Chronic pain after surgery: pathophysiology, risk factors and prevention

Preoperative quantitative sensory testing and robot-assisted laparoscopic hysterectomy for endometrial cancer: can chronic postoperative pain be predicted?

Objectives Chronic postoperative pain is prevalent after robot-assisted laparoscopic hysterectomy for endometrial cancer. Preoperative Quantitative Sensory Testing (QST) has been utilized to identify patients at risk of developing chronic postoperative pain after a range of surgical procedures. The aim of this prospective, observational study was to (1) determine the prevalence of chronic postoperative pain, (2) assess selected preoperative risk factors for chronic postoperative pain, and (3) evaluate if preoperative QST profiling could predict the development of chronic postoperative pain following robot-assisted laparoscopic hysterectomy for endometrial cancer. Methods One-hundred and sixty consecutive patients were included and handheld pressure algometry, cuff pressure algometry, temporal summation of pain, conditioned pain modulation, and heat pain thresholds were assessed prior to surgery. Patients were asked to fill out a questionnaire concerning pain in the pre- and post-operative time period six months after surgery. Chronic postoperative pain was defined as persistent, moderate to severe pain (mean visual analogue scale (VAS)≥3) on a daily basis six months after surgery. Results The prevalence of chronic postoperative pain after robot-assisted laparoscopic hysterectomy for endometrial cancer was of 13.6% (95% CI 8.4-20.4%). Patients that would develop chronic postoperative pain had a lower BMI (p=0.032), a higher prevalence of preoperative pelvic pain (p<0.001), preoperative heat pain hyperalgesia (p=0.043) and a higher level of acute postoperative pain (p<0.001) when compared to patients that would not develop chronic postoperative pain. A logistic regression model demonstrated that the presence of preoperative pelvic pain was a significant, independent predictive risk factor for development of chronic postoperative pain (OR=6.62, 95% CI 2.26-19.44), whereas none of the QST parameters could predict postoperative pain. Conclusions Preoperative QST assessment could not predict the development of chronic postoperative pain despite preoperative heat pain hyperalgesia in patients that would develop chronic postoperative pain.

Erector spinae plane block for postoperative pain and recovery in hepatectomy: A randomized controlled trial

BACKGROUND

The randomized controlled study aimed to examine the efficacy of preoperative ultrasound-guided erector spinae plane (ESP) block combined with ropivacaine in patients undergoing hepatectomy.

METHODS

A total of 60 patients were randomized to ESP block group receiving ropivacaine (Group A) and control group (Group B), n = 30 per group. Visual analog scale (VAS) was recorded in both the groups during rest and movement at the various time intervals. Both the groups were also compared for time to initial anal exhaust, analgesic usage, early postoperative complications and side-effects, walk distance after the operation, time to out-of-bed activity, and duration of hospital stay.

RESULTS

No significant differences were observed in the demographic characteristics. For group A, when compared to group B, VAS scores during rest and movement within post-operative 24 hours were decreased, the time of first anus exhaust and ambulation were earlier, analgesic consumption and the incidence of postoperative nausea, vomiting and headache was reduced, the duration of hospital stay were shorter with longer walk distance.

CONCLUSION

ESP block combined with ropivacaine treatment effectively reduced early postoperative pain and improved recovery after hepatectomy.

The influence of the choice of preemptive analgesia on long-term postsurgical pain after tibial plateau leveling osteotomy in dogs

OBJECTIVE

To evaluate the prevalence of chronic postsurgical pain (CPSP) after tibial plateau leveling osteotomy (TPLO) in dogs and to determine the influence of preemptive locoregional analgesia on CPSP.

STUDY DESIGN

Retrospective study.

ANIMALS

One hundred twenty client-owned dogs.

METHODS

Medical records of dogs that underwent TPLO between 2012 and 2016 were reviewed for demographic information and type of preemptive analgesia. Owners were contacted to retrospectively assess the quality of life of their dogs by using the Helsinki Chronic Pain Index (HCPI) before and 6 months after surgery and at the time of questioning. An HCPI score > 12 was considered indicative of CPSP. Medical records were reviewed for demographic information and type of preemptive analgesia. A cumulative logit model was used to assess correlation of type of perioperative analgesia, HCPI, and demographic data.

RESULTS

The HCPI score was consistent with CPSP in 41 of 101 dogs with long-term follow-up (2.9 ± 1.5 years after surgery). Chronic postsurgical pain was documented in 11 of 32 and 13 of 28 dogs that received a spinal or epidural injection, respectively, or in 28 of 80 and 25 of 67 dogs with sciatic-femoral block at 6 months or with long-term follow-up after TPLO, respectively (P > .05). A negative correlation was found between HCPI and both weight and age 6 months after surgery. Only weight remained negatively correlated 2.9 years after surgery.

CONCLUSION

Forty-one percent of dogs that were evaluated exhibited HCPI values compatible with CPSP long-term after TPLO, regardless of the type of preemptive analgesia. Increased body weight was a negative prognostic factor for CPSP development.

CLINICAL SIGNIFICANCE

Additional studies are required to evaluate CPSP development after TPLO.

The American Society of Anesthesiologists Physical Status (ASA-PS) Risk Group Classification Can Be Used to Anticipate Functional Recovery Outcomes after the Surgical Treatment of Female Urinary Incontinence with Transobturator Suburethral Tape

INTRODUCTION

Stress urinary incontinence (SUI) has an incidence of 15-80% in women. One of the most widely used surgical techniques for treatment is the placement of a suburethral transobturator tape (TOT). Although this technique has a relatively low morbidity rate, it is not exempt from intraoperative or postoperative complications, which can have an impact on functional recovery, understood as the return to routine life prior to the intervention.

AIMS

To assess the time for functional recovery in women operated on for SUI by TOT; to identify complications and related factors, according to anaesthetic risk, which condition the time to functional recovery; and proposals for improvements in the prevention of possible complications and in reducing functional recovery time.

MATERIALS AND METHODS

A non-concurrent prospective observational multicenter study of 891 women undergoing TOT for stress urinary incontinence since 1 April 2003, who were successful in achieving urinary continence (completely dry). Study groups: GA (n = 443): patients with ASA I risk. GB (n = 306): patients with ASA II risk. GC (n = 142): patients with anaesthetic risk ASA III. Investigated variables: age, body mass index, follow-up time, secondary diagnoses, surgical history, obstetric-gynecological history, toxic habits, and complications derived from surgery: bleeding, pain, infection. Descriptive statistics, Student's t test, Chi2, Fisher, ANOVA, multivariate analysis, significance for p < 0.05.

RESULTS

Mean age was 60.10 years (SD13.38), with no difference between groups. Mean body mass index (BMI) was 26.55 kg/m² (SD 4.51), lowest in GA. GB had more HT (38.6%) than GC (23.23%), more type 2 diabetes (19.83% versus 10.56%), and more respiratory disorders (6.97% versus 2.11%). There were more women with anxiety in GB (19.3%) than in GC (6.33%) (p = 0.0221) and GA (10.51%) (p = 0.0004). There was more hypothyroidism in GB (16.08%) compared to GC (2.11%) and GA (9.07%). There was more history of curettage in GC (11.97%) versus GB (5.63%); and more pelvic surgery in GB (71.31%) and GC (66.9%) compared to GA (32.57%). There were more concomitant treatments with benzodiazepines in GC (27.46%) and GB (28.41%) than in GA (8.86%), and more parapharmacy treatments in GB (17.96%) than in GC (6.33%). Following the operation, 113 patients had some sign or symptom that required medical attention: in GA 48 (10.83%), in GB 49 (16.06%), in GC 16 (13.22%). Mean days until functional recovery in patients with complications: in GA 5.72 (SD2.05); bleeding 3 (SD1), pain 6.40 (SD1.34), and infection 7.33 (SD0.57), with fewer days for bleeding than for pain or infection. GB: 27.96 (SD 28.42), bleeding 3 (SD0), pain 46.69 (SD31.36), infection 10.83 (SD3.90); lowest for patients with bleeding. GC: 9.44 (SD 2.50); for bleeding 7.66 (SD2. 08), pain 10.66 (SD1.15), infection 10 (SD3.46); no differences. Overall, for women with bleeding, the time was 4.16 days (SD1.94); less in GA and GB than in GC. Pain, at 31.33 days (SD 30.70), was the factor that most delayed functional recovery; in GB women, it took longer to return to work due to pain (45.96, SD31.36) compared to GA (6.4, SD 1.34) and GC (10.66, SD1.15). In women with infection, overall mean time was 10.11 days (SD 3.61) with no difference between groups.

CONCLUSIONS

Mean time for the return to normal activity in patients who underwent TOT for SUI is 5 days if there are no complications, and 16.91 days if there are any. The ASA-SP risk group classification can be used to anticipate functional outcomes. An ASA-PS risk-based functional recovery forecasting protocol should be adapted, especially ASA II patients who may present with long-term disabling postoperative pain. Preventive management measures are proposed that favour functional recovery.

Efficacy of Precise Foot Massage Therapy on Pain and Anxiety Following Cardiac Surgery: Pilot Study

BACKGROUND

Pain is the most pervasive distressing symptom following cardiac surgery. Forty percent of postoperative cardiac patients report inadequate pain management. Undertreated acute pain results in increased anxiety, delayed wound healing, and increased chance of persistent chronic pain. Foot massage is a safe, visible complementary approach to manage acute pain following surgery.

AIM

The aim of this study is to evaluate the efficacy of integrating foot massage therapy for managing postcardiac pain.

METHOD

A randomized placebo controlled single blinded trial comparing foot massage to placebo was conducted at a large hospital in Saudi Arabia. Thirty-one patients who had undergone cardiac surgery (16 in experimental and 15 in placebo group) participated in the study. Ten-minute foot massage was delivered to the experimental group by a nurse researcher, twice during one day, within 30 minutes after receiving an opioid pain medication.

RESULTS

The findings of this study indicate that foot massage significantly (p < .05) decreases pain intensity and anxiety in patients who have undergone cardiac surgery compared with a placebo control group.

CONCLUSION

Providing non-pharmacologic interventions for pain is the responsibility of the nursing staff. Foot massage is within the scope of nursing practice and is a safe and effective manner of improving patient care. Foot massage in conjunction with pharmacological interventions is effective in improving pain and anxiety. Future studies should consider focusing on frequency, dose, feasibility, acceptability, and participants' satisfaction.

Role of Spinal Cord Akt-mTOR Signaling Pathways in Postoperative Hyperalgesia Induced by Plantar Incision in Mice

Poor postoperative pain (POP) control increases perioperative morbidity, prolongs hospitalization days, and causes chronic pain. However, the specific mechanism(s) underlying POP is unclear and the identification of optimal perioperative treatment remains elusive. Akt and mammalian target of rapamycin (mTOR) are expressed in the spinal cord, dorsal root ganglion, and sensory axons. In this study, we explored the role of Akt and mTOR in pain-related behaviors induced by plantar incision in mice. Plantar incision activated spinal Akt and mTOR in a dose-dependent manner. Pre-treatment with Akt inhibitors intrathecally prevented the activation of mTOR dose-dependently. In addition, blocking the Akt-mTOR signaling cascade attenuated pain-related behaviors and spinal Fos protein expression induced by plantar incision. Our observations demonstrate that Akt-mTOR might be a potential therapeutic target for the treatment of POP.

Persistent pain in intensive care survivors: a systematic review

BACKGROUND

According to earlier studies where the main aim has been quality of life, there is growing evidence of increased levels of persistent pain in survivors of critical illness. The cause of admission and several factors during intensive care may have associated risk factors for pain persistence. This systematic review aims to determine the incidence or prevalence of persistent pain after critical illness and to identify risk factors for it.

METHODS

Six databases were searched, and eventually nine studies were included in the final systematic process. The validity of observational and cross-sectional studies was analysed using the National Institute of Health 'Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies'.

RESULTS

The incidence of persistent pain after intensive care varied from 28% to 77%. Risk factors for persistent pain were acute pain at discharge from ICU, higher thoracic trauma score, surgery, pre-existing pain, organ failure, longer length of ventilator or hospital stay, and sepsis. No difference in incidence between medical and surgical patients was found.

CONCLUSIONS

New systematic, observational studies are warranted to identify persistent pain-related factors in intensive care to improve pain management protocols and thereby diminish the risk of persistent pain after ICU stay.

Chronic Pain Following Cosmetic Breast Surgery: A Comprehensive Review

INTRODUCTION

Cosmetic breast surgery is commonly performed in the United States; 520,000 procedures of the total 1.8 million cosmetic surgical procedures performed in 2018 were breast related. Postoperative chronic pain, defined as lasting 3 or more months, has been reported in a wide variety of breast surgical procedures including breast augmentation, reduction mammaplasty, mastectomy, and mastectomy with reconstruction. Patient characteristics associated with the development of postoperative chronic pain following cosmetic breast surgery include a younger age, larger BMI, smaller height, postoperative hyperesthesia, and elevated baseline depression, anxiety, and catastrophizing scores. The anatomical distribution of chronic pain following breast augmentation procedures is dependent upon incision site placement; pectoral and intercostal nerves have been implicated. The purpose of this review is to provide an update on the current literature addressing the pathophysiology, clinical presentation, and treatment of patients presenting with chronic postoperative pain following cosmetic breast surgery.

METHODS

A comprehensive literature review was performed in MEDLINE, PubMed, and Cochrane databases from 1996 to 2019 using the terms "cosmetic surgery", "breast surgery", "postoperative pain", and "chronic pain".

RESULTS

Cosmetic breast surgery can have a similar presentation as post-mastectomy pain syndrome and thus have overlapping diagnostic criteria. Seven domains are identified for a diagnosis of PBSPS: Pain after breast surgery, neuropathic in nature, at least a moderate intensity of pain, as defined as within the middle one-third of the selected pain scale, pain for at least 6 months, symptoms occurring for 12 or more hours a day for a minimum of 4 days each week, pain in at least one of the following sites: breast, chest wall, axilla, or arm on the affected side, pain exacerbated by movement. Patient risk factors and surgical risk factors may influence the development of chronic post-cosmetic surgery breast pain. Improved perioperative analgesia including preoperative regional nerve anesthesia and postoperative catheter infusion have been shown to improve chronic postoperative pain outcomes.

CONCLUSIONS

The present review provides a discussion of clinical presentation, pathophysiology, and treatment and preventative strategies for chronic breast pain following cosmetic surgery. This review provides evidence from multiple randomized controlled trials (RCTs) and systematic reviews of efficacy and effectiveness. While chronic postoperative breast pain remains challenging to treat, various preventative strategies have been described to improve postoperative pain outcomes.

Perioperative Analgesic Effects of Preemptive Ultrasound-Guided Rectus Sheath Block Combined with Butorphanol or Sufentanil for Single-Incision Laparoscopic Cholecystectomy: A Prospective, Randomized, Clinical Trial

Purpose

Pain after single-incision laparoscopic cholecystectomy (SILC), especially visceral pain, often troubles patients and doctors. Whether preemptive butorphanol can relieve visceral pain in patients undergoing SILC remains unknown. The goal of this study was to assess the efficacy of ultrasound-guided bilateral rectus sheath block (RSB) and butorphanol for perioperative analgesia in patients undergoing SILC.

Patients and Methods

Fifty-eight patients who met the criteria were randomly divided into two groups, both of which were given preemptive RSB. Patients were given either butorphanol 0.02mg/kg (group B, n=29) or sufentanil 0.1 µg/kg (group S, n=29) as preemptive analgesia. The primary outcome was the cumulative frequency of rescue analgesic request within 24 hours after operation. Secondary outcomes were numeric rating scale (NRS) scores (from 0 to 10) of incisional pain and visceral pain, the length of hospital stay and the incidence of postoperative adverse events.

Results

The frequency of postoperative rescue analgesic request of group S was significantly higher than that of group B (P=0.021). The NRS scores for visceral pain were lower in group B at 2, 6 and 12 hours after surgery than in group S (both P<0.001). The occurrence of postoperative nausea and vomiting (PONV) was significantly higher in group S. There were no significant differences between two groups for other outcomes.

Conclusion

Butorphanol can provide sufficient visceral pain treatment after SILC than the dose of sufentanil in equal analgesic effect.

[Factors Related to Persistent Postoperative Pain after Cardiac Surgery: A Systematic Review and Meta-Analysis]

PURPOSE

This study aimed at identifying factors related to persistent postoperative pain after cardiac surgery and estimating their effect sizes.

METHODS

The literature search and selection was conducted in four different databases (CINAHL, Cochrane Library, PubMed, and PQDT) using the Preferred Reporting Items for Systematic Review and Meta-Analysis Statement. A total of 14 studies met the inclusion criteria and were systematically reviewed. For the meta-analysis, R was used to analyze 30 effect sizes of for both individual and operative factors as well as publication biases from a total of nine studies.

RESULTS

The meta-analysis revealed that persistent postoperative pain after cardiac surgery was related to one individual factor (gender) and two operative factors (acute postoperative pain and use of the internal mammary artery). Operative factors (OR=5.26) had a larger effect size than individual factors (OR=1.53).

CONCLUSION

Female gender, acute pain after surgery, and use of the internal mammary artery are related factors to persistent postoperative pain. The development of interventions focusing on modifiable related factors, such as acute postoperative pain, may help to minimize or prevent PPP after cardiac surgery.

Paracetamol as a basic component of a modern approach to adequate perioperative analgesia

The problem of adequate perioperative anesthesia is one of the most pressing in the current health care system, given its medical, humanistic and socio-economic aspects. Currently, the standard of postoperative analgesia is multimodal analgesia (MMA). One of the major and required components of MMA is paracetamol, which has antipyretic and analgesic effects with limited peripheral anti-inflammatory activity. Most authors consider intravenous paracetamol as a base drug in a multimodal analgesia strategy for a variety of surgical interventions, which reduces the need for opioids and reduces the side effects of the latter, which in turn significantly affects the results of treatment and the length of hospital stay.Numerous studies in many countries have created a broad evidence base for the clinical use of this drug. Due to its pharmacokinetic and pharmacodynamic properties, it has been shown that intravenous paracetamol has several advantages over oral and rectal forms: early and more effective onset of analgesia and stable maintenance of the therapeutic dose of paracetamol are explained by the formation of a faster and higher peak in the concentration of the drug. The side effects of using paracetamol can be compared with placebo. The mechanism of action of the drug is different from the mechanism of action of NSAIDs, however, is still not fully understood. It may possibly involve inhibition of cyclooxygenase, cannabinoid, or nitric oxide pathways in the central nervous system. Intravenous paracetamol is a safe and effective first-line drug for the treatment of moderate pain in the perioperative period.

Correction to: Chronic Postoperative Pain After Robot-Assisted Laparoscopic Hysterectomy for Endometrial Cancer by Lunde S, Petersen KK, Kugathasan P, Arendt-Nielsen L and Søgaard-Andersen E. Journal of Gynecologic Surgery 2019;35(3);140-146. DOI: 10.1089/gyn.2018.0068

[This corrects the article DOI: 10.1089/gyn.2018.0068.].

Magnetic resonance spectroscopy across chronic pain disorders: a systematic review protocol synthesising anatomical and metabolite findings in chronic pain patients

BACKGROUND

Chronic pain is pain greater than 3 months duration that may result from disease, trauma, surgery, or unknown origin. The overlap between the psychological, behavioural, and management aspects of pain suggest that limbic brain neurochemistry plays a role in chronic pain pathology. Proton magnetic resonance spectroscopy (1H-MRS) can evaluate in vivo brain metabolites including creatine, N-acetylaspartate, myo-inositol, choline, glutamate, glutamine, and gamma-aminobutyric acid in chronic pain; however, a comprehensive systemic review of metabolite expression patterns across all brain areas has yet to be performed.

METHODS AND ANALYSIS

Online databases including PubMed/MEDLINE, Google Scholar, EMBASE, the Cochrane Library, OVID, and PsycINFO will be searched for articles relating to 1H-MRS and chronic pain. Study inclusion criteria will include ages of between 18 and 65 years with a definite diagnosis of chronic pain, no comorbidities, clearly stated brain volumes of interest, and imaging protocols, with comparisons to healthy controls. Two reviewers will extract data relating to volumes of interest, metabolites, study participant demographics, diagnostic method and pain scores, treatments and duration of treatment, scanner information, 1H-MRS acquisition protocols, and spectral processing software. Where possible, volumes of interest will be reassigned as regions of interest consistent with known regional anatomical and functional properties to increase the power and relevance of the analysis. Statistical analyses will then be conducted using STATA. A central common pathway may exist for chronic pain due to the behavioural manifestations and management similarities between its different types. The goal of this systemic review is to generate a comprehensive neurochemical theory of chronic pain in different brain compartments.

SYSTEMATIC REVIEW REGISTRATION

This study is registered with PROSPERO CRD42018112640.

Inpatient Pain Scores and Narcotic Utilization Based on American Society of Anesthesiologists Score Following Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective.

OBJECTIVE

To examine the relationship between American Society of Anesthesiologists (ASA) score and inpatient pain and narcotics consumption following anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

Higher ASA scores have been previously linked to increased postoperative complication rates, healthcare costs, length of stay, and hospital readmissions. However, to our knowledge, there have not been previous investigations into the association between ASA scores and postoperative inpatient pain and narcotics utilization following ACDF.

METHODS

Patients who underwent a single-level, primary ACDF were retrospectively reviewed and stratified into two cohorts based on ASA score less than or equal to 2 or ASA score more than 2. ASA score was tested for association with demographic variables and perioperative characteristics using student's t test, chi-squared analysis, and Fisher exact test. Inpatient pain scores and narcotics consumption on each postoperative day were then compared between cohorts using bivariate linear regression.

RESULTS

Two hundred eleven patients who underwent ACDF were included: 184 had an ASA score less than or equal to 2 and 27 had an ASA score more than 2. Higher ASA score was associated with older age, higher comorbidity burden as measured by the modified Charlson Comorbidity Index (CCI), and lower prevalence of obesity. Higher ASA scores were associated with longer duration of hospital stay, while other perioperative characteristics were similar between ASA score cohorts. There were no differences in inpatient Visual Analog Scale (VAS) pain scores, or hourly, daily, and cumulative inpatient narcotic consumption between cohorts on any postoperative day.

CONCLUSION

This retrospective investigation demonstrated that a higher ASA score is associated with increased operative time following ACDF. However, ASA score was determined not to be an independent risk factor that can predict postoperative pain or narcotics consumption among patients who undergo ACDF. Therefore, postoperative pain in the inpatient setting can be managed with similar modalities regardless of ASA score for patients undergoing ACDF.

LEVEL OF EVIDENCE

3.

Chronic pain following laparoscopic living-donor nephrectomy: Prevalence and impact on quality of life

Chronic postsurgical pain (CPSP) following laparoscopic donor nephrectomy (LDN) is a disregarded topic. In this cross-sectional study, all consecutive patients who underwent an LDN at the Radboud University Medical Center (Radboudumc; 2003-2016) were approached for participation. Five hundred twelve living kidney donors were included and asked to complete two questionnaires, including the McGill Pain Questionnaire and the RAND Short Form-36 Health Status Inventory (RAND SF-36) regarding their health-related quality of life (HRQoL). The mean prevalence of CPSP following LDN was 5.7%, with a mean follow-up time of 6 years. Possible predictors of CPSP following LDN are severe early postoperative pain, previous abdominal surgery, and preexisting backache. The RAND SF-36 revealed an impaired HRQoL in patients with CPSP when compared to patients without CPSP. In conclusion, this study revealed that the prevalence of CPSP following LDN is substantial. Given the possible association between the presence of CPSP and impaired HRQoL scores, living kidney donors should be well informed in the preoperative phase about the risk of CPSP.

[Research progress of the role of postoperative pain in the development of postoperative cognitive dysfunction in geriatric patients]

Previous studies have shown that postoperative cognitive dysfunction (POCD) is related to multiple factors including age, postoperative trauma, inflammation, postoperative pain, and anesthesia, among which postoperative pain is thought to play an important role in the development of POCD. This review summarizes the recent findings in the study of the role of postoperative pain in the pathogenesis of POCD in light of nerve injuries, neural remodeling and stress, and the progress in the prevention and treatment of POCD in elderly patients. It is of vital important to assess the postoperative pain and formulate adequate analgesic regimens for effective prevention and management of POCD to protect the brain functions of elderly patients.

Efficacy of the Parasympathetic Tone Activity monitor to assess nociception in healthy dogs anaesthetized with propofol and sevoflurane

OBJECTIVE

To compare a Parasympathetic Tone Activity (PTA) monitor with cardiovascular changes in invasive mean arterial pressure (IMAP) and heart rate (HR) when evaluating the response to nociceptive stimuli in anaesthetized dogs.

STUDY DESIGN

Prospective experimental study.

ANIMALS

A group of nine (seven male and two female) adult Beagle dogs weighing 13.4 ± 1.5 kg (mean ± standard deviation).

METHODS

Anaesthesia was induced with propofol and maintained with sevoflurane in oxygen. Electrical stimuli of different nociceptive intensities were applied for 30 seconds. Stimuli were classified in each patient according to the response obtained (relevant change ≥ 20%) as low (no response), medium (PTA only) or high (PTA and IMAP/HR). Immediate and averaged values of PTA, IMAP and HR were recorded every second from 60 seconds before to 120 seconds after application of the nociceptive stimulus. Time to nociceptive response and peak response were evaluated with analysis of variance and t test.

RESULTS

Immediate PTA baseline values did not differ significantly before application of the low, medium and high stimuli (73 ± 15, p = 0.966). Immediate PTA response was observed with the medium stimulus at 33 ± 7 seconds with a maximum decrease of 57 ± 13% at 69 ± 5 seconds. With the high stimulus, the immediate PTA response was of a similar magnitude to the medium stimulus with a response at 28 ± 7 seconds (p = 0.221) and a maximum decrease of 68 ± 15% (p = 0.115) at 72 ± 7 seconds (p = 0.436). The cardiovascular change occurred (22 ± 8 seconds) prior to the immediate PTA response (p = 0.032).

CONCLUSIONS AND CLINICAL RELEVANCE

The PTA monitor detected nociceptive stimuli at lower intensities than those eliciting cardiovascular changes. However, nociceptive stimuli of higher intensities provoked cardiovascular changes that occurred before a PTA response was observed.

Postoperative pain following Descemet membrane endothelial keratoplasty (DMEK): a prospective study

PURPOSE

To evaluate postoperative pain following Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Seventy-one patients completed perioperatively (day before surgery, day of surgery, 1st, 2nd, and 3rd day after surgery) four different questionnaires (a hospital internal protocol, QUIPS, PainDETECT®, and SF36) regarding their pain and other clinical parameters such as constipation, tiredness, vertigo, sleep disorders, concentration disorders, nausea, and emesis. All standardised questionnaires were evaluated to quantify average pain intensity as well as maximum pain intensity (NRS, 0 [no pain] to 10 [maximal pain], respectively). Analgesic treatment and intraocular pressure (IOP) during the perioperative stay were documented.

RESULTS

Mean average pain intensity was 0.70 ± 1.64 before surgery, 1.97 ± 2.05 on the day of surgery, 1.39 ± 1.68 on day 1, 0.87 ± 1.36 on day 2, and 0.81 ± 1.24 on day 3 after surgery. Maximum pain intensity was 0.65 ± 1.81 before surgery, 3.35 ± 2.98 on the day of surgery, 2.68 ± 2.99 on day 1, 1.49 ± 2.15 on day 2, and 1.26 ± 2.02 on day 3 after surgery. During the first three postoperative days, over 90% of the patients stated no or well tolerable pain. Eighty-three percent had postoperatively no need for analgesics at all. On the first two postoperative days, maximum IOP correlated significantly with reported increased maximum pain intensity (p = 0.043 and p = 0.029, respectively). All patients had very little problems with constipation, tiredness, vertigo, sleep disorder, concentration disorders, nausea, and emesis.

CONCLUSIONS

DMEK is associated with low postoperative pain intensity. Strong pain increase may indicate IOP elevation and should be further investigated and treated.

CLINICAL TRIAL REGISTRATION

German Clinical Trial Register (DRKS00013995).

Persistent pain after cesarean delivery

The incidence of persistent pain after cesarean deliveries (CD) varies but is much lower than after comparable surgeries. However, with over four million deliveries annually and a rising CD rate, even a low prevalence of persistent pain after CD impacts many otherwise healthy young women. Consideration of the pathophysiology of persistent pain after surgery and the risk factors predisposing women to persistent and chronic pain after CD provides insights into the prevention and treatment of persistent pain; and improves the quality of care and recovery after CD. The findings that the peripartum state and oxytocin confer protection against persistent pain may provide new and interesting perspectives for the prevention and treatment of chronic pain caused by trauma or surgery. Predictive tools available to identify and target patients at high risk of acute and chronic pain have mostly weak to modest predictive correlations and many are either not clinically feasible or too time-consuming to apply. Persistent pain has been linked to the severity of acute postoperative pain and opioid exposure. Modified surgical techniques, neuraxial anesthesia and opioid-sparing analgesia may help limit the development of persistent and chronic pain. The goal of this narrative review is to examine the incidence of persistent pain after CD; review briefly the underlying pathophysiology of persistent pain and the transition from acute to chronic pain (with particular emphasis on the uniqueness after CD); and to review modifiable risk factors and prevention strategies that identify at-risk patients and allow tailored treatment.

Efficacy of magnetic resonance imaging with an SPGR sequence for the early evaluation of knee cartilage degeneration and the relationship between cartilage and other tissues

Rationale and objectives

The aim of this study was to investigate the efficacy of magnetic resonance imaging (MRI) with a spoiled gradient-recalled (SPGR) sequence to evaluate early knee cartilage degeneration and the relationship between cartilage and other tissues using a modified Whole-Organ Magnetic Resonance Imaging Score (WORMS).

Materials and methods

Eighty-four patients with knee joint pain were evaluated by X-ray and MRI with an SPGR sequence from June 2015 to December 2016. Joint degeneration was graded by two experienced radiologists using the Kellgren-Lawrence (K-L) grading scale. The modified WORMS was used to evaluate cartilage lesions, bone marrow abnormalities, bone cysts, osteophytes, joint effusion and synovitis. The difference between the WORMS of the SPGR and the T2 sequences evaluated by the Wilcoxon signed-rank test was determined, and the relationships between the WORMS features were evaluated by a Spearman correlation.

Results

The modified WORMS for the cartilage lesion evaluation was significantly higher with the SPGR sequence than with the T2 sequence (P < 0.05). The cartilage lesions showed a moderate correlation with osteophytes, synovitis and joint effusion (Rs > 0.40, P < 0.05) and weak correlations with bone marrow abnormalities and bone cysts (Rs < 0.4, P < 0.05).

Conclusion

The modified WORMS evaluation using MRI with the SPGR sequence was much better than the normal sequence for early knee osteoarthritis (OA). The cartilage lesions are associated with bone marrow abnormalities and the other features of OA.

Sex differences in negative affect and postoperative pain in patients undergoing total knee arthroplasty

Background

Knee osteoarthritis (OA) is among the most common and disabling persistent pain conditions, with increasing prevalence in the developed world, and affects women to a greater degree than men. In the USA, the growth of knee OA has been paralleled by an increase in rates of total knee arthroplasty (TKA), a surgical treatment option for late-stage knee OA. While TKA outcomes are generally good, postoperative trajectories of pain vary widely, with some patients reporting a complete absence of pain, but with a significant minority reporting worsening pain. Biopsychosocial factors, including anxiety and depression, are known to contribute importantly to the experience of joint pain, with women reporting a higher degree of negative affective symptoms.

Methods

This study investigated sex differences in TKA outcomes in age-matched groups of men and women at two academic medical centers. Pain and physical function were assessed in 100 patients (50 men and 50 women) during the perioperative period (preoperative visit—6 weeks postsurgical). The association of preoperative negative affect (anxiety and depression scores) to postoperative pain and function was evaluated, with specific attention to sex differences in this relationship.

Results

Overall, women reported more baseline pain-related physical dysfunction (although not higher baseline pain scores), as well as higher acute postoperative pain scores during the 2 weeks following TKA than their male counterparts. By 6 weeks postoperatively, sex differences in reported pain were no longer evident. Interestingly, although women reported higher preoperative levels of emotional distress than men, preoperative anxiety and depression scores were better predictors of severe postoperative pain among men than women, throughout the postoperative test period.

Conclusions

This study underlines the importance of considering sex and psychosocial factors, as well as their interaction, in understanding postsurgical pain trajectories.

Lead extraction for reduction of chronic pain related to cardiovascular implantable electronic device

AIMS

Chronic pain at the cardiovascular implantable electronic device (CIED) generator or lead insertion site that is not otherwise manageable carries a IIA indication for extraction. However, limited data exist evaluating causes of pain and outcomes of extraction in eliminating pain. A multi-centre retrospective observational study was conducted to evaluate outcomes of patients undergoing device extraction for treatment of chronic device pain.

METHODS AND RESULTS

Twenty-seven out of 2188 lead extraction candidates (1.3%) met the chronic pain IIA indication for extraction [50 ± 16 years; 14 (51%) women]. Onset, severity, triggers, and pain management were measured before and after extraction. Device type, procedure done (with/without reimplantation), and positive tissue cultures were noted. Pain was reported as constant (n = 14; 50%), intermittent (n = 13; 46%), and movement-triggered (n = 14; 50%). Average severity of pain was seven out of 10 (10 being the worst). Post-extraction, 18 (66%) received freedom from pain, including all patients with poorly formed pockets (n = 2) and subclinical infections (n = 2). Of the 18, 11 underwent reimplantation (61%) without recurrent pain. Nine still had pain (44 ± 17 years; seven women) after extraction. Eight of the nine underwent reimplantation, three on the contralateral chest wall and five ipsilaterally. Pain severity decreased (n = 5), increased (n = 1), or was unchanged (n = 3).

CONCLUSION

Chronic pain at the CIED generator site can present as chronic or movement-triggered pain, and can be due to subclinical infection or a poorly formed device pocket. Extraction relieved constant and intermittent pain in two-thirds of patients. Extraction appears less successful in eliminating pain in women who undergo subsequent reimplantation.

Update and future perspective of behavioral medicine in the treatment for chronic pain

Chronic pain is a biopsychosocial condition, and behavioral medicine has made significant contributions to the understanding of the phenomenon and optimization of therapeutic outcomes. The objective of this article is to provide future perspectives of behavioral medicine in pain management based upon recent development in the field. We will briefly review the mainstream approach of cognitive-behavioral therapy, its variations and new and innovative approaches that are on the horizon. We also review strategies that address potential barriers to pain management. Behavioral medicine is a promising field in pain medicine. The future growth is likely to come from addressing how we incorporate the patient heterogeneity into our treatment approaches and a better understanding of its role in a multimodal treatment.

A review of dexketoprofen trometamol in acute pain

OBJECTIVE

Dexketoprofen trometamol is a modified non-selective COX inhibitor with a rapid onset of action that is available as both oral and parenteral formulations. The aim of this narrative review was to assess the efficacy and tolerability/safety of dexketoprofen trometamol in acute pain states using the best available published scientific evidence (randomized controlled clinical trials and systematic reviews/meta-analyses).

METHODS

Literature retrieval was performed via Medline, Embase and the Cochrane Library (from inception up to March 2017) using combinations of the terms "randomized controlled trials", "dexketoprofen", "celecoxib", "etoricoxib", "parecoxib" and "acute pain".

RESULTS

Single-dose dexketoprofen trometamol provides effective analgesia in the treatment of acute pain, such as postoperative pain (dental and non-dental surgery), renal colic, acute musculoskeletal disorders and dysmenorrhea, and reduces opioid consumption in the postoperative setting. It has a rapid onset of action (within 30 minutes) and is well tolerated during short-term treatment. Direct comparisons with COX-2 inhibitors are lacking; however, the efficacy and tolerability of single-dose dexketoprofen trometamol appears to be consistent with that seen with celecoxib, etoricoxib and parecoxib in the acute pain setting.

CONCLUSION

In conclusion, dexketoprofen trometamol appears to provide similar analgesic efficacy to COX-2 inhibitors when used to treat acute pain, has a rapid onset of action, is well tolerated, and has an opioid-sparing effect when used as part of a multimodal regimen in the acute pain setting.

The Effect of Preoperative Medications on Length of Stay, Inpatient Pain, and Narcotics Consumption After Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

This is a retrospective cohort study.

OBJECTIVE

To determine the association between preoperative medications and length of stay, inpatient pain, and narcotics consumption after a minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND DATA

Previous studies have identified risk factors for increased length of hospital stay, inpatient pain, and narcotics consumption. However, little is known regarding the effects of preoperative medications on outcomes after spine surgery.

METHODS

A prospectively maintained surgical database of patients undergoing primary, single-level MIS TLIF was retrospectively reviewed. Preoperative medications taken within 30 days before surgery were recorded for each patient and categorized by medication type. Poisson regression with robust error variance was used to determine the association between preoperative medications and length of stay, pain scores, and narcotics consumption. Multivariate analysis was performed using a backwards, stepwise regression to identify independent risk factors.

RESULTS

In total, 138 patients were included in this analysis. On bivariate analysis, benzodiazepines were associated with longer hospital stays [relative risk (RR)=2.03; P=0.031]. Benzodiazepines (RR=3.71; P<0.001) and preoperative narcotics (RR=2.60; P=0.012) were risk factors for pain ≥7 on postoperative day 0. On multivariate analysis, benzodiazepines were an independent risk factor for prolonged stay. Benzodiazepines, narcotics, and nonsteroidal anti-inflammatories were identified as independent risk factors for increased postoperative pain.

CONCLUSIONS

These results suggest that benzodiazepines are a risk factor for increased length of stay and postoperative pain after MIS TLIF. Preoperative narcotics and nonsteroidal anti-inflammatories were also identified as risk factors for postoperative pain though this did not lead to increases in narcotics consumption. Patients taking these medications should undergo more vigilant perioperative monitoring for adequate pain management. More work must be done to further elucidate the association between preoperative medications and postoperative outcomes after MIS TLIF.

Psychometric evaluation of the Danish version of a modified Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R-D) for patients hospitalized with acute abdominal pain

Background and aims This paper forms part of a study evaluating the effect of patient-controlled oral analgesia for patients admitted to hospital with acute abdominal pain. Pain is a subjective experience, and a multifaceted evaluation tool concerning patient-reported outcome measures is needed to monitor, evaluate, and guide health care professionals in the quality of pain management. The Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R) is a validated multifaceted evaluation tool for measuring patient-reported pain experiences to evaluate different pain management interventions. The aim of this study was to evaluate the psychometric properties of a modified Danish version of the Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R-D) used during and after hospitalization for patients with acute abdominal pain. Methods The APS-POQ-R was translated into Danish and two slightly different questionnaires were formed. Questionnaire one had 39 items and the six subscales pain severity (pain), perception of care (satisfaction), pain interference with function (activity) and emotions (emotion), side effects of treatment (safety), and patient-related barriers to pain management. The questionnaire focused on time during hospital stay and was to be completed at discharge. Questionnaire two included 25 items and the five subscales pain, satisfaction, activity, emotion, and safety and focused on time at home and was to be completed daily 1 week after discharge. The questionnaires were tested on 156 patients with acute abdominal pain. Internal consistency reliability and construct validity was examined. Results In both questionnaires, the results of correlations and tests for internal consistency reliability showed a Cronbach's alpha of >0.7 for the pain, activity, and emotion subscales, but the value was ≥0.69 for the satisfaction subscale. In questionnaire one, Cronbach's alpha was ≤0.64 for the safety subscale, but this was 0.73 when the item "itching" was deleted. In questionnaire two, Cronbach's alpha was ≤0.51 for the safety subscale. For the patient-barrier subscale in questionnaire one, Cronbach's alpha was ≤0.62 for any combination of the items in the subscale. The results of the construct validity and factor analysis showed a five-factor structure in questionnaire one and a three-factor structure in questionnaire two. In questionnaire one, items from the pain, activity, emotion, and safety subscales, except for the items "least pain" and "itching," loaded on factor one. In questionnaire two, all items from the pain, activity, and emotion subscales loaded on factor one. Conclusions The modified APS-POQ-R-D demonstrated adequate psychometric properties for the five subscales pain severity (pain), perception of care (satisfaction), pain interference with function (activity) and emotions (emotion), side effects of treatment (safety), but not for the patient-barrier subscale for patients hospitalized with acute abdominal pain. Consequently, the APS-POQ-R-D may be used without the patient-barrier subscale. Implications The clinical implications of this study may help clinicians with investigating how acute patients manage pain during and after hospital admission.

Laws limiting the prescribing or dispensing of opioids for acute pain in the United States: A national systematic legal review

BACKGROUND

Opioid overdose is a continuing public health crisis. In response to an increasing recognition of the negative outcomes sometimes associated with the use of opioid analgesics, states have taken a number of steps attempting to reduce inappropriate prescribing of these medications. These include the imposition of strict legal limitations on the amount or duration that opioid analgesics may be prescribed or dispensed to patients with acute pain.

METHODS

We conducted a systematic, multi-source legal review of state laws that impose mandatory limits on the ability of medical professionals to prescribe or dispense opioids for the treatment of acute pain. We also systematically searched for and examined publicly available documents on state legislative and regulatory bodies' websites. All relevant laws were downloaded and systematically coded.

RESULTS

By the end of 2017, twenty-six states had passed laws that impose mandatory limits on the prescribing or dispensing of opioids for acute pain. The oldest of these laws became effective as early as 1989, but most are much newer: approximately 65% (17/26) were passed in 2017. There is wide variation in the characteristics of these laws.

CONCLUSION

Just over half of all states have enacted laws that restrict the prescribing or dispensing of opioids for acute pain. To date, there is no data on whether and to what extent these laws mediate opioid-related morbidity and mortality, as well as whether they are associated with negative unintended outcomes. Research into these questions is urgently needed.

AAPT Diagnostic Criteria for Peripheral Neuropathic Pain: Focal and Segmental Disorders

Peripheral neuropathic pain is among the most prevalent types of neuropathic pain. No comprehensive peripheral neuropathic pain classification system that incorporates contemporary clinical, diagnostic, biological, and psychological information exists. To address this need, this article covers the taxonomy for 4 focal or segmental peripheral neuropathic pain disorders, as part of the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership and the American Pain Society (APS) collaborative to develop a standardized, evidence-based taxonomy initiative: the ACTTION-APS Pain Taxonomy (AAPT). The disorders-postherpetic neuralgia, persistent posttraumatic neuropathic pain, complex regional pain disorder, and trigeminal neuralgia-were selected because of their clinical and clinical research relevance. The multidimensional features of the taxonomy are suitable for clinical trials and can also facilitate hypothesis-driven case-control and cohort epidemiologic studies. PERSPECTIVE: The AAPT peripheral neuropathic pain taxonomy subdivides the peripheral neuropathic pain disorders into those that are generalized and symmetric and those that are focal or segmental and asymmetric. In this article, we cover the focal and segmental disorders: postherpetic neuralgia, persistent posttraumatic neuropathic pain, complex regional pain disorder, and trigeminal neuralgia. The taxonomy is evidence-based and multidimensional, with the following dimensions: 1) core diagnostic criteria; 2) common features; 3) common medical and psychiatric comorbidities; 4) neurobiological, psychosocial, and functional consequences; and 5) putative neurobiological and psychosocial mechanisms, risk factors, and protective factors.

Pelvic Pain and Apical Prolapse Surgery: A Population-Based Retrospective Cohort Study

OBJECTIVES

The aims of this study were to evaluate the association of preoperative pelvic pain with operative characteristics and the association of patient and operative characteristics with postoperative pain.

METHODS

This is a retrospective cohort study utilizing Clinformatics DataMart, a large national commercial insurance database. We collected data for patients older than 18 years who underwent apical prolapse surgery between January 2005 and December 2014. We stratified data by preoperative (prior) pain and analyzed for associations of prior and postoperative pain. Logistic regression analysis was performed using SAS software.

RESULTS

A total of 14,440 patients met inclusion criteria and were analyzed. Patients with prior pain were more likely to have an abdominal (open or laparoscopic) approach, a concomitant hysterectomy, but less likely to have additional repairs or a mesh insertion (P < 0.001). Postoperative pain was less with a concomitant hysterectomy, whether they had prior pain (odds ratio [OR], 0.56; 95% confidence interval [CI], 0.41-0.77) or not (OR, 0.68; 95% CI, 0.56-0.82). Additional vaginal repairs were associated with more postoperative pain for those without prior pain (OR, 1.63; 95% CI, 1.3-2.04). Age older than 45 years was associated with less pain. Length of hospital stay of more than 2 days was associated with more pain.

CONCLUSIONS

Patients with prior pain were more likely to undergo an abdominal approach and have a concomitant hysterectomy. Postoperative pain was less with a concomitant hysterectomy, but more with additional vaginal repairs. There is a need to include pain as an outcome in future studies, particularly clinical trials.

Pain, impaired functioning, poor satisfaction and diminished health status eight years following perilunate (fracture) dislocations

Purpose: Perilunate (fracture) dislocations are rare injuries and diminished functional outcomes are reported. However, Patient Reported Outcomes (PROs) following these injuries are rarely described. The aim of this study was to investigate the long-term impact of perilunate (fracture) dislocations using a range of measures, including pain, function, and quality of life.Materials and Methods: This cross-sectional study was conducted from January 2016 until March 2016. Eleven patients who had suffered from perilunate (fracture) dislocations between August 1996 and January 2014 were matched on age and gender with 22 healthy controls. Functional outcome included range of motion and grip strength measurements. The Patient Reported Outcomes included: Patient Reported Wrist Evaluation, Disability of Arm, Shoulder and Hand questionnaire, Michigan Hand Questionnaire and the Short Form-36.Results: The 11 patients that were included (9 males) had a median age at injury of 38 years (IQR 33; 54) and median follow up of 97 months (IQR 84-193). Flexion/extension (mean difference -60°, 95% CI -76, -43, p < 0.001) and ulnar/radial deviation (mean difference -28°, 95% CI -38, -18, p < 0.001) were significantly diminished in patients following perilunate (fracture) dislocations. Grip strength was not affected. The patients experienced significantly more pain as assessed on all pain subscales. Physical functioning was significantly worse in the group with perilunate (fracture) dislocations as assessed on all function subscales, except the PRWE function score and the subscale physical functioning of the Short Form-36. Satisfaction as measured with the Michigan Hand Questionnaire satisfaction subscale (mean difference -36, 95% CI -57, -16, p = 0.002) was also reported poorer. No difference was found regarding work participation.Conclusions: A perilunate (fracture) dislocation has a significant impact on everyday life, as patients experience diminished range of motion, pain, diminished physical functioning, diminished satisfaction and report lower general health status than healthy controls. However, no consequences for work participation were found in this study. Level of evidence 3.Implications for rehabilitationFlexion/extension and ulnar/radial deviation remains limited following perilunate (fracture) dislocations.Grip strength is not diminished in patients with perilunate (fracture) dislocations.Pain, restrictions in physical functioning, diminished satisfaction and lower general health status are likely to be present following perilunate (fracture) dislocations.If conservative treatment including pain medication and rehabilitation strategies do not relief pain following perilunate (fracture) dislocations, surgical treatment options such as wrist denervation or arthrodesis should be considered.

Post-operative pain in mice is prolonged by diet-induced obesity and rescued by dietary intervention

The prevalence of obesity has increased at an alarming rate during past decades. Obesity is associated with pathophysiological disorders that can evolve and increase the risk of heart disease, diabetes and hypertension. While the impact of diabetes on post-operative recovery is now known, the consequences of obesity on post-operative pain remain much less explored. Here, we show that obesity affects post-operative pain resolution and leads to a chronic pain state in mice. Several mechanisms were identified as implicated in the prolonged post-operative pain. Indeed, we found that following a hind paw incision, high fat diet prolonged glial cell activation in the spinal cord. It also altered the expression of neurotrophins and increased inflammatory and endoplasmic reticulum stress markers in both central and peripheral nervous systems. Moreover, we show that a dietary intervention, leading to weight reduction and decreased inflammation, was able to restore normal pain sensitivity in mice suffering from chronic pain for more than 10 weeks. In conclusion, our data demonstrate that obesity is responsible for pain chronicization. This is clearly of importance in a clinical post-operative setting.

Classification of acute pain trajectory after breast cancer surgery identifies patients at risk for persistent pain: a prospective observational study

Purpose

Predictive value and accuracy of the acute pain trajectory were compared with those of pain intensity at 1 day after the surgery for pain prevalence at 6 months after the surgery.

Materials and methods

Female patients scheduled for breast cancer surgery were eligible for this study. Patients were questioned about pain intensity daily during the 7 days after surgery. Presence of pain, its location, and intensity as well as the Japanese version of the quality of the recovery-40 (QOR-40) were determined in an interview prior to and at 6 months after the surgery. Acute pain trajectory was determined by a group-based trajectory modeling analysis that was based on the pain intensity at 1–7 days after surgery. Predictive value of the acute pain trajectory for the presence of pain at 6 months after the surgery was assessed by a logistic regression model. The predictive value was compared with pain intensity at 1 day after the surgery.

Results

A total of 123 participants completed the 6-month follow-up. The three-cluster model (mild, moderate, and severe pain) was considered to be the most statistically appropriate model for the acute pain trajectory. After 6 months, 51.2% and 8.9% of participants reported pain and severe pain, respectively. Presence of pain at 6 months after the surgery was associated with poor recovery. The severe pain cluster was significantly associated with the presence of pain at 6 months after the surgery (adjusted odds ratio, 9.40; P<0.001 vs mild pain cluster).

Conclusion

Classification of patients according to the acute pain trajectory, when compared with the classification according to pain intensity at 1 day after the surgery, made it possible to predict with better precision those patients who will develop persistent postsurgical pain.

Targeting toll-like receptor-4 (TLR4)-an emerging therapeutic target for persistent pain states

Toll-like receptors (TLRs) are a family of pattern recognition receptors that initiate signaling in innate and adaptive immune pathways. The highly conserved family of transmembrane proteins comprises an extracellular domain that recognizes exogenous and endogenous danger molecules and an ectodomain that activates downstream pathways in response. Recent studies suggest that continuous activation or dysregulation of TLR signaling may contribute to chronic disease states. The receptor is located not only on inflammatory cells (meningeal and peripheral macrophages) but on neuraxial glia (microglia and astrocytes), Schwann cells, fibroblasts, dorsal root ganglia, and dorsal horn neurons. Procedures blocking TLR functionality have shown pronounced effects on pain behavior otherwise observed in models of chronic inflammation and nerve injury. This review addresses the role of TLR4 as an emerging therapeutic target for the evolution of persistent pain and its role in noncanonical signaling, mediating anomalous pro-algesic actions of opiates. Accordingly, molecules targeting inhibition of this receptor have promise as disease-modifying and opioid-sparing alternatives for persistent pain states.

Persistent inflammatory pain alters sexually-motivated behavior in male rats

Urine from pro-œstrus female rodents evokes increased levels of sexually-motivated behaviors in males, including sniffing and scent marking of the urine spot as well as activation of brain reward regions. Stressors such as social defeat can adversely impact urine scent marking behavior in male rodents, an effect that can be mitigated with anti-depressant drugs. Persistent pain is also known to be a potent stressor, producing elevated levels of plasma corticosterone as well as reduced sucrose preference and reduced social interaction. However, the effect of persistent pain on sexually-motivated behavior is unknown. Here, we compared urine scent marking behavior in male rats for up to 3 weeks following intra-articular injection of Complete Freund’s Adjuvant (CFA) or sham injection. CFA-injected rats exhibited profound and ongoing deficits in static weight bearing capacity. CFA-induced persistent inflammatory pain increased plasma corticosterone levels and reduced urine scent marking behavior in male rats. Moreover, while the vast majority of injured rats showed decreased urine scent marking preference for the pro-œstrus female urine spot, male rats with higher baseline scent marking preference also exhibited higher post-injury scent marking preference, more sniffing behavior and lower levels of plasma corticosterone, compared to those with lower baseline scent marking preference. Overall, scent marking behavior may be an ethologically relevant behavioral predictor of persistent pain-induced stress in rats, representing a novel translational approach to understanding chronic pain comorbidities.

Clinical Outcome, Social Impact and Patient Expectation: a Purposive Sampling Pilot Evaluation of Patients in Benin Seven Years After Surgery

BACKGROUND

Access to affordable and timely surgery is not equitable around the world. Five billion people lack access, and while non-governmental organizations (NGOs) help to meet this need, long-term surgical outcomes, social impact or patient experience is rarely reported.

METHOD

In 2016, Mercy Ships, a surgical NGO, undertook an evaluation of patients who had received surgery seven years earlier with Mercy Ships in 2009 in Benin. Using purposive sampling, patients who had received maxillofacial, plastics or orthopedic surgery were invited to attend a surgical evaluation day. In this pilot study, we used semi-structured interviews and questionnaire responses to assess patient expectation, surgical and social outcome.

RESULTS

Our results show that seven years after surgery 35% of patients report surgery-related pain and 18% had sought further care for a clinical complication of their condition. However, 73% of patients report gaining social benefit from surgery, and overall patient satisfaction was 89%, despite 35% of patients saying that they were unclear what to expect after surgery indicating a mismatch of doctor/patient expectations and failure of the consent process.

CONCLUSION

In conclusion, our pilot study shows that NGO surgery in Benin provided positive social impact associated with complication rates comparable to high-income countries when assessed seven years later. Key areas for further study in LMICs are: evaluation and treatment of chronic pain, consent and access to further care.

Postoperative local incision analgesia for acute pain treatment in patients with hepatocellular carcinoma

OBJECTIVE

The present study aimed to investigate the analgesic effect and safety of using local incision analgesia to treat acute postoperative pain in patients with hepatocellular carcinoma (HCC).

METHOD

A cohort of 60 patients undergoing liver cancer resection was randomly divided into three groups (n=20 per group): local incision analgesia (LIA) group, which received local infiltration with ropivacaine combined with a postoperative analgesia pump; intravenous patient-controlled analgesia (PCA) group, which received fentanyl intravenous analgesia postoperatively; and the control group, which received tramadol hydrochloride injection postoperatively according to the NRS scoring system. The postoperative analgesic effect in each group was compared and tumor recurrence (survival) was analyzed using the Kaplan-Meier method.

RESULTS

NRS scores, rate of analgesic usage, ambulation time (h) and intestinal function recovery time (h) were significantly reduced in LIA group compared with the control group at each postoperative time point (6, 12, 24 and 48 hours; p<0.05). Additionally, the NRS scores of LIA patients at 12 hours post-surgery was significantly reduced compared with PCA group (p<0.05), and the occurrence of postoperative adverse events in LIA group was significantly lower than that in PCA group (p<0.05). Survival analysis demonstrated that the mean survival time (tumor recurrence) was significantly increased in LIA group compared with the control group (χ2=4.749; p=0.029).

CONCLUSION

Local incision analgesia improves the analgesic effect, causes fewer adverse reactions and increases postoperative survival time. Our study demonstrated that local incision analgesia is a safe and effective method of postoperative pain management following hepatectomy.

Improved Outcomes Associated With the Use of Intravenous Acetaminophen for Management of Acute Post-Surgical Pain in Cesarean Sections and Hysterectomies

Background

Post-surgical pain impacts many patient outcomes. Effective pain management increasingly relies on multimodal analgesia regimens in which acetaminophen (APAP) is a key component. The aim of our study was to examine the impact of oral APAP versus intravenous (IV) APAP as a component of post-surgical pain management after Cesarean sections and hysterectomies.

Methods

A retrospective analysis of the Cerner HealthFacts® database (from January, 2011 to December, 2015) was conducted to compare outcomes of Cesarean section and hysterectomy surgery patients who received oral APAP to those who received IV APAP post-surgically. Length of stay (LOS), daily morphine milligram equivalent (MME) consumption, the presence of potential opioid-related adverse events (ORADEs), and total pharmacy costs were assessed. Adjusted results were derived using inverse probability weighted regression adjustment (IPW-RA) estimators based on covariates that included demographics, comorbidities, patient clinical characteristics, and hospital characteristics.

Results

The study identified 29,124 Cesarean section patients (24,612 oral APAP; 4,512 IV APAP) and 9,767 hysterectomy surgery patients (5,586 oral APAP; 4,181 IV APAP). Compared to the oral APAP group, the IV APAP group had reductions in adjusted LOS (Cesarean section: -11.7% days (P < 0.001), hysterectomy: -11.8% days (P = 0.005)), lowered adjusted daily MME consumption from day 0 to day 3 (Cesarean section: -1.6 mg (P < 0.001), hysterectomy: -1.7 mg (P = 0.014)), and reduced risk of ORADEs for Cesarean sections (relative risk of 0.45, P < 0.001). Total pharmacy costs were not significantly different between the two APAP groups.

Conclusions

Post-surgical pain managed with IV APAP in patients undergoing Cesarean section or hysterectomy was associated with shorter LOS, reduced risk of ORADEs, and lower opioid consumption compared to patients managed with oral APAP, without adversely impacting total pharmacy costs.

Incidence and association factors for the development of chronic post-hysterectomy pain at 4- and 6-month follow-up: a prospective cohort study

Chronic pain has major adverse effects on health-related quality of life and contributes to significant socioeconomic burden. Hysterectomy is a very common gynecological surgery, resulting in chronic post-hysterectomy pain (CPHP), an important pain syndrome. We conducted a prospective cohort study in 216 Asian women who underwent abdominal or laparoscopic hysterectomy for benign conditions. Demographic, psychological, and perioperative data were recorded. Postoperative 4- and 6-month phone surveys were conducted to assess the presence of CPHP and functional impairment. The incidence rates of CPHP at 4 and 6 months were 32% (56/175) and 15.7% (25/159), respectively. Women with CPHP at 4 and 6 months had pain that interfered with their activities of daily living. Independent association factors for CPHP at 4 months were higher mechanical temporal summation score, higher intraoperative morphine consumption, higher pain score in the recovery room, higher pain score during coughing and itching at 24 hours postoperatively, and preoperative pain in the lower abdominal region. Independent association factors for CPHP at 6 months were preoperative pain during sexual intercourse, higher mechanical temporal summation score, and higher morphine consumption during postoperative 24 and 48 hours. In a majority of cases, CPHP resolved with time, but may have significant impact on activities of daily living.

Chronification of Pain: Mechanisms, Current Understanding, and Clinical Implications

PURPOSE OF REVIEW

The development of acute to chronic pain involves distinct pathophysiological changes in the peripheral and central nervous systems. This article reviews the mechanisms, etiologies, and management of chronic pain syndromes with updates from recent findings in the literature.

RECENT FINDINGS

Chronic post-surgical pain (CPSP) is not limited to major surgeries and can develop after smaller procedures such as hernia repairs. While nerve injury has traditionally been thought to be the culprit for CPSP, it is evident that nerve-sparing surgical techniques are not completely preventative. Regional analgesia and agents such as ketamine, gabapentinoids, and COX-2 inhibitors have also been found to decrease the risks of developing chronic pain to varying degrees. Yet, given the correlation of central sensitization with the development of chronic pain, it is reasonable to utilize aggressive multimodal analgesia whenever possible. Development of chronic pain is typically a result of peripheral and central sensitization, with CPSP being one of the most common presentations. Using minimally invasive surgical techniques may reduce the risk of CPSP. Regional anesthetic techniques and preemptive analgesia should also be utilized when appropriate to reduce the intensity and duration of acute post-operative pain, which has been correlated with higher incidences of chronic pain.

Patient Reported Pain After Successful Nonunion Surgery: Can We Completely Eliminate It?

OBJECTIVES

To investigate what factors are associated with continued long-term pain after fracture nonunion surgery.

DESIGN

Prospective cohort study.

SETTING

Single Academic Institution.

PATIENTS/PARTICIPANTS

Three hundred forty-one patients surgically treated for fracture nonunion were prospectively followed. Demographics, radiographic evaluations, VAS pain scores, and short musculoskeletal functional assessment (SMFA) scores were collected at routine intervals. Only patients who had a minimum of 1-year follow-up and complete healing were included this analysis. Patients were divided into a high-pain and low-pain cohort for comparison. Inclusion criteria for the high-pain cohort were defined as any patient who reported a pain score greater than one standard deviation above the mean.

MAIN OUTCOME MEASURES

Long-term VAS pain scores and factors contributing to increased patient-reported long-term VAS pain scores.

RESULTS

Two hundred seventy patients met criteria and were included in this analysis, with 223 patients (82.6%) in the low-pain cohort and 47 patients (17.4%) in the high-pain cohort. The mean long-term pain score was 7.47 ± 1.2 in the high-pain group and 1.78 ± 1.9 in the low-pain group. Within the high-pain cohort, 55.6% of patients reported a net increase in pain from baseline to long-term follow-up compared with 10.5% in the low-pain cohort (P < 0.0005). High baseline pain score (P = 0.003), increased Charlson comorbidity index (CCI) (P = 0.008), lower income level (P = 0.014), and current smoking status (P = 0.033) were found to be significantly more prevalent in the high-pain cohort.

CONCLUSIONS

Patients with higher baseline pain scores, elevated Charlson comorbidity index, lower income level or history of smoking are at an increased risk of reporting significant and potentially debilitating long-term pain after nonunion surgery. Although patients may expect complete relieve of pain, orthopaedic surgeons must inform patients of the possibility of experiencing pain 1 year or more postoperatively.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Ankle Nerve Block Adjuvant to General Anesthesia Reduces Postsurgical Pain and Improves Functional Outcomes in Hallux Valgus Surgery

OBJECTIVE

Postoperative pain is a frequent problem after orthopedic procedures like hallux valgus surgery. The aim of this study was to evaluate whether ankle block improves early and mid-term functional outcomes and postoperative pain management after hallux valgus surgery in patients receiving general anesthesia.

SUBJECTS AND METHODS

This randomized controlled trial investigated 60 patients who underwent hallux valgus surgery under general anesthesia. Patients were prospectively randomized into 2 groups: general anesthesia only (group A) and ankle block added to general anesthesia (group B). Age, body-mass index, tourniquet time, duration of surgery, first analgesic need time, perioperative analgesic regimen, visual analog scale (VAS), American Orthopedic Foot and Ankle Score (AOFAS), and length of hospital stay were recorded. Independent variables were analyzed by t test. Nonparametric data were analyzed by the Mann-Whitney U test.

RESULTS

Patient age, demographics, and body mass indices were similar between the 2 groups. The average length of hospital stay was significantly longer in group A (p < 0.01). Group B had a longer time to first analgesic need than group A (p < 0.01). Patients in group B required less analgesic during the postoperative period. Preoperative VAS and AOFAS scores were not statistically dif ferent between the 2 groups. The postoperative day 1 VAS score was significantly lower in group B than in group A. Follow-up visits at 3, 6, and 12 months showed significantly lower VAS and higher AOFAS scores in group B than group A.

CONCLUSION

Ankle block added to general anesthesia may improve early and mid-term postoperative functional outcomes and postoperative pain management in patients who undergo hallux valgus surgery.

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.

Consensus Statement for Clinical Pathway Development for Perioperative Pain Management and Care Transitions

The perioperative surgical home (PSH) model has been created with the intention to reduce costs and to improve efficiency of care and patient experience in the perioperative period. The PSH is a comprehensive model of care that is team-based and patient-centric. The team in each facility should be multidisciplinary and include the input of perioperative services leadership, surgical services, and support personnel in order to provide seamless care for the patient from the preoperative period when decision to undergo surgery is initially made to discharge and, if needed after discharge from the hospital, until full recovery is achieved. PSH is discussed in this consensus article with the emphasis on perioperative care coordination of patients with chronic pain conditions. Preoperative optimization can be successfully undertaken through patient evaluation, screening, and education. Many important positive implications in the PSH model, in particular for those patients with increased potential morbidity, mortality, and high-risk populations, including those with a history of substance abuse or anxiety, reflect a more modern approach to health care. Newer strategies, such as preemptive and multimodal analgesic techniques, have been demonstrated to reduce opioid consumption and to improve pain relief. Continuous catheters, ketamine, methadone, buprenorphine, and other modalities can be best delivered with the expertise of an anesthesiologist and a support team, such as an acute pain care coordinator. A physician-led PSH is a model of care that is patient-centered with the integration of care from multiple disciplines and is ideally suited for leadership from the anesthesia team. Optimum pain control will have a significant positive impact on the measures of the PSH, including lowering of complication rates, lowering of readmissions, improved patient satisfaction, reduced morbidity and mortality, and shortening of hospital stays. All stakeholders should work together and consider the PSH model to ensure the best quality of health care for patients undergoing surgery in the future. The pain management physician's role in the postoperative period should be focused on providing optimal analgesia associated with improved patient satisfaction and outcomes that result in reduced health care costs.

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.

Poorly controlled postoperative pain: prevalence, consequences, and prevention

This review provides an overview of the clinical issue of poorly controlled postoperative pain and therapeutic approaches that may help to address this common unresolved health-care challenge. Postoperative pain is not adequately managed in greater than 80% of patients in the US, although rates vary depending on such factors as type of surgery performed, analgesic/anesthetic intervention used, and time elapsed after surgery. Poorly controlled acute postoperative pain is associated with increased morbidity, functional and quality-of-life impairment, delayed recovery time, prolonged duration of opioid use, and higher health-care costs. In addition, the presence and intensity of acute pain during or after surgery is predictive of the development of chronic pain. More effective analgesic/anesthetic measures in the perioperative period are needed to prevent the progression to persistent pain. Although clinical findings are inconsistent, some studies of local anesthetics and nonopioid analgesics have suggested potential benefits as preventive interventions. Conventional opioids remain the standard of care for the management of acute postoperative pain; however, the risk of opioid-related adverse events can limit optimal dosing for analgesia, leading to poorly controlled acute postoperative pain. Several new opioids have been developed that modulate μ-receptor activity by selectively engaging intracellular pathways associated with analgesia and not those associated with adverse events, creating a wider therapeutic window than unselective conventional opioids. In clinical studies, oliceridine (TRV130), a novel μ-receptor G-protein pathway-selective modulator, produced rapid postoperative analgesia with reduced prevalence of adverse events versus morphine.