clinical Characteristics of Patients Attending Pain Clinics

In Italy, chronic pain affects more than a quarter of the population, whereas the average European prevalence is 21%. This high prevalence might be due to the high percentage of Italian people who do not receive treatment, even after the passing of law 38/2010 (the right to access pain management in Italy), which created a regional network for the diagnosis and treatment of noncancer chronic pain. Italian epidemiologic studies on chronic pain are scanty, and this observational, multicenter, cross-sectional study is the first to investigate the clinical characteristics of patients who attended the pain management clinics in the Latium Region, Italy, for the management of their noncancer chronic pain. A total of 1,606 patients (mean age 56.8 years, standard deviation ± 11.4), 67% women, were analyzed. Severe pain was present in 54% of the sample. Women experienced pain and had it in two or more sites more often than men (57% vs. 50%, p = .02; and 55.2% vs. 45.9%, p < .001, respectively). Chronic pain was musculoskeletal (45%), mixed (34%), and neuropathic (21%). In more than 60% of the cases, chronic pain was continuous, and in 20% it had lasted for more than 48 months; long-lasting pain was often neuropathic. Low back (33.4%) and lower limbs (28.2%) were the main locations. Severe intensity of pain was statistically significantly associated with female gender (odds ratio [OR] 1.39; 95% confidence interval [CI] 1.06-1.84); with International Classification of Diseases, Ninth Revision, codes for chronic pain syndrome (OR 2.14; 95% CI 1.55-2.95); and with continuous pain (OR 2.02; 95% CI 1.54-2.66). Neuropathic pain and mixed pain were significantly associated with number of sites, and a trend seemed to be present (OR 2.11 and 3.02 for 2 and 3 + sites; 95% CI 1.59-2.79 and 2.00-4.55, respectively).

Pain prevalence and treatment in patients with metastatic bone disease

The accomplishment of successful pain treatment requires evaluation, characterization and quantification. The present study characterized pain and survival in a cohort of patients with cancer with bone metastasis who were treated with intravenous bisphosphonates. A total of 84 patients self-completed the Brief Pain Inventory (BPI) and 36-Item Short Form Survey (SF-36), between November 2010 and March 2011 with a 5-year survival follow-up as a surrogate marker of cancer burden. The median age was 62 years old (34–85), 64% of patients were female and 58% of these females had breast cancer. In the population, self-reported pain was 91.6%, with 29 patients (34.5%) reporting severe pain (score 7–10). Among these patients, only 13 (44.8%) presented a similar report to that of their clinical files and 5 were undergoing treatment with strong opioids (17.2%). A total of 45 patients (46%) had not been prescribed analgesic drugs, of these patients, 32 were treated with a weak opioid, and 13 with a strong opioid. An association was observed between pain records and the prescribed analgesic (P=0.031). BPI maximum pain and overall survival data were analyzed, and a significant association was identified between male patients presenting severe pain and decreased survival (P=0.004). Male survival was associated with severe pain, which is consistent with other data. The results revealed a skeletal-related events (SRE)-free survival (time elapsed from diagnosis of the first bone metastasis to the first SRE) of 9 months (4.39–13.73, 95% CI) with a statistically significant difference between subgroups of time since diagnosis of bone metastasis (P=0.005). The added value of the present study is the suggestion that complete and accurate pain narratives are mandatory and may contribute to the optimization of analgesia, and may help to increase survival rates. Optimal pain management for patients with cancer remains an urgent requirement.

Costs and consequences of chronic pain due to musculoskeletal disorders from a health system perspective in Chile

Background:

Chronic pain is a prevalent and distressing condition caused by an unceasing pain lasting more than 3 months or a pain that persists beyond the normal healing time. There is evidence of inadequate management partly explained by the unawareness regarding the magnitude of the problem.

Objectives:

To estimate the annual expected costs and consequences of chronic pain caused by musculoskeletal diseases from the health system perspective in Chile.

Methods:

A Markov cohort model was built to represent chronic pain and estimate expected costs and consequences over 1-year time horizon. Transition probabilities were obtained through expert elicitation. Consequences examined were: years lost to disability (YLD), depression, anxiety, and productivity losses. Direct health care costs were estimated using local sources. Probabilistic sensitivity analysis was performed to characterize second-order uncertainty.

Results:

The annual expected cost due to musculoskeletal chronic pain was estimated in USD $1387.2 million, equivalent to 0.417% of the national GDP. Lower back pain and osteoarthritis of the knee explained the larger proportion of the total cost, 31.8% and 27.1%, respectively. Depression attributed to chronic pain is another important consequence accounting for USD $94 million (Bayesian credibility interval 95% $49.1–$156.26). Productivity losses were also important cost, although early retirement and presenteeism were not measured. Chronic pain causes 137,037 YLDs.

Conclusion:

Chronic pain is not only an important cause of disability but also responsible for high social and financial burden in Chile. Public health programs focused on managing chronic pain may decrease burden of disease and possibly reduce costs.

Trends in analgesic consumption in France over the last 10 years and comparison of patterns across Europe

AIMS

The aims of the present study were to describe the consumption trends of three groups of analgesics (non-opioids, and mild and strong opioids) between 2006 and 2015 in France, and compare this pattern of use with six European countries in 2015.

METHODS

Annual drugs sales were extracted from the French national authority's consumption database, and from the IMS Multinational Integrated Data Analysis System and national databases for European countries.

RESULTS

The use of mild opioids in France was found to have decreased by 53% over the past 10 years, owing to the declining use of dextropropoxyphene combinations, along with an increase in the use of non-opioids and strong opioids (from 72 to 93, and 2 to 2.8 defined daily doses/1000 inhabitants/day, respectively). Paracetamol, the most consumed analgesic, increased over this period, particularly for the adult high dose (+140%). The use of tramadol and codeine combinations also increased, by 62% and 42%, respectively. Morphine remained the most used strong opioid, although there were also large increases in the consumption of oxycodone (+613%) and fentanyl (+263% and +72% for transmucosal and transdermal forms, respectively). A comparison of the patterns of use in Europe in 2015 showed a higher consumption of mild and strong opioids in the UK. France ranked first and third place, respectively, for paracetamol and mild opioid consumption, whereas its use of strong opioids was among the lowest.

CONCLUSIONS

Paracetamol consumption is clearly highest in France, whereas its use of strong opioids is among the lowest in Europe, although its consumption of oxycodone has increased significantly. Further studies are required specifically to monitor these drugs.

Magnetic Resonance Neurography in Chronic Lumbosacral and Pelvic Pain: Diagnostic and Management Impact-Institutional Audit

BACKGROUND/OBJECTIVE

Low back and pelvic pain are among the most prevalent conditions worldwide, with major social and economic costs. The aim of this study was to evaluate the role of magnetic resonance neurography (MRN) of lumbosacral plexus in the management and outcomes of these patients with chronic pain.

METHODS

Consecutive patients with chronic lumbosacral and pelvic pain referred for MRN over a year were included. Preimaging and postimaging clinical diagnosis and treatment, pain levels, and location were recorded. Pain-free survival was compared between treatments using a Cox proportional hazards model.

RESULTS

A total of 202 patients with mean age 53.7 ± 14.8 years and a male/female ratio of 1:1.53 were included. Of these patients, 115 presented with radiculopathy (57%), 56 with pelvic pain (28%), and 31 with groin pain (15%). Mean initial pain level was 6.9 ± 1.9. Mean symptom duration was 4.21 ± 5.86 years. Of these patients, 143 (71%) had a change in management because of MRN. After MRN, reduction in pain levels was observed in 21 of 32 patients receiving conservative treatment (66%), 42 of 67 receiving injections (63%), and 27 of 33 receiving surgery (82%). Follow-ups were available in 131 patients. Median pain-free survival was 12 months. Patients treated with surgery had significantly lower pain recurrence than patients receiving other treatments in the same time frame (hazard ratio, 3.6; 95% confidence interval, 1.4-9.2; P = 0.0061).

CONCLUSIONS

MRN use in chronic lumbosacral and pelvic pain led to a meaningful change in diagnosis and treatment. After MRN, conservative treatment and injections provided pain relief; however, patients benefited more from surgery than from any other treatment.

TLR4-mediated autophagic impairment contributes to neuropathic pain in chronic constriction injury mice

Neuropathic pain is a complex, chronic pain state characterized by hyperalgesia, allodynia, and spontaneous pain. Accumulating evidence has indicated that the microglial Toll-like receptor 4 (TLR4) and autophagy are implicated in neurodegenerative diseases, but their relationship and role in neuropathic pain remain unclear. In this study, we examined TLR4 and its association with autophagic activity using a chronic constriction injury (CCI)-induced neuropathic pain model in wild-type (WT) and TLR4-knockout (KO) mice. The mice were assigned into four groups: WT-Contralateral (Contra), WT-Ipsilateral (Ipsi), TLR4 KO-Contra, and TLR4 KO-Ipsi. Behavioral and mechanical allodynia tests and biochemical analysis of spinal cord tissue were conducted following CCI to the sciatic nerve. Compared with the Contra group, mechanical allodynia in both the WT- and TLR4 KO-Ipsi groups was significantly increased, and a marked decrease of allodynia was observed in the TLR4 KO-Ipsi group. Although glial cells were upregulated in the WT-Ipsi group, no significant change was observed in the TLR4 KO groups. Moreover, protein expression and immunoreactive cell regulation of autophagy (Beclin 1, p62) were significantly increased in the neurons, but not microglia, of WT-Ipsi group compared with the WT-Contra group. The level of PINK1, a marker for mitophagy was increased in the neurons of WT, but not in TLR4 KO mice. Together, these results show that TLR4-mediated p62 autophagic impairment plays an important role in the occurrence and development of neuropathic pain. And what is more, microglial TLR4-mediated microglial activation might be indirectly coupled to neuronal autophage.