Pain chronification: what should a non-pain medicine specialist know?

OBJECTIVE

Pain is one of the most common reasons for an individual to consult their primary care physician, with most chronic pain being treated in the primary care setting. However, many primary care physicians/non-pain medicine specialists lack enough awareness, education and skills to manage pain patients appropriately, and there is currently no clear, common consensus/formal definition of "pain chronification".

METHODS

This article, based on an international Change Pain Chronic Advisory Board meeting which was held in Wiesbaden, Germany, in October 2016, provides primary care physicians/non-pain medicine specialists with a narrative overview of pain chronification, including underlying physiological and psychosocial processes, predictive factors for pain chronification, a brief summary of preventive strategies, and the role of primary care physicians and non-pain medicine specialists in the holistic management of pain chronification.

RESULTS

Based on currently available evidence, we propose the following consensus-based definition of pain chronification which provides a common framework to raise awareness among non-pain medicine specialists: "Pain chronification describes the process of transient pain progressing into persistent pain; pain processing changes as a result of an imbalance between pain amplification and pain inhibition; genetic, environmental and biopsychosocial factors determine the risk, the degree, and time-course of chronification."

CONCLUSIONS

Early intervention plays an important role in preventing pain chronification and, as key influencers in the management of patients with acute pain, it is critical that primary care physicians are equipped with the necessary awareness, education and skills to manage pain patients appropriately.

Targeting pain at its source in sickle cell disease

Sickle cell disease (SCD) is a genetic disorder associated with hemolytic anemia, end-organ damage, reduced survival, and pain. One of the unique features of SCD is recurrent and unpredictable episodes of acute pain due to vasoocclusive crisis requiring hospitalization. Additionally, patients with SCD often develop chronic persistent pain. Currently, sickle cell pain is treated with opioids, an approach limited by adverse effects. Because pain can start at infancy and continue throughout life, preventing the genesis of pain may be relatively better than treating the pain once it has been evoked. Therefore, we provide insights into the cellular and molecular mechanisms of sickle cell pain that contribute to the activation of the somatosensory system in the peripheral and central nervous systems. These mechanisms include mast cell activation and neurogenic inflammation, peripheral nociceptor sensitization, maladaptation of spinal signals, central sensitization, and modulation of neural circuits in the brain. In this review, we describe potential preventive/therapeutic targets and their targeting with novel pharmacologic and/or integrative approaches to ameliorate sickle cell pain.

Local anaesthetics and regional anaesthesia versus conventional analgesia for preventing persistent postoperative pain in adults and children

BACKGROUND

Regional anaesthesia may reduce the rate of persistent postoperative pain (PPP), a frequent and debilitating condition. This review was originally published in 2012 and updated in 2017.

OBJECTIVES

To compare local anaesthetics and regional anaesthesia versus conventional analgesia for the prevention of PPP beyond three months in adults and children undergoing elective surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to December 2016 without any language restriction. We used a combination of free text search and controlled vocabulary search. We limited results to randomized controlled trials (RCTs). We updated this search in December 2017, but these results have not yet been incorporated in the review. We conducted a handsearch in reference lists of included studies, review articles and conference abstracts. We searched the PROSPERO systematic review registry for related systematic reviews.

SELECTION CRITERIA

We included RCTs comparing local or regional anaesthesia versus conventional analgesia with a pain outcome beyond three months after elective, non-orthopaedic surgery.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trial quality and extracted data and adverse events. We contacted study authors for additional information. We presented outcomes as pooled odds ratios (OR) with 95% confidence intervals (95% CI), based on random-effects models (inverse variance method). We analysed studies separately by surgical intervention, but pooled outcomes reported at different follow-up intervals. We compared our results to Bayesian and classical (frequentist) models. We investigated heterogeneity. We assessed the quality of evidence with GRADE.

MAIN RESULTS

In this updated review, we identified 40 new RCTs and seven ongoing studies. In total, we included 63 RCTs in the review, but we were only able to synthesize data on regional anaesthesia for the prevention of PPP beyond three months after surgery from 39 studies, enrolling a total of 3027 participants in our inclusive analysis.Evidence synthesis of seven RCTs favoured epidural anaesthesia for thoracotomy, suggesting the odds of having PPP three to 18 months following an epidural for thoracotomy were 0.52 compared to not having an epidural (OR 0.52 (95% CI 0.32 to 0.84, 499 participants, moderate-quality evidence). Simlarly, evidence synthesis of 18 RCTs favoured regional anaesthesia for the prevention of persistent pain three to 12 months after breast cancer surgery with an OR of 0.43 (95% CI 0.28 to 0.68, 1297 participants, low-quality evidence). Pooling data at three to 8 months after surgery from four RCTs favoured regional anaesthesia after caesarean section with an OR of 0.46, (95% CI 0.28 to 0.78; 551 participants, moderate-quality evidence). Evidence synthesis of three RCTs investigating continuous infusion with local anaesthetic for the prevention of PPP three to 55 months after iliac crest bone graft harvesting (ICBG) was inconclusive (OR 0.20, 95% CI 0.04 to 1.09; 123 participants, low-quality evidence). However, evidence synthesis of two RCTs also favoured the infusion of intravenous local anaesthetics for the prevention of PPP three to six months after breast cancer surgery with an OR of 0.24 (95% CI 0.08 to 0.69, 97 participants, moderate-quality evidence).We did not synthesize evidence for the surgical subgroups of limb amputation, hernia repair, cardiac surgery and laparotomy. We could not pool evidence for adverse effects because the included studies did not examine them systematically, and reported them sparsely. Clinical heterogeneity, attrition and sparse outcome data hampered evidence synthesis. High risk of bias from missing data and lack of blinding across a number of included studies reduced our confidence in the findings. Thus results must be interpreted with caution.

AUTHORS' CONCLUSIONS

We conclude that there is moderate-quality evidence that regional anaesthesia may reduce the risk of developing PPP after three to 18 months after thoracotomy and three to 12 months after caesarean section. There is low-quality evidence that regional anaesthesia may reduce the risk of developing PPP three to 12 months after breast cancer surgery. There is moderate evidence that intravenous infusion of local anaesthetics may reduce the risk of developing PPP three to six months after breast cancer surgery.Our conclusions are considerably weakened by the small size and number of studies, by performance bias, null bias, attrition and missing data. Larger, high-quality studies, including children, are needed. We caution that except for breast surgery, our evidence synthesis is based on only a few small studies. On a cautionary note, we cannot extend our conclusions to other surgical interventions or regional anaesthesia techniques, for example we cannot conclude that paravertebral block reduces the risk of PPP after thoracotomy. There are seven ongoing studies and 12 studies awaiting classification that may change the conclusions of the current review once they are published and incorporated.

Prevention and treatment of low back pain: evidence, challenges, and promising directions

Many clinical practice guidelines recommend similar approaches for the assessment and management of low back pain. Recommendations include use of a biopsychosocial framework to guide management with initial non-pharmacological treatment, including education that supports self-management and resumption of normal activities and exercise, and psychological programmes for those with persistent symptoms. Guidelines recommend prudent use of medication, imaging, and surgery. The recommendations are based on trials almost exclusively from high-income countries, focused mainly on treatments rather than on prevention, with limited data for cost-effectiveness. However, globally, gaps between evidence and practice exist, with limited use of recommended first-line treatments and inappropriately high use of imaging, rest, opioids, spinal injections, and surgery. Doing more of the same will not reduce back-related disability or its long-term consequences. The advances with the greatest potential are arguably those that align practice with the evidence, reduce the focus on spinal abnormalities, and ensure promotion of activity and function, including work participation. We have identified effective, promising, or emerging solutions that could offer new directions, but that need greater attention and further research to determine if they are appropriate for large-scale implementation. These potential solutions include focused strategies to implement best practice, the redesign of clinical pathways, integrated health and occupational interventions to reduce work disability, changes in compensation and disability claims policies, and public health and prevention strategies.

Reducing sedentary behaviour to decrease chronic low back pain: the stand back randomised trial

OBJECTIVE

The Stand Back study evaluated the feasibility and effects of a multicomponent intervention targeting reduced prolonged sitting and pain self-management in desk workers with chronic low back pain (LBP).

METHODS

This randomised controlled trial recruited 27 individuals with chronic LBP, Oswestry Disability Index (ODI) >10% and desk jobs (sitting ≥20 hours/week). Participants were randomised within strata of ODI (>10%-<20%, ≥20%) to receive bimonthly behavioural counselling (in-person and telephone), a sit-stand desk attachment, a wrist-worn activity-prompting device and cognitive behavioural therapy for LBP self-management or control. Self-reported work sitting time, visual analogue scales (VAS) for LBP and the ODI were assessed by monthly, online questionnaires and compared across intervention groups using linear mixed models.

RESULTS

Baseline mean (SD) age was 52 (11) years, 78% were women, and ODI was 24.1 (10.5)%. Across the 6-month follow-up in models adjusted for baseline value, work sitting time was 1.5 hour/day (P<0.001) lower comparing intervention to controls. Also across follow-up, ODI was on average 8 points lower in intervention versus control (P=0.001). At 6 months, the relative decrease in ODI from baseline was 50% in intervention and 14% in control (P=0.042). LBP from VAS was not significantly reduced in intervention versus control, though small-to-moderate effect sizes favouring the intervention were observed (Cohen's d ranged from 0.22 to 0.42).

CONCLUSION

An intervention coupling behavioural counselling targeting reduced sedentary behaviour and pain self-management is a translatable treatment strategy that shows promise for treating chronic LBP in desk-bound employees.

TRIAL REGISTRATION NUMBER

NCT0224687; Pre-results.

Local anaesthetics and regional anaesthesia versus conventional analgesia for preventing persistent postoperative pain in adults and children

BACKGROUND

Regional anaesthesia may reduce the rate of persistent postoperative pain (PPP), a frequent and debilitating condition. This review was originally published in 2012 and updated in 2017.

OBJECTIVES

To compare local anaesthetics and regional anaesthesia versus conventional analgesia for the prevention of PPP beyond three months in adults and children undergoing elective surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to December 2016 without any language restriction. We used a combination of free text search and controlled vocabulary search. We limited results to randomized controlled trials (RCTs). We updated this search in December 2017, but these results have not yet been incorporated in the review. We conducted a handsearch in reference lists of included studies, review articles and conference abstracts. We searched the PROSPERO systematic review registry for related systematic reviews.

SELECTION CRITERIA

We included RCTs comparing local or regional anaesthesia versus conventional analgesia with a pain outcome beyond three months after elective, non-orthopaedic surgery.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trial quality and extracted data and adverse events. We contacted study authors for additional information. We presented outcomes as pooled odds ratios (OR) with 95% confidence intervals (95% CI), based on random-effects models (inverse variance method). We analysed studies separately by surgical intervention, but pooled outcomes reported at different follow-up intervals. We compared our results to Bayesian and classical (frequentist) models. We investigated heterogeneity. We assessed the quality of evidence with GRADE.

MAIN RESULTS

In this updated review, we identified 40 new RCTs and seven ongoing studies. In total, we included 63 RCTs in the review, but we were only able to synthesize data on regional anaesthesia for the prevention of PPP beyond three months after surgery from 41 studies, enrolling a total of 3143 participants in our inclusive analysis.Evidence synthesis of seven RCTs favoured epidural anaesthesia for thoracotomy, suggesting the odds of having PPP three to 18 months following an epidural for thoracotomy were 0.52 compared to not having an epidural (OR 0.52 (95% CI 0.32 to 0.84, 499 participants, moderate-quality evidence). Simlarly, evidence synthesis of 18 RCTs favoured regional anaesthesia for the prevention of persistent pain three to 12 months after breast cancer surgery with an OR of 0.43 (95% CI 0.28 to 0.68, 1297 participants, low-quality evidence). Pooling data at three to 8 months after surgery from four RCTs favoured regional anaesthesia after caesarean section with an OR of 0.46, (95% CI 0.28 to 0.78; 551 participants, moderate-quality evidence). Evidence synthesis of three RCTs investigating continuous infusion with local anaesthetic for the prevention of PPP three to 55 months after iliac crest bone graft harvesting (ICBG) was inconclusive (OR 0.20, 95% CI 0.04 to 1.09; 123 participants, low-quality evidence). However, evidence synthesis of two RCTs also favoured the infusion of intravenous local anaesthetics for the prevention of PPP three to six months after breast cancer surgery with an OR of 0.24 (95% CI 0.08 to 0.69, 97 participants, moderate-quality evidence).We did not synthesize evidence for the surgical subgroups of limb amputation, hernia repair, cardiac surgery and laparotomy. We could not pool evidence for adverse effects because the included studies did not examine them systematically, and reported them sparsely. Clinical heterogeneity, attrition and sparse outcome data hampered evidence synthesis. High risk of bias from missing data and lack of blinding across a number of included studies reduced our confidence in the findings. Thus results must be interpreted with caution.

AUTHORS' CONCLUSIONS

We conclude that there is moderate-quality evidence that regional anaesthesia may reduce the risk of developing PPP after three to 18 months after thoracotomy and three to 12 months after caesarean section. There is low-quality evidence that regional anaesthesia may reduce the risk of developing PPP three to 12 months after breast cancer surgery. There is moderate evidence that intravenous infusion of local anaesthetics may reduce the risk of developing PPP three to six months after breast cancer surgery.Our conclusions are considerably weakened by the small size and number of studies, by performance bias, null bias, attrition and missing data. Larger, high-quality studies, including children, are needed. We caution that except for breast surgery, our evidence synthesis is based on only a few small studies. On a cautionary note, we cannot extend our conclusions to other surgical interventions or regional anaesthesia techniques, for example we cannot conclude that paravertebral block reduces the risk of PPP after thoracotomy. There are seven ongoing studies and 12 studies awaiting classification that may change the conclusions of the current review once they are published and incorporated.

Stress and Alterations in the Pain Matrix: A Biopsychosocial Perspective on Back Pain and Its Prevention and Treatment

The genesis of chronic pain is explained by a biopsychosocial model. It hypothesizes an interdependency between environmental and genetic factors provoking aberrant long-term changes in biological and psychological regulatory systems. Physiological effects of psychological and physical stressors may play a crucial role in these maladaptive processes. Specifically, long-term demands on the stress response system may moderate central pain processing and influence descending serotonergic and noradrenergic signals from the brainstem, regulating nociceptive processing at the spinal level. However, the underlying mechanisms of this pathophysiological interplay still remain unclear. This paper aims to shed light on possible pathways between physical (exercise) and psychological stress and the potential neurobiological consequences in the genesis and treatment of chronic pain, highlighting evolving concepts and promising research directions in the treatment of chronic pain. Two treatment forms (exercise and mindfulness-based stress reduction as exemplary therapies), their interaction, and the dose-response will be discussed in more detail, which might pave the way to a better understanding of alterations in the pain matrix and help to develop future prevention and therapeutic concepts.

The usefulness of interpectoral block as an analgesic technique in breast cancer surgery

OBJECTIVE

To compare the analgesic efficacy of continuous interpectoral block (CIPB) compared to intravenous analgesia (IV) after breast surgery.

MATERIAL AND METHOD

A prospective, comparative and randomised study of women aged from 18-75years, ASAI-III, operated for breast cancer. In group1 (CIPB) after general anaesthetic, an ultrasound-guided interpectoral catheter was placed and 30mL of 0.5% ropivacaine was administered through it. In the event of an increase in heart rate and blood pressure >15% after the surgical incision, intravenous fentanyl 1μg·kg^-1 was administered, repeating the dose as necessary. In the postoperative period, perfusion of ropivacaine 0.2% 5mL·h^-1; with PCA bolus 5mL/30minutes was administered through the catheter for 24hours and rescue analgesia prescribed with 5mg subcutaneous morphine chloride. In group2 (IV), after induction of general anaesthesia, intravenous fentanyl was administered in the same way as in the other group. The patients received metamizole 2g with dexketoprofen 50mg and ondansetron 4mg postoperatively followed by perfusion of metamizole 4%, tramadol 0.2% and ondansetron 0.08% 2ml·h^-1; with PCA bolus 2mL/20min for 24hours. The same rescue analgesia was prescribed. The principal variables recorded were pain at rest and during movement, according to a simple verbal scale (VAS 0-10) and the rescue analgesia required on discharge from recovery, at 12 and at 24hours.

RESULTS

137 patients were included: 81 in group1 (59.12%) and 56 in group2 (40.87%). No significant differences were observed in the analgesia between either group, but differences were observed in the dose of intraoperative fentanyl (P<.05). Differences that were not significant were observed in the rescue analgesia required on recovery (10% fewer on group1).

CONCLUSIONS

Both techniques provided effective postoperative analgesia, but the CIPB group required significantly less intraoperative fentanyl.

The curse of relieving pain

A 39-year-old woman with a history of chronic back pain due to spinal haemangiomas, multiple malignancies and depression was brought by Emergency medical servicesS to the emergency centre (EC) after being found unresponsive on the bathroom floor. The patient had an exacerbation of her back pain the previous day for which she admitted to taking double her usual dose of oxycodone, in addition to alprazolam, lorazepam, diphenhydramine and a glass of wine. She reported that she lost consciousness and was down for over 8 hours. In the EC, she complained of right forearm pain which was accompanied by mild diffuse soft-tissue swelling and decreased sensation in the right hand. Radial pulse was intact. Creatine kinase was found to be at 4663 U/L. The patient was found to have acute compartment syndrome and underwent emergent forearm fasciotomy. She eventually regained full function of the right arm.

Pregabalin versus placebo in targeting pro-nociceptive mechanisms to prevent chronic pain after whiplash injury in at-risk individuals - a feasibility study for a randomised controlled trial

BACKGROUND

Whiplash-associated disorders (WAD) are an enormous and costly burden to Australian society. Up to 50% of people who experience a whiplash injury will never fully recover. Whiplash is resistant to treatment and no early management approach has yet been shown to prevent chronic pain. The early presence of central sensitization is associated with poor recovery. Pregabalin's effects on central sensitization indicate the potential to prevent or modulate these processes after whiplash injury and to improve health outcomes, but this has not been investigated. This paper describes the protocol for a feasibility study for a randomised controlled trial of pregabalin plus evidence-based advice compared to placebo plus evidence-based advice for individuals with acute whiplash injury who are at risk of poor recovery.

METHODS

This double blind, placebo-controlled randomised feasibility study will examine the feasibility and potential effectiveness of pregabalin and evidence-based advice (intervention) compared to placebo and evidence-based advice (control) for individuals with acute whiplash injury at risk of poor recovery. Thirty participants (15 per group) aged 18-65 years with Grade II WAD, within 48 hours of injury and currently experiencing at least moderate pain (NRS: ≥ 5/10) will be recruited from Emergency Departments of public hospitals in Queensland, Australia. Pregabalin will be commenced at 75 mg bd and titrated up to 300 mg bd as tolerated for 4 weeks followed by 1 week of weaning.

RESULTS

The feasibility of trial procedures will be tested, as well as the potential effect of the intervention on the outcomes. The primary outcome of neck pain intensity at 3 months from randomisation will be compared between the treatment groups using standard analysis of variance techniques.

DISCUSSION

Feasibility and potential effectiveness data will inform an appropriately powered full trial, which if successful, will provide an effective and cost-effective intervention for a costly and treatment resistant condition. It will also have implications for the early management of other traumatic conditions beyond whiplash.

TRIAL REGISTRATION

Clinical Trials Primary Registry: Australian and New Zealand Clinical Trials Registry.

CLINICAL TRIAL REGISTRATION NUMBER

ACTRN12617000059369 . Date of Registration: 11/01/2017. Primary Trial Sponsor: The University of Queensland, Brisbane QLD 4072 Australia.

Acetaminophen reduces acute and persistent incisional pain after hysterectomy

OBJECTIVE

Acetaminophen is effective for acute surgical pain, but whether it reduces persistent incision pain remains unknown. We tested the primary hypothesis that patients given perioperative acetaminophen have less incisional pain three months after surgery. Our secondary hypotheses were that patients randomized to acetaminophen have less postoperative pain and analgesic consumption, and better functional recovery at three months.

METHODS

140 patients having abdominal hysterectomy were randomly assigned to: 1)intravenous acetaminophen (4 g/day for 72 postoperative hours); or, 2) saline placebo. The primary outcome was incisional pain visual analog scale (VAS) at three months after surgery. The secondary outcomes were (1, 2) postoperative VAS scores while laying and sitting and (3) total patient-controlled intravenous tramadol consumption during the initial 24 hours, (4) DN4 questionnaires and (5) SF-12 at three months after surgery.

RESULTS

The persistent incisional pain scores at three months were significantly lower in acetaminophen (median [Q1, Q3]: 0 [0, 0]) as compared with saline group (0 [0, 1]) (P = 0.002). Specifically, 89%, 9%, and 2% of acetaminophen patients with VAS pain score at three months of 0, 1, and 2 or more, as compared with 66%, 23%, and 10% in the saline group (odds ratio: 2.19 (95% CI: 1.33, 3.59), P = 0.002). Secondly, postoperative pain scores both laying and sitting were significantly lower in the acetaminophen group. Acetaminophen group had significantly better DN4 score and mental health related but not physical health related quality of life.

CONCLUSIONS

Our results suggest that acetaminophen reduces the risk and intensity of persistent incisional pain. However, there are other mechanisms by which acetaminophen might reduce persistent pain.

KEY WORDS

Anesthesia, acetaminophen, Persistent surgical pain, Postoperative acute pain.

Chronic Pain in the School Setting: The Teachers' Point of View

BACKGROUND

The aims of this study were to (1) examine the reactions of teachers and student teachers to children experiencing pain, (2) identify the most common challenges and potential resources that are associated to dealing with them, and (3) examine whether their responses differed as a function of their experience or sex.

METHODS

Forty teachers and 318 student teachers completed a survey which included descriptive information, a questionnaire that assesses different responses of participants to children who experience pain, and provides a list of problems and resources that participants might encounter and implement, respectively, when dealing with these children.

RESULTS

The study participants most often endorsed use of coping and health-promoting responses. Experienced teachers endorsed solicitous responses significantly more often than student teachers. Women reported responding more with solicitous responses than men. Absenteeism and the negative effect of pain on the ability of students to engage in school activities were the most common pain-related challenges mentioned by the study participants overall.

CONCLUSIONS

The findings emphasize (1) the need for developing guidelines to help teachers to help students experiencing chronic pain, and (2) the importance of including information about pediatric chronic pain in teachers training.

Patients with chronic pain may need extra support when prescribed physical activity in primary care: a qualitative study

BACKGROUND

Physical activity plays an important role in the prevention and treatment of chronic musculoskeletal pain, but chronic pain may implicate a poor rehabilitation outcome. The concept of physical activity on prescription (PAP) is a therapeutic option for various diseases, but there is a lack of knowledge about how patients with chronic musculoskeletal pain experience receiving the prescription.

OBJECTIVES

The objective of this study was to describe the experiences of and thoughts about receiving a prescription for physical activity of people with chronic musculoskeletal pain.

DESIGN

Interviews analysed using qualitative content analysis with an inductive approach.

SETTING

Three primary healthcare centres in a mixed rural and suburban area in the vicinity of a large city in western Sweden.

SUBJECTS

Fifteen individuals with chronic musculoskeletal pain.

RESULTS

Four categories were identified with the overarching theme "Physical activity in chronic pain requires extra support". There were several barriers for increasing activity level and these patients suffered from the additional burden of pain. The categories were: "Important to identify needs", "Barriers and facilitators for physical activity", "Perceptions of PAP vary" and "Effects found of receiving PAP".

CONCLUSIONS

Despite the many positive experiences of receiving PAP, patients described confusion about the role and execution of PAP. Chronic pain is an additional barrier for increasing activity level, and it is crucial to consider these patients' circumstances. This study suggests that patients with chronic musculoskeletal pain have a greater need for information and extra support to overcome existing barriers, before or when physical activity is prescribed. Key Points Physical activity is important for prevention and treatment of chronic pain and has earlier been shown to be increased by "physical activity on prescription". Patients with chronic musculoskeletal pain required the prescriber to listen and take the patients' circumstances, context, symptoms and current activity level into account to a greater extent. Patients with chronic musculoskeletal pain experienced more obstacles to increase their physical activity and, therefore, had a greater need for individually tailored information and support when prescribed physical activity. Patients with chronic musculoskeletal pain found it difficult to distinguish between physical activity on prescription and physiotherapy and perceived that also the physicians could not tell the difference.

Diagnosis and treatment of pelvic congestion syndrome: Single-centre experiences

BACKGROUND

One of the underestimated causes of chronic pelvic pain (CPP) in women may be pelvic congestion syndrome (PCS) that is defined as the presence of varicose of ovarian and pelvic veins associated with chronic pain in the region of the pelvis. This pain is present longer than 6 months and intensifies with prolonged standing, coitus and menstruation. The disease constitutes a diagnostic as well as therapeutic problem, thus posing a challenge for the clinician. Transcatheter ovarian vein embolization might be a safe and effective option for PCS treatment.

OBJECTIVES

The objective of this study was to evaluate the efficacy of ovarian vein embolization ovarian as a method of the PCS treatment.

MATERIAL AND METHODS

Between 2002-2012, 11 embolization procedures were performed in 10 women (age range: 34-43; median age 39) with the diagnosis of PCS. One patient underwent embolization procedure twice. In 1 case the combined therapy of endovascular embolization and surgical phlebectomy of vulvar varices was performed.

RESULTS

There were no major intrainterventional complications. In all the patients (100%) a significant improvement in the clinical status was noted. The procedure improved the quality of life in the patients. Three women (30%) had a mild recurrence of the symptoms at mid-term follow-up. Among 8 women who had complained of dyspareunia prior to embolization 6 patients reported complete pain relief, in other 2 cases the pain subsided partially. There was a significant decrease in the severity of symptoms associated with hemorrhoids.

CONCLUSIONS

We consider embolization of insufficient ovarian veins an effective and safe way of treatment in a well-selected group of patients with PCS.

Mesh fixation with glue versus suture for chronic pain and recurrence in Lichtenstein inguinal hernioplasty

BACKGROUND

Chronic pain following mesh-based inguinal hernia repair is frequently reported, and has a significant impact on quality of life. Whether mesh fixation with glue can reduce chronic pain without increasing the recurrence rate is still controversial.

OBJECTIVES

To determine whether tissue adhesives can reduce postoperative complications, especially chronic pain, with no increase in recurrence rate, compared with sutures for mesh fixation in Lichtenstein hernia repair.

SEARCH METHODS

We searched the following electronic databases with no language restrictions: the Cochrane Central Register of Controlled Trials (CENTRAL; issue 4, 2016) in the Cochrane Library (searched 11 May 2016), MEDLINE Ovid (1986 to 11 May 2016), Embase Ovid (1986 to 11 May 2016), Science Citation Index (Web of Science) (1986 to 11 May 2016), CBM (Chinese Biomedical Database), CNKI (China National Knowledge Infrastructure), VIP (a full-text database in China), Wanfang databases. We also checked reference lists of identified papers (included studies and relevant reviews).

SELECTION CRITERIA

We included all randomised and quasi-randomised controlled trials comparing glue versus sutures for mesh fixation in Lichtenstein hernia repair. Cluster-RCTs were also eligible.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data and assessed the risk of bias independently. Dichotomous outcomes were expressed as odds ratio (OR) with 95% confidence intervals (CI). Continuous outcomes were expressed as mean differences (MD) with 95% CIs.

MAIN RESULTS

Twelve trials with a total of 1932 participants were included in this review. The overall postoperative chronic pain in the glue group was reduced by 37% (OR 0.63, 95% CI 0.44 to 0.91; 10 studies, 1418 participants, low-quality evidence) compared with the suture group. However, the results changed when we conducted subgroup analysis with regard to the type of mesh. Subgroup analysis of included studies using lightweight mesh showed the reduction of chronic pain was less profound and insignificant (OR 0.77, 95% CI 0.50 to 1.17). Subgroup analysis of included studies using heavyweight mesh resulted in a significant benefit from the fixation with glue (OR 0.38, 95% CI 0.17 to 0.82).Hernia recurrence was similar between the two groups (OR 1.44, 95% CI 0.63 to 3.28; 12 studies, 1932 participants, low-quality evidence). Fixation with glue was superior to suture regarding duration of the operation (MD -3.13, 95% CI -4.48 to -1.78; 9 studies, 1790 participants, low-quality evidence); haematoma (OR 0.52, 95% CI 0.31 to 0.86; 10 studies, 1384 participants, moderate-quality evidence); and recovery time to daily activities (MD -1.26, 95% CI -1.89 to -0.63; 3 studies, 403 participants, low-quality evidence).We also investigated adverse events. There were no significant differences between the two groups. For superficial wound infection pooled analyses showed OR 1.23, 95% CI 0.37 to 4.11; 7 studies, 763 participants (low-quality evidence); for mesh/deep infection OR 0.67, 95% CI 0.16 to 2.83; 8 studies, 1393 participants (low-quality evidence). Furthermore, we investigated seroma (a postoperative swelling caused by fluid) (OR 0.83, 95% CI 0.51 to 1.33); and persisting numbness (OR 0.81, 95% CI 0.57 to 1.14).Finally, six trials involving 1009 participants reported postoperative length of stay, resulting in non-significant difference between the two groups (MD -0.12, 95% CI: -0.35 to 0.10)Due to the lack of data, it was impossible to draw any distinction between synthetic glue and biological glue.Eight out of 12 trials showed high risk of bias in at least one of the investigated domains. Two studies were quasi-randomised controlled trials and the allocation sequence of one trial was not concealed. Nearly half of the included trials either did not provide adequate information or had high risk of bias regarding blinding processes. The risk of bias for incomplete outcome data of all the included studies varied from low to high risk of bias. Two trials did not report on some important outcomes. One study was funded by the manufacturer producing the fibrin sealant. Therefore, according to the 'Summary of findings' tables, the quality of the evidence (GRADE) for the outcomes is moderate to low.

AUTHORS' CONCLUSIONS

Based on the short-term results, glue may reduce postoperative chronic pain and not simultaneously increase the recurrence rate, compared with sutures for mesh fixation in Lichtenstein hernia repair. Glue may therefore be a sensible alternative to suture for mesh fixation in Lichtenstein repair. Larger trials with longer follow-up and high quality are warranted. The difference between synthetic glue and biological glue should also be assessed in the future.

Antinociceptive activity and mechanism of action of hydroalcoholic extract and dichloromethane fraction of Amphilophium crucigerum seeds in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The medicinal plant generally known as monkey's comb (Amphilophium crucigerum) has been popularly described for the treatment of neuropathic and inflammatory pain, specially seeds preparations.

AIM OF THE STUDY

The goal of the present study was to evaluate the antinociceptive effect of the crude extract (Crd) and dichloromethane fraction (Dcm) of A. crucigerum seeds, and investigate the involvement of transient receptor potential vanilloid 1 (TRPV1) receptor in this effect.

MATERIALS AND METHODS

Male Swiss mice were used in this study. The effects of Crd and Dcm was tested on capsaicin-induced Ca²⁺ influx or the specific binding of [³H]-resiniferatoxin. Moreover, after treatment with Crd or Dcm, animals were exposed to acute pain (hot water tail-flick and capsaicin intraplantar test) or chronic pain models (injection of complete Freund's adjuvant or partial ligation of the sciatic nerve). Acute adverse effects were also noted: locomotor activity, corporal temperature, hepatic or renal damage, gastrointestinal transit alteration, and ulcerogenic activity.

RESULTS

The oral administration of Crd or Dcm resulted in an antinociceptive effect in the hot water tail-flick (48°C) and capsaicin intraplantar tests. Furthermore, these preparations exhibited antinociceptive and anti-inflammatory effects in a chronic inflammatory pain model, and antinociceptive effects in a neuropathic pain model. Moreover, Crd and Dcm reduced capsaicin-induced Ca²⁺ influx and diminished the [³H]-resiniferatoxin specific binding to spinal cord membranes. Acute adverse events were not found with Crd or Dcm administration.

CONCLUSION

In conclusion, our results support the analgesic effect of A. crucigerum and suggest the presence of compounds that may act as TRPV1 antagonists.

Quadratus lumborum block in chronic pain after abdominal hernia repair: case report

BACKGROUND AND OBJECTIVES

The quadratus lumborum blockade was described by R. Blanco in its two approaches (I and II). The local anesthetic deposition in this location can provide blockade to T6-L1 dermatomes. We performed this fascia blockade guided by ultrasound for treating a chronic neuropathic pain in the abdominal wall.

CASE REPORT

Male patient, 61 years old, 83kg, with a history of thrombocytopenia due to alcoholic cirrhosis, among others; had chronic pain in the abdominal wall after multiple abdominal hernia repairs in the last year and a half, with poor response to treatment with neuromodulators and opioids. On clinical examination, he revealed a neuropathic pain, with prevalence of allodynia to touch, covering the entire anterior abdominal wall, from T7 to T12 dermatomes. We opted for a quadratus lumborum block type II, guided by ultrasound, with administration of 0.2% ropivacaine (25mL) and depot (vial) methylprednisolone (20mg) on each side. The procedure gave immediate relief of symptoms and, after six months, the patient still had a significant reduction in allodynia without compromising the quality of life.

CONCLUSIONS

We consider that performing the quadratus lumborum block type II was an important analgesic option in the treatment of a patient with chronic pain after abdominal hernia repair, emphasizing the effects of local anesthetic spread to the thoracic paravertebral space. The technique has proven to be safe and well tolerated. The publication of more clinical cases reporting the effectiveness of this blockade for chronic pain is desirable.

Efficacy of whole-course pain intervention on health-related quality of life for patients after esophagectomy

PURPOSE

The purpose of this study was to evaluate the efficacy of whole-course pain intervention on health-related quality of life (QoL) for patients after esophagectomy.

METHODS

A retrospecitve analysis was performed on 81 patients who were enrolled as conventional care group (control group with 40 cases) and whole-course pain intervention group (observation group with 41 cases) respectively af?ter Sweet, Ivor-Lewis and McKeown esophagectomy between January 2011 and December 2013. Then, the postoperative recovery parameters of the patients were compared, accompanied with evaluation of QoL using the 36-Item Short Form Health Survey 6 months after the operation.

RESULTS

The patients in the observation group demonstrated significantly better pain control and overall satisfaction rate than those of the control group, along with significantly lower morbidity of chronic postsurgical pain (CPSP) (p<0.05). However, the health-related QoL 6 months after the operation indicated no significant difference between the two groups (p>0.05).

CONCLUSION

In summary, the whole-course pain intervention is conducive to relieve pain and to reduce the occurrence of CPSP in patients after esophagectomy.

Polyunsaturated Fatty Acids and Chronic Pain: A Systematic Review and Meta-analysis

BACKGROUND

Chronic pain is one of the most frequent disease symptoms and represents a global health problem with a considerable economic burden. The role of polyunsaturated fatty acids (PUFA) in chronic pain conditions was debated during the last decade with conflicting results.

OBJECTIVE

To assess whether polyunsaturated fatty acids intake is useful as a preventive or curative tool in chronic pain.

STUDY DESIGN

Systematic review and meta-analysis.

SETTING

This study examined all published studies, either preventive or curative, on PUFA supplementation and chronic pain.

METHODS

We retrieved studies published in any language by searching systematically Medline, Embase, Conference Proceedings Citation Index, dissertations databases, and the 5 regional bibliographic databases of the World Health Organization until May 2015. We included both observational and intervention studies reporting effect measures and their confidence intervals of polyunsaturated fatty acids intake in the regular diet or supplementation and pain. Two investigators selected studies; extracted data independently on baseline characteristics, exposure, and outcomes; and rated the quality of interventional studies using Jadad score. We calculated pooled standardized mean differences (SMDs) of pain indexes such as the Visual Analogue Score. We further carried out subgroup analyses by disease, type of PUFA, outcome scale, quality index, dose, and time of supplementation.

RESULTS

We retrieved 5 observational and 46 intervention studies. Only one observational study showed a protective effect of PUFA. On the contrary, the interventional studies yielded a pooled random effects SMD of -0.40 (95% CI -0.58, -0.22), which indicates improvement, as 0 is the value that indicates absence of effect. The largest effect was found for dysmenorrhea (SMD -0.82, 95% CI -1.21, -0.43), Ω-3 supplementation (-0.47, 95% CI -0.68, -0.26) and composite scores (-0.58, 95% CI -1.07, -0.09). Mitigation of pain was stronger for low doses (-0.55, 95% CI -0.79, -0.30) and short supplementation periods (-0.56, 95% CI -0.86, -0.25).

LIMITATIONS

While the number of curative studies was large, that of preventive studies available was limited.

CONCLUSION

Our results suggest that Ω-3 PUFA supplementation moderately improves chronic pain, mainly that due to dysmenorrhea. Further investigation on the preventive potential of PUFA supplementation is needed, as the amount of evidence is scarce. Key words: Meta-analysis, systematic review, chronic pain, PUFA, supplementation, Ω-3, dysmenorrhea.

Comparing two sampling methods to engage hard-to-reach communities in research priority setting

BACKGROUND

Effective community-partnered and patient-centered outcomes research needs to address community priorities. However, optimal sampling methods to engage stakeholders from hard-to-reach, vulnerable communities to generate research priorities have not been identified.

METHODS

In two similar rural, largely Hispanic communities, a community advisory board guided recruitment of stakeholders affected by chronic pain using a different method in each community: 1) snowball sampling, a chain- referral method or 2) purposive sampling to recruit diverse stakeholders. In both communities, three groups of stakeholders attended a series of three facilitated meetings to orient, brainstorm, and prioritize ideas (9 meetings/community). Using mixed methods analysis, we compared stakeholder recruitment and retention as well as priorities from both communities' stakeholders on mean ratings of their ideas based on importance and feasibility for implementation in their community.

RESULTS

Of 65 eligible stakeholders in one community recruited by snowball sampling, 55 (85 %) consented, 52 (95 %) attended the first meeting, and 36 (65 %) attended all 3 meetings. In the second community, the purposive sampling method was supplemented by convenience sampling to increase recruitment. Of 69 stakeholders recruited by this combined strategy, 62 (90 %) consented, 36 (58 %) attended the first meeting, and 26 (42 %) attended all 3 meetings. Snowball sampling recruited more Hispanics and disabled persons (all P < 0.05). Despite differing recruitment strategies, stakeholders from the two communities identified largely similar ideas for research, focusing on non-pharmacologic interventions for management of chronic pain. Ratings on importance and feasibility for community implementation differed only on the importance of massage services (P = 0.045) which was higher for the purposive/convenience sampling group and for city improvements/transportation services (P = 0.004) which was higher for the snowball sampling group.

CONCLUSIONS

In each of the two similar hard-to-reach communities, a community advisory board partnered with researchers to implement a different sampling method to recruit stakeholders. The snowball sampling method achieved greater participation with more Hispanics but also more individuals with disabilities than a purposive-convenience sampling method. However, priorities for research on chronic pain from both stakeholder groups were similar. Although utilizing a snowball sampling method appears to be superior, further research is needed on implementation costs and resources.

Docking, characterization and investigation of β-cyclodextrin complexed with citronellal, a monoterpene present in the essential oil of Cymbopogon species, as an anti-hyperalgesic agent in chronic muscle pain model

BACKGROUND

Citronellal (CT) is a monoterpene with antinociceptive acute effect. β-Cyclodextrin (βCD) has enhanced the analgesic effect of various substances.

HYPOTHESIS/PURPOSE

To evaluate the effect of CT both complexed in β-cyclodextrin (CT-βCD) and non-complexed, in a chronic muscle pain model (CMP) in mice.

STUDY DESIGN

The complex containing CT in βCD was obtained and characterized in the laboratory. The anti-hyperalgesic effect of CT and CT-βCD was evaluated in a pre-clinical in vivo study in a murine CMP.

METHODS

The complex was characterized through differential scanning calorimetry, derivative thermogravimetry, moisture determination, infrared spectroscopy and scanning electron microscopy. Male Swiss mice were pre-treated with CT (50mg/kg, po), CT-βCD (50mg/kg, po), vehicle (isotonic saline, po) or standard drug (tramadol4 mg/kg, ip). 60 min after the treatment and then each 1h, the mechanic hyperalgesia was evaluated to obtain the time effect. In addition, the muscle strength using grip strength meter and hyperalgesia were also performed daily, for 7 days. We assessed by immunofluorescence for Fos protein on brains and spinal cords of mice. The involvement of the CT with the glutamatergic system was studied with molecular docking.

RESULTS

All characterization methods showed the CT-βCD complexation. CT-induced anti-hyperalgesic effect lasted until 6h (p <0.001) while CT-βCD lasted until 8h (p <0.001vs vehicle and p <0.001vs CT from the 6th h). CT-βCD reduced mechanical hyperalgesia on all days of treatment (p <0.05), without changing muscle strength. Periaqueductal gray (p <0.01) and rostroventromedular area (p <0.05) showed significant increase in the Fos protein expression while in the spinal cord, there was a reduction (p <0.001). CT showed favorable energy binding (-5.6 and -6.1) to GluR2-S1S2J protein based in the docking score function.

CONCLUSION

We can suggest that βCD improved the anti-hyperalgesic effect of CT, and that effect seems to involve the descending pain-inhibitory mechanisms, with a possible interaction of the glutamate receptors, which are considered as promising molecules for the management of chronic pain such as CMP.

Systemic TAK-242 prevents intrathecal LPS evoked hyperalgesia in male, but not female mice and prevents delayed allodynia following intraplantar formalin in both male and female mice: The role of TLR4 in the evolution of a persistent pain state

OBJECTIVE

Pain resulting from local tissue injury or inflammation typically resolves with time. Frequently, however, this pain may unexpectedly persist, becoming a pathological chronic state. Increasingly, the innate and adaptive immune systems are being implicated in the initiation and maintenance of these persistent conditions. In particular, Toll-like receptor 4 (TLR4) signaling has been shown to mediate the transition to a persistent pain state in a sex-dependent manner. In the present work, we explored this contribution using the TLR4 antagonist, TAK-242.

METHODS

Male and female C57Bl/6 mice were given intravenous (IV), intrathecal (IT), or intraperitoneal (IP) TAK-242 prior to IT delivery of lipopolysaccharide (LPS), and tactile reactivity was assessed at regular intervals over 72-h. Additional groups of mice were treated with IP TAK-242 prior to intraplantar formalin, and flinching was monitored for 1-h. Tactile reactivity was assessed at 7-days after formalin delivery.

RESULTS

LPS evoked TNF release from male and female macrophages and RAW267.4 cells, which was blocked in a concentration dependent fashion by TAK-242. In vivo, IT LPS evoked tactile allodynia to a greater degree in male than female mice. TAK-242, given by all routes, prevented development of IT LPS-induced tactile allodynia in male animals, but did not reverse their established allodynia. TLR4 deficiency and TAK-242 treatment attenuated IT LPS-induced allodynia in male, but not female mice. In the formalin model, pre-treatment with TAK-242 did not affect Phase 1 or Phase 2 flinching, but prevented the delayed tactile allodynia in both male and unexpectedly in female mice (Phase 3).

CONCLUSIONS

Together, these results suggest that TAK-242 is a TLR4 antagonist that has efficacy after systemic and intrathecal delivery and confirms the role of endogenous TLR4 signaling in triggering the development of a delayed allodynia in both male and female mice.