The gut microbiota in persistent post-operative pain following breast cancer surgery

Persistent post-surgical pain (PPSP) is defined as pain which continues after a surgical operation in a significant form for at least three months (and is not related to pre-existing painful conditions). PPSP is a common, under-recognised, and important clinical problem which affects millions of patients worldwide. Preventative measures which are currently available include the selection of a minimally invasive surgical technique and an aggressive multimodal perioperative analgesic regimen. More recently, a role for the gut microbiota in pain modulation has become increasingly apparent. This study aims to investigate any relationship between the gut microbiota and PPSP. A prospective observational study of 68 female adult patients undergoing surgery for management of breast cancer was carried out. Stool samples from 45 of these patients were obtained to analyse the composition of the gut microbiota. Measures of pain and state-trait anxiety were also taken to investigate further dimensions in any relationship between the gut microbiota and PPSP. At 12 weeks postoperatively, 21 patients (51.2%) did not have any pain and 20 patients (48.8%) reported feeling pain that persisted at that time. Analysis of the gut microbiota revealed significantly lower alpha diversity (using three measures) in those patients reporting severe pain at the 60 min post-operative and the 12 weeks post-operative timepoints. A cluster of taxa represented by Bifidobacterium longum, and Faecalibacterium prausnitzii was closely associated with those individuals reporting no pain at 12 weeks postoperatively, while Megamonas hypermegale, Bacteroides pectinophilus, Ruminococcus bromii, and Roseburia hominis clustered relatively closely in the group of patients fulfilling the criteria for persistent post-operative pain. We report for the first time specific associations between the gut microbiota composition and the presence or absence of PPSP. This may provide further insights into mechanisms behind the role of the gut microbiota in the development of PPSP and could inform future treatment strategies.

Virtual Reality in Acute and Chronic Pain Medicine: An Updated Review

PURPOSE OF REVIEW

This review critically analyzes the recent literature on virtual reality's (VR) use in acute and chronic pain management, offering insights into its efficacy, applications, and limitations.

RECENT FINDINGS

Recent studies, including meta-analyses and randomized controlled trials, have demonstrated VR's effectiveness in reducing pain intensity in various acute pain scenarios, such as procedural/acute pain and in chronic pain conditions. The role of factors such as immersion and presence in enhancing VR's efficacy has been emphasized. Further benefits have been identified in the use of VR for assessment as well as symptom gathering through conversational avatars. However, studies are limited, and strong conclusions will require further investigation. VR is emerging as a promising non-pharmacological intervention in pain management for acute and chronic pain. However, its long-term efficacy, particularly in chronic pain management, remains an area requiring further research. Key findings highlight that VR programs vary in efficacy depending on the specificity of the origin of pain.

Are we educating patients about postoperative analgesics following orthopaedic surgery? A scoping review

OBJECTIVES

To identify interventions educating patients undergoing orthopaedic surgery about postoperative analgesics and explore their associated outcomes.

METHODS

A scoping review using six databases was conducted. Eligible interventions were delivered to adult patients undergoing open orthopaedic procedures that could be feasibly implemented into any setting. Content, delivery methods and outcomes for interventions were described where available.

RESULTS

Eleven studies were included. Content and delivery methods differed substantially. Eight studies aimed to reduce postoperative harm by reducing opioid consumption. Studies also explored pain control (n = 6) and patient satisfaction (n = 4). Health literacy was not assessed in any study. Previous surgical or analgesic experience was infrequently reported.

CONCLUSION

This is the first scoping review assessing globally adaptable interventions designed to educate orthopaedic patients about postoperative analgesics. A paucity of interventions was found, with a limited range of patient-centred outcomes assessed. Further research is required. Co-designed educational materials with patients is recommended.

PRACTICE IMPLICATIONS

Despite the unclear benefit, clinicians should consider providing postoperative analgesic education to patients. Well-designed education has the potential to improve quality of life at low cost with low risk. Educational material adapted to local health literacy levels and prior surgical and analgesic experience is recommended to maximise engagement and impact.

The incidence of post cholecystectomy pain (PCP) syndrome at 12 months following laparoscopic cholecystectomy: a prospective evaluation in 200 patients

OBJECTIVES

Post cholecystectomy pain syndrome can cause significant distress, impairs quality of life and exacerbations often result in emergency visits. Poorly controlled postoperative pain is a recognized cause of persistent postsurgical pain. Abdominal myofascial pain syndrome is an underdiagnosed cause of persistent pain in this cohort. The objective was to estimate the incidence of poorly controlled postoperative pain in the first 48 h after surgery and the likelihood of developing persistent pain at 12 months.

METHODS

The patients undergoing laparoscopic cholecystectomy at a tertiary unit were consented for participation in a prospective service evaluation. A telephone review was performed at three, six and twelve months after surgery. Incidence of poorly controlled pain in the first 48 h after surgery was assessed. Patients with persistent pain were referred to the pain clinic.

RESULTS

Over a six-month period, 200 patients were assessed. Eleven patients were excluded (5.5 %). Twelve patients were lost to follow-up (6.6 %, 12/189). Patient satisfaction with acute postoperative pain management was low in 40 % (76/189). Poorly controlled postoperative pain was reported by 36 % (68/189) of patients. Incidence of persistent pain was 29 % (54/189) at 12 months post-surgery. Over half of patients with persistent pain (63 %, 34/54) reported poorly controlled postoperative pain. A somatic source was diagnosed in 54 % (29/54) with post cholecystectomy pain syndrome.

CONCLUSIONS

Poorly controlled postoperative pain was reported by a third of patients. Persistent pain was present in 29 % at twelve months post-surgery. Abdominal myofascial pain syndrome should be considered as a differential diagnosis in post cholecystectomy pain syndrome.

Interventional pathway in the management of refractory post cholecystectomy pain (PCP) syndrome: a 6-year prospective audit in 60 patients

OBJECTIVES

Post cholecystectomy pain syndrome can affect over a third of patients undergoing laparoscopic cholecystectomy. Acute exacerbations can result in recurrent emergency admission with excessive healthcare utilization. Standard surgical management appears to focus on visceral aetiology. Abdominal myofascial pain syndrome is a poorly recognised somatic pathology that can cause refractory pain in this cohort. It develops as a result of trigger points in the abdominal musculature. The report describes the pathophysiology and a novel interventional pathway in the management of post cholecystectomy pain secondary to abdominal myofascial pain syndrome.

METHODS

The prospective longitudinal audit was performed at a tertiary pain medicine clinic in a university teaching hospital. Over a six-year period, adult patients with refractory abdominal pain following laparoscopic cholecystectomy were included in a structured interventional management pathway. The pathway included two interventions. Intervention I was a combination of abdominal plane blocks and epigastric port site trigger injection with steroids. Patients who failed to report durable relief (>50% pain relief at 12 weeks) were offered pulsed radiofrequency treatment to the abdominal planes (Intervention II). Outcomes included patient satisfaction, change in opioid consumption and impact on emergency visits.

RESULTS

Sixty patients who failed to respond to standard management were offered the pathway. Four patients refused due to needle phobia. Fifty-six patients received Intervention I. Failure rate was 14% (8/56). Forty-eight patients (48/56, 86%) reported significant benefit at 12 weeks while 38 patients reported durable relief at 24 weeks (38/56, 68%). Nine patients received Intervention II and all (100%) reported durable relief. Emergency admissions and opioid consumption were reduced.

CONCLUSIONS

Abdominal myofascial pain syndrome is a poorly recognised cause of post cholecystectomy pain. The novel interventional management pathway could be an effective solution in patients who fail to benefit from standard management.

STING-IFN-I pathway relieves incision induced acute postoperative pain via inhibiting the neuroinflammation in dorsal root ganglion of rats

BACKGROUND

The purpose of this study was to study the effect of STING-IFN-I pathway on incision induced postoperative pain in rats and its possible mechanisms.

METHODS

The pain thresholds were evaluated by measuring the mechanical withdrawal threshold and the thermal withdrawal latency. The satellite glial cell and macrophage of DRG were analyzed. The expression of STING, IFN-a, P-P65, iNOS, TNF-α, IL-1β and IL-6 in DRG was evaluated.

RESULTS

The activation of STING-IFN-I pathway can reduce the mechanical hyperalgesia, thermal hyperalgesia, down-regulate the expression of P-P65, iNOS, TNF-α, IL-1β and IL-6, and inhibit the activation of satellite glial cell and macrophage in DRG.

CONCLUSIONS

The activation of STING-IFN-I pathway can alleviate incision induced acute postoperative pain by inhibiting the activation of satellite glial cell and macrophage, which reducing the corresponding neuroinflammation in DRG.

Protocol for Development and Validation of Multivariable Prediction Models for Chronic Postsurgical Pain Following Video-Assisted Thoracic Surgery

Purpose

Chronic postsurgical pain (CPSP) is a common complication after thoracic surgery and associated with long-term adverse outcomes. This study aims to develop two prediction models for CPSP after video-assisted thoracic surgery (VATS).

Methods and Analysis

This single-center prospective cohort study will include a total of 500 adult patients undergoing VATS lung resection (n = 350 for development and n = 150 for external validation). Patients will be enrolled continuously at The First Affiliated Hospital of Soochow University in Suzhou, China. The cohort for external validation will be recruited in another time period. The outcome is CPSP, which is defined as pain with the numerical rating scale score of 1 or higher 3 months after VATS. Univariate and multivariable logistic regression analyses will be performed to develop two CPSP prediction models based on patients' data of postoperative day 1 and day 14, respectively. For internal validation, we will use the bootstrapping validation technique. For external validation, the discrimination capability of the models will be assessed using the area under the receiver operating characteristic curve, and the calibration will be evaluated using the calibration curve and Hosmer-Lemeshow goodness-of-fit statistic. The results will be presented in model formulas and nomograms.

Conclusion

Based on the development and validation of the prediction models, our results contribute to early prediction and treatment of CPSP after VATS.

Trial Registration

Chinese Clinical Trial Register (ChiCTR2200066122).

Efficacy of perioperative gabapentin use in patients with idiopathic scoliosis undergoing fusion surgery: a systematic review and meta-analysis

PURPOSE

This study aimed to assess whether the perioperative use of gabapentin was associated with decreased opioid use.

METHODS

A meta-analysis was performed using PubMed, Embase, Scopus, and Cochrane Library. The randomized clinical trials included were focused on patients with adolescent idiopathic scoliosis who underwent posterior fusion surgery and were treated with gabapentin versus placebo medicine. The primary outcomes were opioid consumption at 24, 48, 72, and 96 h; time to introduction of oral medication, length of hospital stay, and period of urinary catheterization were also recorded. Data were combined using the Review Manager 5.4 software.

RESULTS

Four randomized clinical trials with a pool of 196 adolescent patients (mean age: 14.8 ± 2.0 years) were included. At 24 and 48 h after surgery, opioid consumption was significantly lower in the gabapentin group: (standardized mean difference [SMD]: -0.50; 95% confidence interval [CI] - 0.79 to - 0.22) and (SMD: - 0.59; 95% CI - 0.88 to - 0.30), respectively. At 72 and 96 h, there were no significant differences between studies: (SMD: - 0.19; 95% CI - 0.52 to 0.13) and (SMD: 0.12; 95% CI - 0.25 to 0.50), respectively. Regarding the administration type, there were significant differences in favor of the 15 mg/kg subgroup with 600 mg at 48 h (SMD: - 0.69; 95% CI - 1.08 to - 0.30). There were no significant differences concerning the time to introduction of oral medication (MD: - 0.08; 95% CI - 0.39 to 0.23), hospitalization time (MD: - 0.12; 95% CI - 0.40 to 0.16), or period of urinary catheterization (SMD: - 0.27; 95% CI - 0.58 to 0.05).

CONCLUSIONS

Gabapentin decreased opioid consumption during the first 48 h. Doses of 15 mg/kg showed superiority in reducing opioid consumption in the first 48 h.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Ocular Pain after Refractive Surgery: Interim Analysis of Frequency and Risk Factors

PURPOSE

To examine the frequency and risk factors for ocular pain after laser assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

DESIGN

Prospective study of individuals undergoing refractive surgery at 2 different centers.

PARTICIPANTS

One hundred nine individuals undergoing refractive surgery: 87% LASIK and 13% PRK.

METHODS

Participants rated ocular pain on a numerical rating scale (NRS) of 0 to 10 before surgery and 1 day, 3 months, and 6 months after surgery. A clinical examination focused on ocular surface health was performed 3 and 6 months after surgery. Persistent ocular pain was defined as an NRS score of 3 or more at both 3 and 6 months after surgery (patients), and this group was compared with individuals with NRS scores of < 3 at both time points (control participants).

MAIN OUTCOME MEASURES

Individuals with persistent ocular pain after refractive surgery.

RESULTS

The 109 patients who underwent refractive surgery were followed up for 6 months after surgery. Mean age was 34 ± 8 years (range, 23-57 years); 62% self-identified as female, 81% as White, and 33% as Hispanic. Eight patients (7%) reported ocular pain (NRS score ≥ 3) before surgery, with the frequency of ocular pain increasing after surgery to 23% (n = 25) at 3 months and 24% (n = 26) at 6 months. Twelve patients (11%) reported an NRS score of 3 or more at both time points and constituted the persistent pain group. Factors that predicted persistent pain after surgery in a multivariable analysis were (1) ocular pain before surgery predicated persistent pain after surgery (odds ratio [OR], 1.87; 95% confidence interval [CI], 1.06-3.31), (2) symptom report of depression before surgery (Patient Health Questionnaire-9: OR, 1.3; 95% CI, 1.1-1.6; P = 0.01), (3) use of an oral antiallergy medication before surgery (OR, 13.6; 95% CI, 2.1-89.3; P = 0.007), and (4) pain intensity day 1 after surgery (OR, 1.6; 95% CI, 1.2-2.2; P = 0.005). There were no significant associations between ocular surface signs of tear dysfunction and ocular pain, P > 0.05 for all ocular surface signs. Most individuals (> 90%) were completely or somewhat satisfied with their vision at 3 and 6 months.

CONCLUSIONS

Eleven percent of individuals reported persistent ocular pain after refractive surgery, with several preoperative and perioperative factors predicting pain after surgery.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

A prospective study of chronic postsurgical pain in elderly patients: incidence, characteristics and risk factors

BACKGROUND

Due to the continued growth of surgical procedures in older adults and the significant impact of chronic postsurgical pain (CPSP), it is crucial to improve our understanding of the occurrence of CPSP as well as the appropriate prevention and treatment. We therefore conducted this study to determine the incidence, characteristics and risk factors of CPSP in elderly patients at both 3 and 6 months after surgery.

METHODS

Elderly patients (aged ≥ 60 years) undergoing elective surgery in our institution between April 2018 and March 2020 were prospectively enrolled in this study. Data on demographics, preoperative psychological well-being, intraoperative surgical and anesthesia management, and acute postoperative pain intensity were collected. At 3 and 6 months after surgery, patients received telephone interview and completed the questionnaires regarding chronic pain characteristics, analgesic consumption, and interference of the pain with activities of daily living (ADL).

RESULTS

A total of 1065 elderly patients were followed up for 6 postoperative months and included in final analysis. At 3 and 6 months after operation, the incidence of CPSP was 35.6% [95% confidence interval (95% CI) 32.7 - 38.8%] and 21.5% (95% CI 19.0% - 23.9%), respectively. CPSP cause negative impacts on patient's ADL and most particularly on mood. Neuropathic features were found in 45.1% of the patients with CPSP at 3 months. At 6 months, 31.0% of those with CPSP reported that the pain had neuropathic features. Preoperative anxiety [3 months: Odds ratio (OR) 2.244, 95% CI 1.693 to 2.973; 6 months: OR 2.397, 95% CI 1.745 to 3.294], preoperative depression (3 months: OR 1.709, 95% CI 1.292 to 2.261; 6 months: OR 1.565, 95% CI 1.136-2.156), orthopedic surgery (3 months: OR 1.927, 95% CI 1.112 to 3.341; 6 months: OR 2.484, 95% CI 1.220 to 5.061), higher pain severity on movement within postoperative 24 h (3 months: OR 1.317, 95% CI 1.191 to 1.457; 6 months: OR 1.317, 95% CI 1.177 to 1.475) were associated with a higher risk for CPSP independently at both 3 and 6 months after surgery.

CONCLUSIONS

CPSP is a common postoperative complication in elderly surgical patients. Preoperative anxiety and depression, orthopedic surgery, and greater intensity of acute postoperative pain on movement are associated with an increased risk for CPSP. It should be kept in mind that developing psychological interventions to reduce anxiety and depression and optimizing the management of acute postoperative pain will be effective in reducing the development of CPSP in this population.

Sarcopenia is associated with an increase in long-term use of analgesics after elective surgery under general anesthesia

PURPOSE

To elucidate the association of presurgical sarcopenia and long-term non-opioid analgesic and opioid use after elective surgery under general anesthesia.

METHODS

We conducted this population-based propensity score matched to investigate the effects of sarcopenia and long-term non-opioid analgesic and opioid use after elective surgery under general anesthesia between 1 October 2016 and 31 December 2019 from Taiwan's National Health Insurance Research Database. Sarcopenia is a disease and coded as M62.84 in the International Classification of Diseases, 10th Revision, Clinical Modification. The primary outcome was the combined rate of the long-term use of all non-opioid analgesics or opioids over 3 and 6 months after elective surgery. By performing a logistic regression analysis, we calculated the adjusted ORs (aORs) with 95% CIs to identify the independent predictors for long-term non-opioid analgesic and opioid use after surgery.

RESULTS

In total, 2860 patients underwent elective surgery. The 3-month non-opioid analgesic and opioid use rates were respectively 49.7% and 1.8% in the sarcopenia group and 37.9% and 0.9% in the non-sarcopenia group; by contrast, 6-month non-opioid analgesic and opioid use rates were respectively 31.6% and 1.2% in the sarcopenia group and 17.2% and 0.3% in the non-sarcopenia group. Moreover, presurgical sarcopenia increased the risk of long-term non-opioid analgesic and opioid use after elective surgery under general anesthesia (aORs for non-opioid analgesic use over 3 and 6 months after surgery: 1.17 (95% CI 1.05 to 2.23) and 1.26 (95% CI 1.04 to 1.45), respectively; aORs for opioid use over 3 and 6 months after surgery: 1.17 (95% CI 1.07 to 2.21) and 1.23 (95% CI 1.10 to 3.64), respectively).

CONCLUSION

Sarcopenia is associated with higher rates of long-term non-opioid analgesic and opioid use after elective surgery under general anesthesia.

SUMMARY

The aim of this study was to compare the long-term use of non-opioid analgesics and opioids after elective surgery under general anesthesia between patients with and without sarcopenia. Results suggest that patients with sarcopenia are more likely to have increased use of non-opioid analgesics and opioids after surgery. Further research is needed to determine if sarcopenia can be modified prior to surgery and if this impacts the need for long-term pain management with these medications.

Perioperative opioids: a narrative review contextualising new avenues to improve prescribing

Opioids have dominated the management of perioperative pain in recent decades with higher doses than ever before used in some circumstances. Through the expanding use of opioids, growing research has highlighted their associated side-effects and the intertwined phenomena of acute withdrawal syndrome, opioid tolerance, and opioid-induced hyperalgesia. With multiple clinical guidelines now endorsing multimodal analgesia, a diverse array of opioid-sparing agents emerges and has been studied to variable degrees, including techniques of opioid-free anaesthesia. It remains unclear to what extent such methods should be adopted, yet current evidence does suggest dependence on opioids as the primary perioperative analgesic might not meet the principles of 'rational prescribing' as described by Maxwell. In this narrative review we describe how, using current evidence, a patient-centred rational-prescribing approach can be applied to opioids in the perioperative period. To contextualise this approach, we discuss the historical adoption of opioids in anaesthesia, our growing understanding of associated side-effects and emerging strategies of opioid-sparing and opioid-free anaesthesia. We discuss avenues and challenges for improving opioid prescribing to limit persistent postoperative opioid use and how these may be incorporated into a rational-prescribing approach.

The Role of Regional Anesthesia in the Development of Chronic Pain: a Review of Literature

Purpose of Review

The acute management of pain using regional anesthesia techniques may prevent the development of persistent postsurgical pain (PPP), ultimately improving patient outcomes and enhancing overall quality of life in postsurgical patients. The purpose of this review is to describe the current literature regarding the role of regional anesthesia techniques in the perioperative setting to address and prevent PPP.

Recent Findings

Data was collected and analyzed using results from randomized controlled studies stratified into categories based on different surgical subspecialties. Conclusions were drawn from each surgical category regarding the role of regional anesthesia and/or local analgesia in acute and chronic pain management on the long-term results seen in the studies analyzed.

Summary

Preoperative consultations and optimized perioperative analgesia using regional anesthesia and local analgesia play a fundamental role preventing and treating postoperative pain after many types of surgery by managing pain in the acute setting to mitigate the future development of PPP. Additional studies in different surgical subspecialties are needed to confirm the role regional anesthesia plays in chronic postsurgical pain (CPSP) prevention.

Epigenetic Mechanisms of Neural Plasticity in Chronic Neuropathic Pain

Neuropathic pain is a challenging clinical problem and remains difficult to treat. Altered gene expression in peripheral sensory nerves and neurons due to nerve injury is well documented and contributes critically to the synaptic plasticity in the spinal cord and the initiation and maintenance of chronic pain. However, our understanding of the epigenetic mechanisms regulating the transcription of pro-nociceptive (e.g., NMDA receptors and α2δ-1) and antinociceptive (e.g., potassium channels and opioid and cannabinoid receptors) genes are still limited. In this review, we summarize recent studies determining the roles of histone modifications (including methylation, acetylation, and ubiquitination), DNA methylation, and noncoding RNAs in neuropathic pain development. We review the epigenetic writer, reader, and eraser proteins that participate in the transcriptional control of the expression of key ion channels and neurotransmitter receptors in the dorsal root ganglion after traumatic nerve injury, which is commonly used as a preclinical model of neuropathic pain. A better understanding of epigenetic reprogramming involved in the transition from acute to chronic pain could lead to the development of new treatments for neuropathic pain.

Clinical Hypnosis in Medical Care: A Mixed-Method Feasibility Study

Background

Preoperative hypnosis has shown promising effects in controlling side effects from breast cancer surgery, but the feasibility and effects are largely unknown outside the US.

Methods

A mixed-methods approach was applied involving a large-scale population survey and a small-scale pilot study. The survey assessed attitudes toward hypnosis in a representative sample from the general population (n = 1049), while the pilot study involved interviews with 5 women who received hypnosis prior to mastectomy/lumpectomy.

Results

In the survey, 8% reported to have previous experience with hypnosis, and 67% reported willingness to accept hypnosis in a medical setting. Increasing age was associated with more skepticism, while previous experience was associated with less skepticism. In the pilot study, 4 themes were identified: (1) caretaking, (2) experiences related to hypnosis, (3) thoughts and feelings related to diagnosis, and (4) surgery. All participants reported positive experiences related to hypnosis, and none described unpleasant side effects or postoperative pain (pain intensity > 3) after surgery.

Conclusions

The results indicate that the general public is positive toward clinical hypnosis as a supplement to medical treatment and that preoperative hypnosis is feasible in Norwegian breast cancer patients.

Trial Registration

ClinicalTrials.gov Identifier: NCT04300283.

Chronic postoperative pain: ubiquitous and scarcely appraised: narrative review

The International Association for the Study of Pain chose pain prevention as the theme for the 2020 Global Year. Chronic postoperative pain is one the many types of pain that can be potentially prevented. It develops or increases in severity after a surgery, persists for at least three months, even after ruling out all other possible causes of pain. To perform the present narrative review, the authors searched the PubMed database using the following keywords "postoperative pain" OR "postsurgical pain" AND "chronic" OR "persistent". The present review focused on the incidence, pain development and chronification, and predisposing factors. It also discusses prevention, diagnosis, and treatment of chronic postoperative pain. Awareness of occurrence of chronic postoperative pain and recognizing risk factors is crucial for the day-to-day practice of the anesthesiologist. Hence, numerous surgical patients can have their outcome improved by preventing chronic postoperative pain, a condition scarcely identified and without a well-established treatment.

Long-term analgesic and opioid prescription after surgery under general or neuraxial anesthesia: A retrospective nationwide sampling study

STUDY OBJECTIVE

Chronic postsurgical pain (CPSP) is a common and underreported but significant outcome following surgery. Pharmacological treatment with analgesics, including non-opioids and opioids, is frequently used. It has been debated whether neuraxial anesthesia can reduce persistent analgesic use. We aimed to survey long-term analgesic prescription after different surgeries under general and neuraxial anesthesia, using a nationwide database.

DESIGN

Retrospective case-control study.

SETTING

This study used data corresponding to the period from 2000 to 2016 from a longitudinal generation tracking database, which includes the claims data of 2 million randomly selected beneficiaries in Taiwan.

PATIENTS

Patients (n = 110,654) who underwent herniorrhaphy, hip/knee replacement, and lower-limb open reduction internal fixation (ORIF) or amputation were enrolled.

INTERVENTIONS

We categorized patients into general or neuraxial anesthesia groups, compared the rates of long-term analgesic prescription between the two groups, and estimated the adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs) using multivariable logistic regression analysis.

MAIN RESULTS

Lower rates of long-term analgesic prescription were noted in patients who underwent herniorrhaphy (3 months post-surgery: aOR, 0.88; 95% CI, 0.84-0.93; 6 months post-surgery: aOR, 0.90; 95% CI, 0.84-0.96), hip replacement (3 months post-surgery: aOR, 0.91; 95% CI, 0.85-0.97), and lower-limb ORIF (3 months post-surgery: aOR, 0.91; 95% CI, 0.88-0.94; 6 months post-surgery: aOR, 0.95; 95% CI, 0.92-0.99) under neuraxial anesthesia than under general anesthesia. Lesser long-term opioid prescription after herniorrhaphy (3 months post-surgery: aOR, 0.52; 95% CI, 0.36-0.75; 6 months post-surgery: aOR, 0.58; 95% CI, 0.42-0.81) and lower-limb ORIF (3 months post-surgery: aOR, 0.55; 95% CI, 0.47-0.65; 6 months post-surgery: aOR, 0.67; 95% CI, 0.56-0.80) was observed under neuraxial anesthesia than under general anesthesia.

CONCLUSIONS

Neuraxial anesthesia may be associated with lower rates of long-term analgesic and opioid prescription after some surgeries, especially herniorrhaphy and lower-limb ORIF.

Association of preoperative sleep pattern with posthysterectomy pain: a pilot study

STUDY OBJECTIVES

To evaluate the association of preoperative sleep pattern with posthysterectomy pain perception and satisfaction with surgery.

METHODS

This pilot study included women undergoing minimally invasive hysterectomy for benign conditions. Sleep quality, insomnia severity, and insomnia risk were assessed pre- and postoperatively via standard questionnaires. Total sleep time, wake after sleep onset, and sleep efficiency were measured before and after hysterectomy using daily sleep diaries and wrist-worn actigraphy. Pain perception and satisfaction with hysterectomy were assessed postoperatively. Repeated-measures analysis of variance, Pearson's correlation, and linear regression were used for analysis.

RESULTS

Twenty women participated; of them 16 had complete data and were analyzed. Total sleep time increased from 384 ± 102 minutes before to 468 ± 96 minutes after surgery (P = .023). Wake after sleep onset, a measure of sleep fragmentation, increased from 26 ± 15.1 minutes before to 52 ± 22.9 minutes after surgery (P = .014). Pearson's correlation showed preoperative total sleep time was inversely correlated with postoperative pain intensity (r = -.92, P = .01). Preoperative wake after sleep onset was positively correlated with postoperative pain intensity (r = .86, P = .008). Preoperative insomnia severity and insomnia risk were positively associated with postoperative pain and pain behaviors (β = 0.41, P < .05; β = 0.55, P < .01, respectively). Finally, preoperative sleep efficiency was positively associated with overall satisfaction with hysterectomy (β = 0.39, P < .05).

CONCLUSIONS

Sleep duration and fragmentation increase following hysterectomy. Shorter, more fragmented preoperative sleep is associated with greater postoperative pain intensity. Better preoperative sleep was associated with more satisfaction after hysterectomy. Further studies are needed to determine if preoperative sleep interventions such as cognitive behavioral therapy improve pain perception and satisfaction after hysterectomy.

Is Preoperative Quantitative Sensory Testing Related to Persistent Postsurgical Pain? A Systematic Literature Review

Persistent postsurgical pain (PPSP) is a common complication of surgery that significantly affects quality of life. A better understanding of which patients are likely to develop PPSP would help to identify when perioperative and postoperative pain management may require specific attention. Quantitative sensory testing (QST) of a patient's preoperative pain perception is associated with acute postoperative pain, and acute postoperative pain is a risk factor for PPSP. The direct association between preoperative QST and PPSP has not been reviewed to date. In this systematic review, we assessed the relationship of preoperative QST to PPSP. We searched databases with components related to (1) preoperative QST; (2) association testing; and (3) PPSP. Two authors reviewed all titles and abstracts for inclusion. Inclusion criteria were as follows: (1) QST performed before surgery; (2) PPSP assessed ≥3 months postoperatively; and (3) the association between QST measures and PPSP is investigated. The search retrieved 905 articles; 24 studies with 2732 subjects met inclusion criteria. Most studies (22/24) had moderate to high risk of bias in multiple quality domains. Fourteen (58%) studies reported a significant association between preoperative QST and PPSP. Preoperative temporal summation of pain (4 studies), conditioned pain modulation (3 studies), and pressure pain threshold (3 studies) showed the most frequent association with PPSP. The strength of the association between preoperative QST and PPSP varied from weak to strong. Preoperative QST is variably associated with PPSP. Measurements related to central processing of pain may be most consistently associated with PPSP.

The Persistence of Opioid Use Following Surgical Admission: An Australian Single-Site Retrospective Cohort Study

Background

Acute pain is common following surgery, with opioids frequently employed in its management. Studies indicate that commencing an opioid during a hospital admission increases the likelihood of long-term use. This study aimed to identify the prevalence of opioid persistence amongst opioid-naïve patients following surgery as well as the indication for use.

Methods

A retrospective review of patients who underwent a surgical procedure at the Royal Hobart Hospital, Tasmania, Australia, between August and September 2016 was undertaken. Patients were linked to the Tasmanian real-time prescription monitoring database to ascertain if they were subsequently dispensed a Schedule 8 opioid (morphine, codeine oxycodone, buprenorphine, hydromorphone, fentanyl, methadone, or tapentadol) and the indication for use.

Results

Of the 3275 hospital admissions, 1015 opioid-naïve patients were eligible for inclusion. Schedule 8 opioids were dispensed at or within 2 days of discharge in 41.7% of admissions. Thirty-nine (3.9%) patients received prescribed opioids 2-months post-discharge; 1.8% of the patients were approved by State Health to be prescribed Schedule 8 opioids regularly for a chronic condition at 6 months, and 1.3% received infrequent or one-off prescriptions for Schedule 8 opioids at 6 months. Thirteen (1.3%) patients continued Schedule 8 opioids for at least 6 months following their surgery, with the indication for treatment either related to the surgery or the condition which surgery was sought for.

Conclusion

This study found that there was a low rate of Schedule 8 opioid persistence following surgery, indicating post-surgical pain is not a significant driver for persistent opioid use.

Association of Early Postoperative Pain Trajectories With Longer-term Pain Outcome After Primary Total Knee Arthroplasty

IMPORTANCE

Studies to date have not comprehensively examined pain experience after total knee arthroplasty (TKA). Discrete patterns of pain in this period might be associated with pain outcomes at 6 to 12 months after TKA.

OBJECTIVES

To examine patterns of individual post-TKA pain trajectories and to assess their independent associations with longer-term pain outcome after TKA.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study combined data from a national US TKA cohort with ancillary pain severity data at 2 weeks and 8 weeks after the index TKA using a numeric rating scale. All participants received primary, unilateral TKA within the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) national network of community sites in 22 states or at the lead site (University of Massachusetts Medical School). Participants had a date of surgery between May 1, 2013, and December 1, 2014. The data analysis was performed between January 13, 2015, and July 5, 2016.

EXPOSURES

Pain trajectories in the postoperative period (8 weeks).

MAIN OUTCOMES AND MEASURES

Index knee pain at 6 months after TKA using the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain scale. Group-based trajectory methods examined the presence of pain trajectories in the postoperative period (8 weeks) and assessed whether trajectories were independently associated with longer-term pain (6 months).

RESULTS

The cohort included 659 patients who underwent primary TKA with complete data at 4 points (preoperative, 2 weeks, 8 weeks, and 26 weeks). Their mean (SD) age was 67.1 (8.0) years, 64.5% (425 of 659) were female, the mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) was 30.77 (5.66), 94.5% (613 of 649) were white, and the mean (SD) preoperative 36-Item Short Form Health Survey physical component summary and mental component summary scores were 34.1 (8.2) and 53.8 (11.4), respectively. Two pain trajectory subgroups were identified at 8 weeks after TKA: patients who experienced fast pain relief in the first 8 weeks after TKA (fast pain responders, composing 72.4% [477 of 659] of the sample) and patients who did not (slow pain responders, composing 27.6% [182 of 659] of the sample). After adjusting for patient factors, the pain trajectory at 8 weeks after TKA was independently associated with the mean KOOS pain score at 6 months, with a between-trajectory difference of -11.3 (95% CI, -13.9 to -8.7).

CONCLUSIONS AND RELEVANCE

The trajectory among slow pain responders at 8 weeks after surgery was independently associated with improved but greater persistent index knee pain at 6 months after TKA compared with that among fast pain responders. Early identification of patients with a trajectory of slow pain response at 8 weeks after TKA may offer an opportunity for interventions in the perioperative period to potentially improve the long-term pain outcomes after TKA.

Pregabalin Failed to Prevent Dry Eye Symptoms after Laser-Assisted in Situ Keratomileusis (LASIK) in a Randomized Pilot Study

PURPOSE

Perioperative pregabalin administration has been found to reduce the risk of persistent pain after a variety of surgical procedures. However, this approach has not been tested in relation to eye surgery. As such, the purpose of this study was to evaluate whether perioperative pregabalin can reduce the presence of dry eye (DE) symptoms, including eye pain, six months after laser-assisted in situ keratomileusis (LASIK).

METHODS

Prospective, masked, randomized single-center pilot study. Patients were treated with either pregabalin (oral solution of pregabalin 150 mg twice daily, first dose prior to surgery, continued for a total of 28 doses over 14 days) or placebo solution. The primary outcome was dry eye symptoms as measured by the Dry Eye Questionnaire 5 (DEQ-5). Secondary outcome measures included pain-related eye symptoms.

RESULTS

In total, 43 individuals were enrolled in the study and randomized to pregabalin (n = 21) or placebo (n = 22). Of those, 42 individuals completed the final visit after six months of follow-up. Some differences were noted between the two groups at baseline, including a higher frequency of females in the pregabalin group. At 6-months, there were no significant differences in the percentage of patients with DE symptoms (DEQ5 ≥ 6, 57% vs. 33%, p = 0.14), DE symptom severity (DEQ5, 6.6 ± 5.0 vs. 4.5 ± 4.2, p = 0.14), ocular pain intensity (numerical rating scale, 1.10 ± 1.48 vs. 0.38 ± 0.97, p = 0.08), or neuropathic pain complaints (Neuropathic Pain Symptom Inventory-Eye, 2.81 ± 4.07 vs. 3.14 ± 5.85, p = 0.83) between the pregabalin and control groups. Ocular signs were likewise similar between the groups, and of note, did not correlate with DE symptoms. The strongest predictor of DE symptoms six months post-surgery was the presence of DE symptoms prior to surgery.

CONCLUSIONS

Perioperative pregabalin did not reduce the frequency or severity of DE symptoms at a six month follow-up after LASIK in this small pilot study.

Identifying At-Risk Subgroups for Acute Postsurgical Pain: A Classification Tree Analysis

Objective

Acute postsurgical pain is common and has potentially negative long-term consequences for patients. In this study, we evaluated effects of presurgery sociodemographics, pain experiences, psychological influences, and surgery-related variables on acute postsurgical pain using logistic regression vs classification tree analysis (CTA).

Design

The study design was prospective.

Setting

This study was carried out at Chongqing No. 9 hospital, Chongqing, China.

Subjects

Patients (175 women, 84 men) completed a self-report battery 24 hours before surgery (T1) and pain intensity ratings 48-72 hours after surgery (T2).

Results

An initial logistic regression analysis identified pain self-efficacy as the only presurgery predictor of postoperative pain intensity. Subsequently, a classification tree analysis (CTA) indicated that lower vs higher acute postoperative pain intensity levels were predicted not only by pain self-efficacy but also by its interaction with disease onset, pain catastrophizing, and body mass index. CTA results were replicated within a revised logistic regression model.

Conclusions

Together, these findings underscored the potential utility of CTA as a means of identifying patient subgroups with higher and lower risk for severe acute postoperative pain based on interacting characteristics.

Local anesthetics and regional anesthesia versus conventional analgesia for preventing persistent postoperative pain in adults and children: A Cochrane systematic review and meta-analysis update

BACKGROUND

Regional anesthesia may mitigate the risk of persistent postoperative pain (PPP). This Cochrane review, published originally in 2012, was updated in 2017.

METHODS

We updated our search of Cochrane CENTRAL, PubMed, EMBASE and CINAHL to December 2017. Only RCTs investigating local anesthetics (by any route) or regional anesthesia versus any combination of systemic (opioid or non-opioid) analgesia in adults or children, reporting any pain outcomes beyond three months were included. Data were extracted independently by at least two authors, who also appraised methodological quality with Cochrane 'Risk of bias' assessment and pooled data in surgical subgroups. We pooled studies across different follow-up intervals. As summary statistic, we reported the odds ratio (OR) with 95% confidence intervals and calculated the number needed to benefit (NNTB). We considered classical, Bayesian alternatives to our evidence synthesis. We explored heterogeneity and methodological bias.

RESULTS

40 new and seven ongoing studies, identified in this update, brought the total included RCTs to 63. We were only able to synthesize data from 39 studies enrolling 3027 participants in a balanced design. Evidence synthesis favored regional anesthesia for thoracotomy (OR 0.52 [0.32 to 0.84], moderate-quality evidence), breast cancer surgery (OR 0.43 [0.28 to 0.68], low-quality evidence), and cesarean section (OR 0.46, [0.28 to 0.78], moderate-quality evidence). Evidence synthesis favored continuous infusion of local anesthetic after breast cancer surgery (OR 0.24 [0.08 to 0.69], moderate-quality evidence), but was inconclusive after iliac crest bone graft harvesting (OR 0.20, [0.04 to 1.09], low-quality evidence).

CONCLUSIONS

Regional anesthesia reduces the risk of PPP. Small study size, performance, null, and attrition bias considerably weakened our conclusions. We cannot extrapolate to other interventions or to children.

Targeted Genotyping Identifies Susceptibility Locus in Brain-derived Neurotrophic Factor Gene for Chronic Postsurgical Pain

BACKGROUND

The purpose of this study was to evaluate the association between single-nucleotide polymorphisms and chronic postsurgical pain.

METHODS

Using GoldenGate genotyping assays, we genotyped 638 polymorphisms within 54 pain-related genes in 1,152 surgical patients who were enrolled in our Persistent Pain after Surgery Study. Patients were contacted by phone to determine whether they had chronic postsurgical pain at 12 months. Polymorphisms identified were validated in a matched cohort of 103 patients with chronic postsurgical pain and 103 patients who were pain free. The functions of targeted polymorphisms were tested in an experimental plantar incisional nociception model using knock-in mice.

RESULTS

At 12 months after surgery, 246 (21.4%) patients reported chronic postsurgical pain. Forty-two polymorphisms were found to be associated with chronic postsurgical pain, 19 decreased the risk of pain, and 23 increased the risk of pain. Patients carrying allele A of rs6265 polymorphism in brain-derived neurotrophic factor (BDNF) had a lower risk of chronic postsurgical pain in the discovery and validation cohorts, with an adjusted odds ratio (95% CI) of 0.62 (0.43 to 0.90) and 0.57 (0.39 to 0.85), respectively. Age less than 65 yr, male sex, and prior history of pain syndrome were associated with an increased risk of pain. Genetic polymorphisms had higher population attributable risk (7.36 to 11.7%) compared with clinical risk factors (2.90 to 5.93%). Importantly, rs6265 is a substitution of valine by methionine at amino acid residue 66 (Val66Met) and was associated with less mechanical allodynia in BDNF mice compared with BDNF group after plantar incision.

CONCLUSIONS

This study demonstrated that genetic variant of BDNF rs6265G>A is associated with decreased risk of chronic postsurgical pain.

Perioperative pain management and chronic postsurgical pain after elective foot and ankle surgery: a scoping review

PURPOSE

Chronic postsurgical pain (CPSP) can occur after elective mid/hindfoot and ankle surgery. Effective treatment approaches to prevent the development of CPSP in this population have not been extensively investigated. The impact of multimodal strategies to prevent CPSP following elective mid/hindfoot surgery is unknown because of both the heterogeneity of acute pain management and the lack of a recognized definition particular to this surgery. This review aimed to identify and evaluate current pain management strategies after elective mid/hindfoot and ankle surgery.

SOURCES

Manual and electronic searches (MEDLINE, Embase, and Cochrane Library) were conducted of literature published between 1990 and July 2017. Comparative studies of adults undergoing elective mid/hindfoot and ankle surgery were included. Two reviewers independently reviewed studies and assessed their methodological quality.

PRINCIPAL FINDINGS

We found seven randomized-controlled trials meeting our inclusion criteria. Interventions focused on regional anesthesia techniques such as continuous popliteal sciatic and femoral nerve blockade. Participants were typically followed up to 48 hr postoperatively. Only one study assessed pain six months following elective mid/hindfoot and ankle surgery.

CONCLUSION

There is an overwhelming lack of evidence regarding CPSP and its management for patients undergoing elective mid/hindfoot and ankle surgery. The lack of a recognized and standard definition of CPSP after this group of surgeries precludes accurate and consistent evaluation.

Contributions of Nociresponsive Area 3a to Normal and Abnormal Somatosensory Perception

Traditionally, cytoarchitectonic area 3a of primary somatosensory cortex (SI) has been regarded as a proprioceptive relay to motor cortex. However, neuronal spike-train recordings and optical intrinsic signal imaging, obtained from nonhuman sensorimotor cortex, show that neuronal activity in some of the cortical columns in area 3a can be readily triggered by a C-nociceptor afferent drive. These findings indicate that area 3a is a critical link in cerebral cortical encoding of secondary/slow pain. Also, area 3a contributes to abnormal pain processing in the presence of activity-dependent reversal of gamma-aminobutyric acid A receptor-mediated inhibition. Accordingly, abnormal processing within area 3a may contribute mechanistically to generation of clinical pain conditions. PERSPECTIVE: Optical imaging and neurophysiological mapping of area 3a of SI has revealed substantial driving from unmyelinated cutaneous nociceptors, complementing input to areas 3b and 1 of SI from myelinated nociceptors and non-nociceptors. These and related findings force a reconsideration of mechanisms for SI processing of pain.

Cancer pain: where are we now?

Increasing numbers of those living with and beyond cancer presents a clinical challenge for pain specialists. A large proportion of these patients experience pain secondary to their disease or its treatment, impeding rehabilitation and significantly impacting upon their quality of life. The successful management of this pain presents a considerable challenge. This review aims to outline current concepts and treatment options, while considering nuances within pain assessment and the use of large-scale data to help guide further advances.

Epidemiology of Persistent Postsurgical Pain Manifesting as Dry Eye-Like Symptoms After Cataract Surgery

PURPOSE

To evaluate the epidemiology of persistent postsurgical pain (PPP) manifesting as dry eye (DE)-like symptoms 6 months after surgery.

METHODS

This single-center study included 119 individuals whose cataract surgeries were performed by a single surgeon at the Bascom Palmer Eye Institute and who agreed to participate in a phone survey 6 months after surgery. Patients were divided into 2 groups: the PPP group was defined as those with a Dry Eye Questionnaire-5 score ≥6 and without PPP as those with a Dry Eye Questionnaire-5 score <6 at 6 months after cataract surgery.

RESULTS

Mean age of the study population was 73 ± 8.0 years; 55% (n = 66) were female. PPP was present in 34% (n = 41) of individuals 6 months after surgery. Factors associated with an increased risk of PPP were female sex [odds ratio (OR) = 2.68, 95% confidence interval (CI) = 1.20-6.00, P = 0.01], autoimmune disorder (OR = 13.2, CI = 1.53-114, P = 0.007), nonocular chronic pain disorder (OR = 4.29, CI = 1.01-18.1, P = 0.06), antihistamine use (OR = 6.22, CI = 2.17-17.8, P = 0.0003), antireflux medication use (OR = 2.42, CI = 1.04-5.66, P = 0.04), antidepressant use (OR = 3.17, CI = 1.31-7.68, P = 0.01), anxiolytic use (OR = 3.38, CI = 1.11-10.3, P = 0.03), and antiinsomnia medication use (OR = 5.28, CI = 0.98-28.5, P = 0.047). PPP patients also reported more frequent use of artificial tears (P < 0.0001), higher ocular pain levels (P < 0.0001), and greater neuropathic ocular pain symptoms, including burning (P = 0.001), wind sensitivity (P = 0.001), and light sensitivity (P < 0.0001).

CONCLUSIONS

PPP in the form of persistent DE-like symptoms is present in approximately 34% of individuals 6 months after cataract surgery. The frequency of PPP after cataract surgery is comparable to that of other surgeries including laser refractive surgery, dental implants, and genitourinary procedures.

Quality of recovery after surgery for cancer treatment

INTRODUCTION

Assessment of quality of recovery is important as an end-point for outcome research. This study aims to determine the incidence and determinants of poor quality of recovery (PQR) after surgery in patients scheduled for curative neoplastic surgery.

MATERIALS AND METHODS

An observational prospective study was performed in consecutive patients undergoing surgery for cancer treatment. The Quality of Recovery 15 score (QoR-15) was applied on the day before surgery (T0) and 24h after (T1). PQR was defined for patients with a QoR-15 score lower than the mean QoR-15 score at T1 minus one standard deviation. Preoperative quality of life was assessed with EuroQol-5D. Frailty and disability were defined using Clinical Frailty Scale and World Health Organization Disability Assessment Schedule 2.0.

RESULTS

One hundred and thirty-eight patients were enrolled and 31 (15.9%) were identified as having PQR. At T0, patients with PQR presented lower scores on total QoR-15 (P=.03) and had more problems on EuroQol-5D in mobility (P=.014), self-care (P=.027) and usual activities domains (P=.019). The difference of QoR-15 score between T1 and T0 was higher in PQR patients (P<.001). PQR had more frequently Revised Cardiac Risk Index (RCRI)≥2 (P=.012) and were more frequently frail (P=.03). PQR patients stayed longer in the hospital (P=.034).

CONCLUSION

PQR patients had lower QoR-15 before surgery, poor quality of life, were more frequently frail and had high cardiac risk factors. PQR patients stayed longer in the hospital.

Post Mastectomy Pain is No Longer Nightmare

Background PMPS nowadays is common due to advances in both; diagnosis and treatment of cancer breast. Choosing proper treatments can improve the patients’ quality of life. Cancer breast is common and quite important disease and female in our family must be aware of it. Improvement of the diagnosis and treatment PMPS lead to increased patient’s satisfaction and decrease fear of cancer breast. Objective Discuss different methods for management of PMPS with less side effects, adequate analgesia, improvement of quality of life, and better patient satisfaction in the future. Methods Treatment approaches include both pharmacological interventions and non-pharmacological strategies. However, current treatments of the PMPS are near-optimal and prevention much better than treatment. Conclusion Continuous perioperative thoracic epidural Fentanyl–bupivacaine infusion was much better in pain relief, less sedating effect and shorter duration of hospital and ICU stay than continuous perioperative entanyl intravenous infusion in patients undergoing major upper gastrointestinal cancer surgery.

[The role of brain n-3 fatty acids-GPR40/FFAR1 signaling in pain]

G-protein-coupled receptor 40 (GPR40)/free fatty acid receptor (FFAR) 1 is activated by long-chain fatty acids such as docosahexaenoic acid (DHA). Its receptor is expressed predominantly in the central nervous system (CNS) and in β-cells in the pancreatic Islets. We have already demonstrated that the intracerebroventricular administration of DHA or GW9508, a GPR40/FFAR1 agonist, suppresses formalin-induced pain behavior. It also attenuates complete Freund's adjuvant-induced mechanical allodynia and thermal hyperalgesia, suggesting that these effects occur by increasing β-endorphin release from propiomelanocortin neurons. Furthermore, we found that the brain GPR40/FFAR1 signaling may involve in the regulation of the descending pain control system, whereas the deletion of GPR40/FFAR1 might exacerbate mechanical allodynia in postoperative pain. Therefore, it is possible that the brain n-3 fatty acid-GPR40/FFAR1 signaling may play a key role in the modulation of the endogenous pain control system and emotional function. Here, we discuss the role of brain n-3 fatty acids-GPR40/FFAR1 signaling in a pain, and we review the current status and future prospects of the brain GPR40/FFAR1.

Factors Leading to Persistent Postsurgical Pain in Adolescents Undergoing Spinal Fusion: An Integrative Literature Review

PROBLEM

Adolescent idiopathic scoliosis (AIS) is the most common spinal deformity among children and adolescents and the most frequent reason for corrective spinal fusion (SF). Of the children and adolescents who undergo SF, a significant number will experience persistent postoperative pain (PPP). This integrative literature review was conducted to identify and synthesize perioperative factors that may contribute to risk of developing PPP.

ELIGIBILITY CRITERIA

Articles which addressed PPP within the last 10years and primary research on postoperative pain outcomes in adolescents after SF were selected for review.

SAMPLE

15 articles which met eligibility criteria were included.

RESULTS

Preoperative pain intensity was the most significant factor identified in the development of PPP and increased postoperative pain. Social function and psychological factors also have role in the development of PPP. There were no theoretical models or frameworks for evaluating PPP incidence in adolescent with AIS after SF.

CONCLUSIONS

Perioperative factors such as, preoperative pain, correction magnitude, pain coping, anxiety and social functioning are vital to understanding a child's risk of PPP following SF. There is a need for theoretically-based studies to assess PPP among children and adolescents with AIS after SF surgery.

IMPLICATIONS

The Biobehavioral Pain Network (BPN) model was proposed, to encompass biological, social and psychological domains which may be responsible for incidence of PPP in children undergoing SF. Such a model can be used to systematically develop and evaluate personalized postoperative pain management strategies for this patient population.

Persistent Postoperative Pain: Pathophysiology, Risk Factors, and Prevention

OBJECTIVE

Persistent postoperative pain (PPOP) is the second most common reason for a patient to seek care at a chronic pain center. Many of the patients seen with prolapse or incontinence are at risk for developing PPOP as a result of the surgeries done for these problems. The pathophysiology of this disabling pain disorder is well understood, and the risk factors are easy to identify. Once identified, perioperative interventions can be offered to attempt to prevent PPOP.

METHODS AND RESULTS

Evaluation of articles obtained using a MEDLINE search involving chronic pain and PPOP, including prevalence, pathophysiology, and prevention was reviewed. The concept of central censitization and the key role it plays in chronic pain disorders were also reviewed. A history of chronic pain (anywhere) as well as findings of levator myalgia, allodynia, and hypertonic pelvic floor disorders is critical in identifying patients at risk for PPOP.

CONCLUSIONS

Identification of patients at risk allows the clinician to educate the patient about the risk of PPOP and the various perioperative interventions that can be used to prevent its development. Further studies will be required to determine how effective these interventions are in patients undergoing surgery for incontinence and/or pelvic organ prolapse.

Chronic post-amputation pain: peri-operative management - Review

Study design

Narrative review.

Method

Eight bibliographic databases were searched for studies published in the (last five years up until Feb 2017). For the two database searches (Cochrane and DARE), the time frame was unlimited. The review involved keyword searches of the term 'Amputation' AND 'chronic pain'. Studies selected were interrogated for any association between peri-operative factors and the occurrence of chronic post amputation pain (CPAP).

Results

Heterogeneity of study populations and outcome measures prevented a systematic review and hence a narrative synthesis of results was undertaken. The presence of variation in two gene alleles (GCH1 and KCNS1) may be relevant for development of CPAP. There was little evidence to draw conclusions on the association between age, gender and CPAP. Pre-operative anxiety and depression influenced pain intensity post operatively and long-term post amputation pain (CPAP). The presence of pre-amputation pain is correlated to the development of acute and chronic post amputation pain while evidence for the association of post-operative pain with CPAP is modest. Regional anaesthesia and peri-neural catheters improve acute postoperative pain relief but evidence on their efficacy to prevent CPAP is limited. A suggested whole system pathway based on current evidence to optimize peri-operative amputation pain is described.

Conclusion

The current evidence suggests that optimized peri-operative analgesia reduces the incidence of acute peri-operative pain but no firm conclusion can be drawn on reducing risk for CPAP.

Prediction of persistent post-operative pain: Pain-specific psychological variables compared with acute post-operative pain and general psychological variables

BACKGROUND

Psychological variables and acute post-operative pain are of proven relevance for the prediction of persistent post-operative pain. We aimed at investigating whether pain-specific psychological variables like pain catastrophizing add to the predictive power of acute pain and more general psychological variables like depression.

METHODS

In all, 104 young male patients undergoing thoracic surgery for pectus excavatum correction were studied on the pre-operative day (T0) and 1 week (T1) and 3 months (T2) after surgery. They provided self-report ratings (pain-related: Pain Catastrophizing Scale, Pain Anxiety Symptoms Scale = PASS, Pain Vigilance and Awareness Questionnaire = PVAQ; general psychological: Screening for Somatoform Symptoms, State-Anxiety Inventory-X1, Center for Epidemiologic Studies Depression Scale = CES-D). Additional predictors (T1) as well as criterion variables (T2) were pain intensity (Numerical Rating Scale) and pain disability (Pain Disability Index).

RESULTS

Three months after surgery, 25% of the patients still reported clinically relevant pain (pain intensity ≥3) and over 50% still reported pain-related disability. Acute post-operative pain as well as general psychological variables did not allow for a significant prediction of persistent post-operative pain; in contrast, pain-related psychological variables did. The best single predictors were PASS for pain intensity and PVAQ for pain disability.

CONCLUSIONS

Pain-related psychological variables derived from the fear-avoidance model contributed significantly to the prediction of persistent post-operative pain. The best possible compilation of these measures requires further research. More general psychological variables may become relevant predictors later in the medical history.

SIGNIFICANCE

Our results suggest that pain-specific psychological variables such as pain anxiety and pain hypervigilance add significantly to the prediction of persistent post-operative pain and might even outperform established predictors such as acute pain and general psychological variables. Clinicians might benefit from the development of time-economic screening tools based on these variables.

The role of intraoperative interventions to minimise chronic postsurgical pain

Chronic postsurgical pain (CPSP) is the most common complication following surgery, with increasing evidence of both its prevalence and severity. While awareness of the various risk factors for this long-term condition is also increasing, effective prevention remains elusive. In this review, we describe the increasing evidence for preventive or 'protective' strategies. Controversies and conflicting human data are presented along with suggestions for improved future study.

AMPAkines Target the Nucleus Accumbens to Relieve Postoperative Pain

BACKGROUND

AMPAkines augment the function of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in the brain to increase excitatory outputs. These drugs are known to relieve persistent pain. However, their role in acute pain is unknown. Furthermore, a specific molecular and anatomic target for these novel analgesics remains elusive.

METHODS

The authors studied the analgesic role of an AMPAkine, CX546, in a rat paw incision (PI) model of acute postoperative pain. The authors measured the effect of AMPAkines on sensory and depressive symptoms of pain using mechanical hypersensitivity and forced swim tests. The authors asked whether AMPA receptors in the nucleus accumbens (NAc), a key node in the brain's reward and pain circuitry, can be a target for AMPAkine analgesia.

RESULTS

Systemic administration of CX546 (n = 13), compared with control (n = 13), reduced mechanical hypersensitivity (50% withdrawal threshold of 6.05 ± 1.30 g [mean ± SEM] vs. 0.62 ± 0.13 g), and it reduced depressive features of pain by decreasing immobility on the forced swim test in PI-treated rats (89.0 ± 15.5 vs. 156.7 ± 18.5 s). Meanwhile, CX546 delivered locally into the NAc provided pain-relieving effects in both PI (50% withdrawal threshold of 6.81 ± 1.91 vs. 0.50 ± 0.03 g; control, n = 6; CX546, n = 8) and persistent postoperative pain (spared nerve injury) models (50% withdrawal threshold of 3.85 ± 1.23 vs. 0.45 ± 0.00 g; control, n = 7; CX546, n = 11). Blocking AMPA receptors in the NAc with 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione inhibited these pain-relieving effects (50% withdrawal threshold of 7.18 ± 1.52 vs. 1.59 ± 0.66 g; n = 8 for PI groups; 10.70 ± 3.45 vs. 1.39 ± 0.88 g; n = 4 for spared nerve injury groups).

CONCLUSIONS

AMPAkines relieve postoperative pain by acting through AMPA receptors in the NAc.