Persistent pain after caesarean section and its association with maternal anxiety and socioeconomic background

Sleep quality as a mediator of the relation between depression and chronic pain: a systematic review and meta-analysis

BACKGROUND

Chronic pain and depression represent two global health problems with considerable economic consequences. Although existing literature reports on the relation between depression and pain conditions, meta-analytic evidence backing the mediating role of sleep disturbance as one of the main symptoms of depression is scarce. To examine the extent to which sleep disturbance mediates the depression-chronic pain association, we conducted a systematic review and meta-analysis of the associations of chronic pain, depression, and sleep quality.

METHODS

We systematically searched for literature in MEDLINE and other relevant databases and identified cohort and case-control studies on depression, sleep disturbance, and chronic pain. Forty-nine studies were eligible, with a total population of 120 489 individuals. We obtained direct and indirect path coefficients via two-stage meta-analytic structural equation modelling, examined heterogeneity via subgroup analyses, and evaluated primary studies quality.

RESULTS

We found a significant, partial mediation effect of sleep disturbance on the relation between depression and chronic pain. The pooled path coefficient (coef.) of the indirect effect was 0.03 (95% confidence interval [CI]: 0.01-0.05) and accounted for 12.5% of the total effect of depression on chronic pain. This indirect effect also existed for cohort studies (coef. 0.02; 95% CI: 0.002-0.04), European studies (coef. 0.03; 95% CI: 0.004-0.05), and studies that adjusted for confounders (coef. 0.04; 95% CI: 0.01-0.09).

CONCLUSIONS

Sleep disturbance partially mediates the association between depression and pain. Although plausible mechanisms could explain this mediation effect, other explanations, including reverse causation, must be further explored.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42022338201.

The role of expectations, subjective experience, and pain in the recovery from an elective and emergency caesarean section: A structural equation model

BACKGROUND

Rapid return to mobilisation and daily function is essential for recovery after an elective and emergency caesarean section, prevention of short- and long-term complications, and mothers' well-being. High pain levels may delay recovery. Considering the biopsychosocial model, recovery is additionally complex and comprises social and psychological aspects.

OBJECTIVE

This study examined the relationships between preoperative expectations, perioperative subjective experience, postoperative pain levels, and postoperative interruption of functioning and recovery.

METHODS

Overall, 306 women completed a set of questionnaires on the fourth day after a caesarean section regarding their demographic information, levels of expectation matching the caesarean section and the perioperative subjective experience, and the pain levels and interruption to daily activities 24 hours postpartum.

RESULTS

Using a structural equation model, a gap between preoperative expectations and perioperative experience related to a poorer perioperative subjective experience was found. This was associated with higher postoperative pain levels that were directly and indirectly related to the interruption of various functions and activities during the initial 24 hours postpartum. The model explained 58% of the variance in postpartum functioning and had good goodness-of-fit (χ2 = 242.74, df = 112, χ2/df = 2.17, NFI = 0.93, CFI = 0.96, TLI = 0.94, RMSEA = 0.06). Additionally, pain levels were higher and daily activities were more severely impaired for women who had undergone emergency caesarean section compared to those who had undergone elective caesarean section.

CONCLUSION

The need for preoperative preparation and setting expectations, perioperative emotional support, continuous communication with the mother, and an efficient postoperative pain management was highlighted.

Association of pain, analgesic, psychological, and socioeconomic factors with sub-acute pain after childbirth: A prospective cohort study

STUDY OBJECTIVE

To determine if acute postpartum pain, psychological distress, socioeconomic factors, and labor analgesia were associated with sub-acute pain after childbirth (SAPC; pain starting after childbirth and lasting between four weeks to three months).

DESIGN

Prospective cohort study, from pre-conception to post-partum three months.

SETTING

Singapore's major public maternity institution.

PATIENTS

We included women planning to conceive within a year. We excluded women who were pregnant, taking chemotherapy or psychotropic medications, had diabetes mellitus, received assisted fertility interventions or contraception, did not conceive after 12 months, with multiple pregnancies, or who developed obstetric complications.

INTERVENTIONS

None.

MEASUREMENTS

We investigated the relationship between average pain score during the three days after childbirth (primary exposure) and incidence of SAPC at postpartum three months (primary outcome). Secondarily, psychological distress at pre-conception (Beck Depression Inventory (BDI), Edinburgh Postnatal Depression Scale (EPDS), State-Trait Anxiety Inventory (STAI), Perceived Stress Scale (PSS), General Health Questionnaire-12 (GHQ-12), Life Experiences Survey (LES)) and second trimester of pregnancy (BDI, EPDS, STAI, PSS, Pregnancy Experience Scale (PES)) were assessed. Baseline maternal and socioeconomic characteristics, labor analgesia, maternal and neonatal outcomes were also collected accordingly.

MAIN RESULTS

Of 317 women who met the study criteria, 30 (9.5%) developed SAPC. Higher average pain score during the three days after childbirth (adjusted odds ratio (aOR) 1.46, 95% CI 1.17 to 1.82, p = 0.001), use of meperidine for labor analgesia (aOR 4.23, 95% CI 1.03 to 17.43, p = 0.046), higher pre-conception GHQ-12 score (aOR 1.14, 95% CI 1.03 to 1.27, p = 0.013), and lack of employment with income during pregnancy (aOR 9.62, 95% CI 3.07 to 30.30, p < 0.001) were independently associated with SAPC, with area under the curve (AUC) of 0.837.

CONCLUSIONS

Higher acute postpartum pain scores, use of meperidine for labor analgesia, poorer pre-conception general psychological health, and lack of employment with income during pregnancy are associated with SAPC.

Analgesia Effect of Ultrasound-Guided Transversus Abdominis Plane Block Combined with Intravenous Analgesia After Cesarean Section: A Double-Blind Controlled Trial

INTRODUCTION

Complete postoperative analgesia is very important for puerperae after cesarean section. The objective of this study was to explore the optimal postoperative analgesia after cesarean section.

METHODS

A total of 180 full-term puerperae who underwent cesarean section in Hanzhong People's Hospital from March 2019 to March 2020 were enrolled and were randomly divided into three groups. Group A was given 0.9% normal saline, group B and C were given 0.4% ropivacaine for transversus abdominis plane block (TAPB). Postoperative patient-controlled intravenous analgesia (PCIA) pumps were 2 μg/kg sufentanil + 2.5 mg droperidol, 1.5 μg/kg and 1.3 μg/kg sufentanil, respectively. All puerperae were given different but effective analgesia programs. The primary outcome indicators were visual analog scores (VAS), the first compression time of postoperative analgesia pump and the total number of compressions in 48 h. The secondary outcome indicators were vital signs, Ramsay sedation scores, comfort scores (BCS), the frequency of analgesic rescue, postoperative side effects and satisfaction.

RESULTS

The dynamic and static VAS scores of the puerperae in group B at T₂ and T₆ were significantly lower than group A and at T₁₂, T₂₄ and T₄₈ were significantly lower than group C. Compared with group A, the dynamic and static VAS scores of puerperae in group C were lower at T₂ and T₆ and higher at T₁₂, T₂₄ and T₄₈. The Ramsay score and BCS score of the puerperae in group C at T₁₂, T₂₄ and T₄₈ were significantly lower than those in groups A and B.

CONCLUSIONS

PCIA with sufentanil alone or combined with TAPB can be safely and effectively used for postoperative analgesia after cesarean section. PCIA combined with TAPB had better analgesic effect and lower incidence of side effects while reducing the dose of opioids. The results of this study provide new ideas and insights for the choice of analgesia after cesarean section.

The Effects of Antepartum Depressive Symptoms on Postcesarean Opioid Consumption

OBJECTIVE

The study aimed to test the hypothesis that higher Edinburgh Postnatal Depression Scale (EPDS) scores are associated with increased pain scores and opioid use during postpartum hospitalization following cesarean section.

STUDY DESIGN

We conducted a retrospective cohort of English or Spanish-speaking women ≥18 years who had prenatal care for a singleton gestation and delivered by cesarean at ≥36 weeks within a tertiary center during 2017. Exclusions included women with fetal anomalies, intrauterine fetal demise, sickle cell disease, previously diagnosed pain disorders (e.g., chronic pain or fibromyalgia), substance use disorder (based on documented prescription or use of methadone or buprenorphine), or reoperation during hospital stay. Women without an EPDS recorded antenatally were also excluded. Major depressive symptoms (MDS) were defined as a documented antenatal EPDS ≥12. Women with and without MDS were compared, and multivariable linear regression models were generated to evaluate associations between MDS status and both pain scores and opioid use.

RESULTS

Of the 891 women meeting other inclusion criteria, 676 (76%) had documented antenatal EPDS scores, and 104 (15.4%) of those had MDS. Women with MDS were more likely to be use tobacco and have general anesthesia for cesarean delivery, but groups were otherwise similar. Women with MDS reported higher daily and average pain scores postpartum (2.4 vs. 1.7 average; p < 0.001). Women with MDS used more morphine milligram equivalents (MME) each day during their postpartum hospitalization, leading to a higher total MME use (121 mg [60.5-214.5] vs. 75 mg [28.5-133.5], p < 0.001).

CONCLUSION

We found an association between antepartum depressive symptoms and acute pain after cesarean delivery leading to increased opioid use. Given the current focus on opioid stewardship, further research into this association, exploration of tailored pain control, and determining whether treatment of antepartum MDS reduces postpartum pain, and therefore opioid use, will be of the utmost priority.

KEY POINTS

· Women with MDS report higher pain scores postcesarean.. · Women with MDS use more opioids postcesarean.. · Future studies are needed for the treatment of MDS..

Anxiety, Depression, and Pain in the Perinatal Period: A Review for Obstetric Care Providers

Importance

Maternal depression and anxiety may not only increase vulnerability for the development of postpartum depression and anxiety but may increase the perception of obstetric pain.

Objective

This review focuses on the relationship among depression, anxiety, and pain during pregnancy and postpartum. We will first review common clinical screening tools for depression, anxiety, and pain. Then, the existing evidence describing the relationship of depression, anxiety, and pain will be covered.

Evidence Acquisition

Queries for publications in PubMed, Google Scholar, and the CINAHL (Cumulative Index to Nursing and Allied Health Literature) were completed. Both searches were limited to publications within the last 20 years. Literatures on subtopics obtained from the references of publications identified in the initial search were not limited by publication year.

Results

A total of 19 total publications were identified regarding postpartum depression and pain; 17 were identified in the initial search, and 2 related to postpartum depression, anxiety, and pain were found by reviewing references. Eleven studies were identified regarding postpartum anxiety and pain; 4 were found in the original search, and 7 were identified by reviewing the references.

Conclusions and Relevance

The relationship between postpartum depression and pain is well characterized in the literature. However, the relationship between postpartum anxiety and pain is less well defined, and further research is needed. The interaction between maternal mental health and pain emphasizes the importance of screening for these conditions and also counseling and educating patients about expectations regarding intrapartum and postpartum pain.

Sociodemographic predictors of attendance at a Scottish pain management programme

We examined relationships between various sociodemographic factors and attendance at the Glasgow Pain Management Programme (n = 2899 from 2011 to 2019). We tested for associations between gender, age and socioeconomic deprivation of patients who were invited to attend, and uptake to a programme when invited, attendance at screening assessment, eligibility, adherence and attendance at 3- and 6-month reviews. Uptake was significantly higher for patients from more affluent areas (95% confidence interval (CI) = 0.93–0.99, p = 0.002) and for older patients (95% CI = 0.98–0.99, p = 0.006), although effect sizes were very small. Patients were significantly more likely to be assessed as suitable if they were younger (95% CI = 0.98–0.99, p = 0.013) or female (95% CI = 0.55–0.84, p < 0.001). Attendance at sessions and at 3- and 6-month reviews was higher for patients from more affluent areas (95% CI = 1–1.09, p = 0.001, and 95% CI = 1–1.1, p = 0.044 respectively). We argue that there are multiple potential explanations for these findings and that future work should attempt to determine whether these patterns replicate in other populations and to determine any modifiable causes.

Separation from a bonded partner alters neural response to inflammatory pain in monogamous rodents

Pain experience is known to be modified by social factors, but the brain mechanisms remain unspecified. We recently established an animal model of social stress-induced hyperalgesia (SSIH) using a socially monogamous rodent, the prairie vole, in which males separated from their female partners (loss males) became anxious and displayed exacerbated inflammatory pain behaviors compared to males with partners (paired males). In the present study, to explore the neural pathways involved in SSIH, a difference in neuronal activation in pain-related brain regions, or "pain matrix", during inflammatory pain between paired and loss males was detected using Fos immunoreactivity (Fos-ir). Males were paired with a female and pair bonding was confirmed in all subjects using a partner preference test. During formalin-induced inflammatory pain, both paired and loss males showed a significant induction of Fos-ir throughout the analyzed pain matrix components compared to basal condition (without injection), and no group differences in immunoreactivity were found among the injected males in many brain regions. However, the loss males had significantly lower Fos-ir following inflammatory pain in the medial prefrontal cortex and nucleus accumbens shell than the paired males, even though base Fos-ir levels were comparable between groups. Notably, both regions with different Fos-ir are major components of the dopamine and oxytocin systems, which play critical roles in both pair bonding and pain regulation. The present results suggest the possibility that pain exacerbation by social stress emerges through alteration of signaling in social brain circuitry.

Neuropathic component of postoperative pain for predicting post-caesarean chronic pain at three months. A prospective observational study

BACKGROUND

Recent investigations have showed that caesarean section (CS) might be a cause of chronic pain, with a consequent decrease in quality of life.

METHODS

Prospective observational study in a Spanish tertiary hospital. Main Outcome measure was to assess early neuropathic characteristics of pain (DN2 score ≥ 3) one week after CS as a potential risk factor for post-caesarean section chronic pain (PCSCP) at three months. Secondary outcome was to identify other risk factors. 610 consecutive consenting patients undergoing CS were interviewed preoperatively, at discharge from recovery room and 24h postoperatively. Telephone follow-up interviews were conducted one week, three months and twelve months following surgery.

RESULTS

We analysed 597 consecutive patients. The incidence of PCSCP at three and twelve postoperative months were 6.2% and 1% respectively. Subjects with NRS score superior to five on movement one week after CS presented higher incidence of PCSCP (NRS superior to five: 19 (52,2%); NRS equal or lower to five: 172 (30,9%); p=0,009). On multivariate analysis neuropathic pain one week after CS was associated with a higher risk of PCSCP (AOR: 1.63 (95% CI: 1.26-2.11; p<0.001). Other identified risk factors for PCSCP were: uterine exteriorization during CS (AOR: 3.89 (95% CI 1.25-12.10; p=0.019) and a lower gestational age (AOR: 0.87 (95% CI: 0.78-0.96; p=0.008).

CONCLUSIONS

Incidence of PCSCP at three and twelve postoperative months was low, 6.2% and 1% respectively. Early neuropathic characteristics of pain after one week measured by neuropathic pain questionnaire, consisting of two questions (DN2) ≥ 3/7 could be used to identify patients at risk for chronic post-surgical pain and develop preventive strategies.

During capsaicin-induced central sensitization, brush allodynia is associated with baseline warmth sensitivity, whereas mechanical hyperalgesia is associated with painful mechanical sensibility, anxiety and somatization

BACKGROUND

Mechanical hyperalgesia and allodynia incidence varies considerably amongst neuropathic pain patients. This study explored whether sensory or psychological factors associate with mechanical hyperalgesia and brush allodynia in a human experimental model.

METHODS

Sixty-six healthy volunteers (29 male) completed psychological questionnaires and participated in two quantitative sensory testing (QST) sessions. Warmth detection threshold (WDT), heat pain threshold (HPT) and suprathreshold mechanical pain (STMP) ratings were measured before exposure to a capsaicin-heat pain model (C-HP). After C-HP exposure, brush allodynia and STMP were measured in one session, whilst mechanical hyperalgesia was measured in another session.

RESULTS

WDT and HPT measured in sessions separated by 1 month demonstrated significant but moderate levels of reliability (WDT: ICC = 0.5, 95%CI [0.28, 0.77]; HPT: ICC = 0.62, 95%CI [0.40, 0.77]). Brush allodynia associated with lower WDT (z = -3.06, p = 0.002; ϕ = 0.27). Those with allodynia showed greater hyperalgesia intensity (F = 7.044, p = 0.010, η_p ²  = 0.107) and area (F = 9.319, p = 0.004, η_p ²  = 0.163) than those without allodynia. No psychological self-report measures were significantly different between allodynic and nonallodynic groups. Intensity of hyperalgesia in response to lighter mechanical stimuli was associated with lower HPT, higher STMP ratings and higher Pain Sensitivity Questionnaire scores at baseline. Hyperalgesia to heavier probe stimuli associated with state anxiety and to a lesser extent somatic awareness. Hyperalgesic area associated with lower baseline HPT and higher STMP ratings. Hyperalgesic area was not correlated with allodynic area across individuals.

CONCLUSIONS

These findings support research in neuropathic pain patients and human experimental models that peripheral sensory input and individual sensibility are related to development of mechanical allodynia and hyperalgesia during central sensitization, whilst psychological factors play a lesser role.

SIGNIFICANCE

We evaluated differential relationships of psychological and perceptual sensitivity to the development of capsaicin-induced mechanical allodynia and hyperalgesia. Fifty percent of healthy volunteers failed to develop mechanical allodynia. Baseline pain sensitivity was greater in those developing allodynia and was related to the magnitude and area of hyperalgesia. State psychological factors, whilst unrelated to allodynia, were related to mechanical hyperalgesia. This supports that the intensity of peripheral sensory input and individual sensibility are related to development of mechanical allodynia and hyperalgesia during central sensitization, whilst psychological factors play a lesser role.

The impact of a transversus abdominis plane block including clonidine vs. intrathecal morphine on nausea and vomiting after caesarean section: A randomised controlled trial

BACKGROUND

Intrathecal morphine (ITM) is a widely used technique for postcaesarean section analgesia but entails a high risk of postoperative nausea and vomiting (PONV). The transversus abdominis plane (TAP) block is an alternative.

OBJECTIVE

We tested the hypothesis that a TAP block including clonidine reduces the incidence of PONV after caesarean section when compared with ITM.

DESIGN

A randomised, controlled, double-blinded study.

SETTING

Geneva University Hospitals, Switzerland, from October 2013 to February 2017.

PATIENTS

A total of 182 patients undergoing elective caesarean section were studied. Reasons for noninclusion were complicated pregnancy, contraindication to spinal anaesthesia or TAP block, extreme weight or height, allergy to any medication or previous median abdominal incision.

INTERVENTIONS

Patients were allocated randomly to one of two groups (quadruple blinded): 100 μg of morphine added to the spinal local anaesthetic or a bilateral TAP block with 20 ml of ropivacaine 0.375% + 75 μg of clonidine on each side.

MAIN OUTCOME MEASURES

The primary outcome measure was the total number of patients presenting with PONV at 24 h. Secondary aims were to compare other adverse effects (pruritus, respiratory depression, hypotension, bradycardia, sedation), analgesic efficacy and the quality of postoperative recovery.

RESULTS

At 24 h, there was no significant difference between ITM and TAP groups in the total number of patients presenting with PONV: 17/92 patients (18.5%, 95% confidence interval 11.1 to 27.9) and 27/88 patients (30.7%, 95% confidence interval 21.3 to 41.4) in TAP and ITM groups, respectively (P = 0.065). Pain scores at 6 h and cumulative morphine consumption at 24 h were lower in the ITM group (P < 0.0001 for morphine consumption at 24 h). The incidence of hypotension was higher in the TAP group (54.3 vs. 29.2%, P = 0.0006). Maternal satisfaction was high and not different between groups.

CONCLUSION

A TAP block with clonidine and local anaesthetic does not reduce significantly the incidence of PONV compared with ITM. We confirm the superiority of ITM on acute postcaesarean section analgesia compared with a TAP block, even with clonidine as an adjunct.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01931215.

Acute postoperative pain is correlated with the early onset of postpartum depression after cesarean section: a retrospective cohort study

The primary purpose of this study was to evaluate the correlation between the intensity of acute postoperative pain and development of postpartum depression (PPD) after cesarean section (CS). The secondary purpose was to investigate perioperative risk factors for PPD detected in the postoperative period after CS. We retrospectively reviewed 615 women who had undergone CS between January 2017 and October 2019 in our hospital. The incidence of PPD was 22.7% on postoperative day (POD) 5 in the 247 women whose numerical rating scale (NRS) scores on POD3 were available. The severity of acute postoperative pain evaluated by NRS was higher in women with than in those without PPD on POD3 (P < 0.02). The independent risk factors for the onset of PPD on POD5 were being a primipara [adjusted odds ratio (aOR), 2.08; 95% confidence interval (CI), 1.03-4.20, P < 0.05], preoperative presence of chronic pain (OR, 4.44; 95% CI 1.82-10.81, P < 0.001), and NRS ≥ 2 on POD3 (aOR, 4.90; 95% CI 1.06-22.61, P < 0.05). Our findings suggest that assessing both acute postoperative pain and presence of PPD can inform the introduction of interventions in the early phase to prevent development of PPD after CS.

Factors associated with persistent pain after childbirth: a narrative review

A systematic literature search was performed to identify studies that reported risk factors for persistent pain after childbirth. Many studies have sought to identify risk factors for post-delivery pain in different populations, using different methodologies and different outcome variables. Studies of several different but interrelated post-partum pain syndromes have been conducted. Factors strongly and specifically associated with persistent incisional scar pain after Caesarean delivery include a coexisting persistent pain problem in another part of the body and severe acute postoperative pain. For persistent vaginal and perineal pain, operative vaginal delivery and the magnitude of perineal trauma have been consistently linked. History of pregnancy-related and pre-pregnancy back pain and heavier body weight are robust risk factors for persistent back pain after pregnancy. Unfortunately, limitations, particularly small samples and lack of a priori sample size calculation designed to detect specific effect sizes for risk of persistent pain outcomes, preclude definitive conclusions about many other predictors and the strength of outcome associations. In future studies, assessments of specific phenotypes using a rigorous analysis with appropriate predetermined sample sizes and validated instruments are needed to allow elucidation of stronger and reliable associations. Interventional studies targeting the most robustly associated, modifiable risk factors, such as acute post-partum pain, may lead to solutions for the prevention and treatment of these common problems that impact a large population.

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.

Local injection of dexamethasone helping to prevent lower back pain after epidural delivery analgesia

This report aims to retrospectively analyze the clinical effect of local pretreatment with dexamethasone (DXMS) on lower back pain after epidural labor analgesia. Patients with epidural labor analgesia treated in People's Hospital of Rizhao from January 2014 to December 2016 were studied. All 368 cases involved were pregnant primipara with full-term single birth. Parturient received injection of DXMS and lidocaine mixture around the epidural puncture point was the observation group (n=188), and parturient received injection of 0.9% sodium chloride and lidocaine mixture around the epidural puncture point was the control group (n=180). The incidence and degree of lower back pain postoperatively in the two groups were evaluated by pain visual analogue scale method. The incidence of lower back pain at 48 h, 72 h after operation in observation group was significantly lower than that in control group (p<0.05). Among patients undergoing one puncture and more than one puncture, the incidence of postoperative lower back pain in the observation group was significantly lower than that in the control group (59.26%) (p<0.05). Among the parturient with spontaneous delivery, the incidence of postoperative lower back pain in the observation group was significantly lower than that in the control group (p=0.028). Among the cesarean section patients, the incidence of pain in observation group was significantly lower than that in control group (p=0.019). At 48 and 72 h after operation, severe pain in the observation group was significantly less than that in the control group (p<0.05). DXMS local pretreatment can significantly reduce the incidence of postoperative lower back pain and the degree of pain after epidural delivery analgesia. DXMS pretreatment in epidural analgesia deserved to be widely used clinically.

Partner Loss in Monogamous Rodents: Modulation of Pain and Emotional Behavior in Male Prairie Voles

OBJECTIVE

Pain is modulated by psychosocial factors, and social stress-induced hyperalgesia is a common clinical symptom in pain disorders. To provide a new animal model for studying social modulation of pain, we examined pain behaviors in monogamous prairie voles experiencing partner loss.

METHODS

After cohabitation with novel females, males (n = 79) were divided into two groups on the basis of preference test scores. Half of the males of each group were separated from their partner (loss group), whereas the other half remained paired (paired group). Thus, males from both groups experienced social isolation. Open field tests, plantar tests, and formalin tests were then conducted on males to assess anxiety and pain-related behaviors.

RESULTS

Loss males showing partner preferences (n = 20) displayed a significant increase in anxiety-related behavior in the open-field test (central area/total distance: 13.65% [1.58%] for paired versus 6.45% [0.87%] for loss; p < .001), a low threshold of thermal stimulus in the plantar test (withdrawal latencies: 9.69 [0.98] seconds for paired versus 6.15 [0.75] seconds for loss; p = .037), and exacerbated pain behaviors in the formalin test (total number of lifts: 40.33 [4.46] for paired versus 54.42 [1.91] for loss; p = .042) as compared with paired males (n = 20). Thermal thresholds in the plantar test significantly correlated with anxiety-related behavior in the open-field test (r = 0.64). No such differences were observed in the males that did not display partner preferences (r = 0.15).

CONCLUSIONS

Results indicate that social bonds and their disruption, but not social housing without bonding followed by isolation, modulate pain and emotion in male prairie voles. The prairie vole is a useful model for exploring the neural mechanisms by which social relationships contribute to pain and nociceptive processing in humans.