Ovarian hormones and chronic pain: A comprehensive review

The role of gonadal hormones in regulating opioid antinociception

Opioids are the most prescribed drugs for the alleviation of pain. Both clinical and preclinical studies have reported strong evidence for sex-related divergence regarding opioid analgesia. There is an increasing amount of evidence indicating that gonadal hormones regulate the analgesic efficacy of opioids. This review presents an overview of the importance of gonadal steroids in modulating opioid analgesic responsiveness and focuses on elaborating what is currently known regarding the underlyingmechanism. We sought to identify the link between gonadal hormones and the effect of oipiod antinociception.

Activation of GABAergic neurons in the dorsal raphe nucleus alleviates hyperalgesia induced by ovarian hormone withdrawal

ABSTRACT

Menopausal and postmenopausal women, characterized by a significant reduction in ovarian hormones, have a high prevalence of chronic pain with great pain intensity. However, the underlying mechanism of hyperalgesia induced by ovarian hormone withdrawal remains poorly understood. Here, we report that decreases in the activity and excitability of GABAergic neurons in the dorsal raphe nucleus (DRN) are associated with hyperalgesia induced by ovariectomy in mice. Supplementation with 17β-estradiol, but not progesterone, is sufficient to increase the mechanical pain threshold in ovariectomized (OVX) mice and the excitability of DRN GABAergic (DRNGABA) neurons. Moreover, activation of the DRNGABA neurons projecting to the lateral parabrachial nucleus was critical for alleviating hyperalgesia in OVX mice. These findings show the essential role of DRNGABA neurons and their modulation by estrogen in regulating hyperalgesia induced by ovarian hormone withdrawal, providing therapeutic basis for the treatment of chronic pain in physiological or surgical menopausal women.

Hyperglycemia and Central Obesity Disrupt Conditioned Pain Modulation: A Single-Blind Crossover Randomized Controlled Trial

Hyperglycemia and high adiposity are risk factors for pain in diabetes. To clarify these links with pain, the effects of a glucose load on sensory detection, pain sensitivity, conditioned pain modulation (primary aims), and autonomic and endothelial functions (secondary aims) were examined in 64 pain-free participants: 22 with normal adiposity (determined by dual-energy X-ray absorptiometry), 29 with high adiposity, and 13 with combined high adiposity and elevated glycated hemoglobin (HbA1c; including prediabetes and type 2 diabetes). Participants ingested either 37.5 g glucose or 200 mg sucralose (taste-matched) in the first session and crossed over to the other substance in the second session 1 month later. At baseline, painful temple cooling (the conditioning stimulus) inhibited pressure- and heat-pain in the ipsilateral arm (the test stimuli) immediately after cooling ceased (partial η2's > .32). Glucose ingestion weakened pressure-pain inhibition irrespective of HbA1c levels (partial η2 = .11). However, a larger reduction in pressure-pain inhibition after ingesting glucose was associated with a higher waist/hip ratio (r = .31), suggesting a role of central obesity. Heat-pain inhibition was absent at baseline in unmedicated participants with elevated HbA1c, and these participants reported more occlusion-induced pain after ingesting glucose (partial η2's > .17). Glucose ingestion interfered with parasympathetic activity in all participants (partial η2 = .11) but did not affect endothelial function (measured by reactive hyperemia) or alter other sensations (eg, feet vibration detection). The disruptive effect of hyperglycemia on conditioned pain modulation increases in line with central obesity, which might facilitate pain in diabetes. PERSPECTIVE: Ingesting 37.5 g glucose (approximately 350 mL soft drink) interfered with pain modulation in pain-free adults with normal adiposity or with combined high adiposity and HbA1c levels. The interference was stronger alongside increasing central obesity, suggesting that controlling blood glucose and body fat mass might help preserve pain modulation.

Pain mechanisms in the transgender individual: a review

Specific Aim

Provide an overview of the literature addressing major areas pertinent to pain in transgender persons and to identify areas of primary relevance for future research.

Methods

A team of scholars that have previously published on different areas of related research met periodically though zoom conferencing between April 2021 and February 2023 to discuss relevant literature with the goal of providing an overview on the incidence, phenotype, and mechanisms of pain in transgender patients. Review sections were written after gathering information from systematic literature searches of published or publicly available electronic literature to be compiled for publication as part of a topical series on gender and pain in the Frontiers in Pain Research.

Results

While transgender individuals represent a significant and increasingly visible component of the population, many researchers and clinicians are not well informed about the diversity in gender identity, physiology, hormonal status, and gender-affirming medical procedures utilized by transgender and other gender diverse patients. Transgender and cisgender people present with many of the same medical concerns, but research and treatment of these medical needs must reflect an appreciation of how differences in sex, gender, gender-affirming medical procedures, and minoritized status impact pain.

Conclusions

While significant advances have occurred in our appreciation of pain, the review indicates the need to support more targeted research on treatment and prevention of pain in transgender individuals. This is particularly relevant both for gender-affirming medical interventions and related medical care. Of particular importance is the need for large long-term follow-up studies to ascertain best practices for such procedures. A multi-disciplinary approach with personalized interventions is of particular importance to move forward.

Clinical features of chronic primary pain in individuals presenting painful temporomandibular disorder and comorbidities

BACKGROUND

The diagnosis of chronic primary pain (CPP), according to the recently released International Classification of Disease (ICD-11) criteria, refers to conditions with complex aetiologies. CPP is characterized by specific clinical features such as generalized sensory hypersensitivity and widespread pain, and is associated with functional disability and emotional distress.

OBJECTIVE

This study investigated clinical features of CPP in individuals with painful temporomandibular disorders (TMD) and comorbidities (fibromyalgia, migraine and/or tension-type headache).

METHODS

This cross-sectional study was conducted with a sample of 129 individuals. Painful TMD, fibromyalgia and primary headaches were evaluated based on well-established international criteria. Generalized sensory hypersensitivity was assessed using psychophysical tests. Symptoms of anxiety and depression were assessed by the Generalized Anxiety Disorder-7 and Patient Health Questionnaire-9. The Central Sensitization Inventory was applied to assess central sensitization-related symptoms and the Pittsburg Sleep Quality Index to evaluate the quality of sleep. The presence of widespread pain was assessed using a body map. The sample was stratified into three groups: control (n = 25), TMD-painful TMD only (n = 35) and TMD + Cm-painful TMD and comorbidities (n = 69). Statistical analysis was performed using one-way ANOVA, chi-squared test and ANCOVA, considering gender as a covariate (α = .05).

RESULTS

Compared to controls, individuals presenting painful TMD and comorbidities showed lower pressure pain thresholds in all evaluated areas (p ≤ .012) and a higher number of painful areas in the body (p = .001). They presented more symptoms of anxiety (p = .040) and depression (p = .018), and a higher score in the Central Sensitization Inventory (p ≤ .006) than the other groups.

CONCLUSION

Individuals with painful TMD and comorbidities presented more clinical features of CPP compared to those affected by TMD only.

Sex hormones associated with temporomandibular pain on palpation in male adolescents-Results of the epidemiologic LIFE child study

OBJECTIVE

This study aimed to investigate whether the sex steroid precursor hormone dehydroepiandrosterone sulphate (DHEA-S), sex hormone-binding globulin (SHBG) and testosterone (TT) are associated with temporomandibular (TM) pain on palpation in male adolescents.

METHODS

Out of the LIFE Child study dataset containing 1022 children and adolescents aged 10-18 years (496 males, 48.5%), we used a subsample of 273 male adolescents (mean age: 13.8 ± 2.3 years) in advanced pubertal development (PD) to analyse the association between hormones and TM pain. The Tanner scale was applied to describe the stage of PD. Pain on palpation of the temporalis and masseter muscles and the TM joints (palpation pain) was assessed using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Serum levels of sex hormones (DHEA-S, SHBG and TT) were determined using standardised laboratory analyses. Free TT was estimated from the ratio between TT and SHBG (free androgen index[FAI]). We calculated the risk of perceived positive palpation pain for male participants as a function of hormone levels (DHEA-S, FAI) taking into account age and body mass index (BMI).

RESULTS

Among more developed (Tanner stage 4-5) male adolescents, 22.7% (n = 62) reported palpation pain in the TM region. In these participants, FAI levels were approximately half that of individuals without such pain (p < .01). DHEA-S levels were about 30% lower in the pain group (p < .01). In multivariable regression analyses, the odds ratio (OR) for pain on palpation decreased to 0.75 (95% confidence interval [CI]: 0.57-0.98) per 10 units of FAI level compared to those without pain, after controlling for the effects of age and adjusted BMI. We observed the same effect for this subgroup per unit of DHEA-S serum level (OR = 0.71; 95% CI: 0.53-0.94).

CONCLUSION

At subclinical lower levels of serum free TT and DHEA-S, male adolescents are more likely to report pain on standardised palpation of the masticatory muscles and/or TM joints. This finding supports the hypothesis that sex hormones may influence pain reporting.

Changes in sex hormones and their interactions are related to pain perception between different menstrual subphases

Whether sex hormones are related to pain perception across the menstrual cycle is unclear. We examined changes in experimental pain perception in healthy young females between the early to midfollicular subphase (emF) and the midluteal subphase (mL) and explored the role of sex hormones. Sixty-six participants were involved in the study. We tested pressure pain, cold pain, ischemic pain, and needle pain, while at the same time we measured sex hormones levels in two menstrual subphases. Only the right ulna pressure test showed a significant reduction in pain threshold (PPTh3) during the mL. The absolute change of PPTh3 (PPTh3mL - PPTh3emF) was related to the absolute change of prolactin. The relative change of the range of pain tolerance for pressure pain of the right ulna (RPT3rc) was related to the relative change of progesterone (Prc) and estradiol (E2rc) levels, and the interaction effects showed that at Prc ≤ 30, E2rc was positively correlated with RPT3rc. The same, the relative change of pressure pain tolerance of the pulp of the middle finger on the right hand (PPTo4rc) was related to E2rc and Prc, and the results of the interaction between E2rc and Prc suggest that when E2rc is ≤0.8, Prc is positively correlated with PPTo4rc. Two different formulas were applied in this study and showed inconsistent results. Most pain tests showed no difference between the two subphases of the menstrual cycle. Only the relative changes of the PPTo4 and RPT3 are related to the E2rc and Prc, respectively, between menstrual subphases in an interactive way in healthy young women.

Facilitated Central Pain Mechanisms Across the Menstrual Cycle in Dysmenorrhea and Enlarged Pain Distribution in Women With Longer Pain History

Dysmenorrhea (DYS), or recurrent menstrual pain, is a highly prevalent pain condition among otherwise healthy women. However, the progression of DYS over time and the influence of the menstrual cycle phases need to be better understood. While the location and distribution of pain have been used to assess pain mechanisms in other conditions, they are unexplored in DYS. Thirty otherwise healthy women with severe DYS and 30 healthy control women were recruited into 3 subgroups (n = 10) according to the length of their menstrual history (<5, 5-15, or>15 years since menarche). The intensity and distribution of menstrual pain were recorded. Pressure pain thresholds at abdominal, hip, and arm sites, pressure-induced pain distribution, temporal summation of pain, and pain intensity after pressure cessation over the gluteus medius were assessed at 3 menstrual cycle phases. Compared with the healthy control women, those with DYS showed lower pressure pain thresholds in every site and menstrual cycle phase (P < .05), enlarged pressure-induced pain areas during menstruations (P < .01), and increased temporal summation and pain intensity after pressure cessation in the overall menstrual cycle (P < .05). Additionally, these manifestations were enhanced during the menstrual and premenstrual phases compared to ovulation in women with DYS (P < .01). Women with long-term DYS demonstrated enlarged pressure-induced pain distribution, enlarged menstrual pain areas, and more days with severe menstrual pain compared to the short-term DYS subgroup (P < .01). Pressure-induced and menstrual pain distributions were strongly correlated (P < .001). These findings suggest that severe DYS is a progressive condition underscored by facilitated central pain mechanisms associated with pain recurrence and exacerbation. PERSPECTIVE: Enlarged pressure-induced pain areas occur in DYS, associated with the length of the condition and the distribution of menstrual pain. Generalized hyperalgesia is present throughout the entire menstrual cycle and intensifies during premenstrual and menstrual phases.

Microglia and p38 MAPK Inhibitors Suppress Development of Mechanical Allodynia in Both Sexes in a Mouse Model of Antiretroviral-Induced Neuropathic Pain

Microglia activation in the spinal cord play a major role in the pathogenesis of neuropathic pain. The p38 mitogen-activated protein kinase (MAPK) regulates microglia activation. Previously, 2',3'-dideoxycytidine (ddC), a nucleoside reverse transcriptase inhibitor (NRTI), was found to induce mechanical allodynia and microglia activation in the spinal cords of male and female mice. In this study, we investigated the role of spinal microglia and p38 MAPK signaling in the development of mechanical allodynia using immunofluorescence staining and treatment with microglia and p38 MAPK inhibitors in both sexes. Male and female mice (BALB/c strain) treated intraperitoneally once daily with ddC 25 mg/kg for five consecutive days developed mechanical allodynia, assessed using the dynamic plantar aesthesiometer. Treatment with ddC increased microglia markers CD11b and ionized calcium-binding adapter molecule 1 (Iba1) staining intensity in male mice, while only CD11b was increased in female mice. Both sexes had increased phosphorylated p38 MAPK staining intensity. The administration of minocycline, an inhibitor of microglia activation, and adezmapimod, a selective p38 MAPK inhibitor, suppressed mechanical allodynia in both sexes at day 7 after ddC treatment. Therefore, microglia activation and p38 MAPK signaling are important for the development of antiretroviral drug-induced mechanical allodynia.

Ovarian vein surgical ablation versus endovascular technique for treatment of pelvic vein incompetence

OBJECTIVE

Chronic pelvic pain in women is a disorder brought on by pelvic vein incompetence (PVI). In this prospective, randomized study, the effects of percutaneous coil embolization and surgical ovarian vein ligation and division combined with retrograde sclerotherapy were compared with regard to ovarian vein occlusion, improvement of pelvic congestion symptoms, and their influence on estradiol level after intervention.

METHODS

A total of 50 patients with PVI were enrolled, with a mean age of 31.9 ± 4.7 years and a pain score of 9 (range, 0-10; from 0 [no pain] to 10 [the highest level of pain]). Both percutaneous coil embolization of ovarian veins (endovascular group) and surgical ovarian vein ablation with retrograde sclerotherapy were offered to the patients at random.

RESULTS

In the open group, the pain level decreased to 2, whereas in the endovascular group, it decreased to 1 (range, 0-10). Estradiol levels were 224 (range, 9-612) in the open group and 478 (range, 18-613) in the endovascular group before the intervention, with no significant change (P = .1120). After 1 week of intervention, estradiol levels in the open group were 89 (range, 18-243) and 124 (range, 22-298) in the endovascular group, respectively, with statistical insignificance (P = .225). After 1 month of intervention, the endovascular group's estradiol level was 101 (range, 20-196) and the open group's was 89 (range, 15-190) (P = .382). After 3 months of intervention, the open group's estradiol level was 78 (range, 12-132) and the endovascular group's was 65 (range, 18-110) (P = .045).

CONCLUSIONS

In addressing PVI, both methods seemed to have promising results. Nevertheless, endovascular management was more effective at decreasing estrogen levels and relieving discomfort. Three months should be the time at which estradiol levels are measured, because this is when they are at their lowest. In both the open and endovascular groups as well as in the pooled data, there was a significant association between estradiol level from before the intervention and improvement in pain scores (P = .005). Because it was linked to a lower pain score, the high preoperative estradiol level can be used to predict postintervention improvement.

Formalin-evoked pain triggers sex-specific behavior and spinal immune response

Mounting evidence shows sex-related differences in the experience of pain with women suffering more from chronic pain than men. Yet, our understanding of the biological basis underlying those differences remains incomplete. Using an adapted model of formalin-induced chemical/inflammatory pain, we report here that in contrast to male mice, females distinctly display two types of nocifensive responses to formalin, distinguishable by the duration of the interphase. Females in proestrus and in metestrus exhibited respectively a short-lasting and a long-lasting interphase, underscoring the influence of the estrus cycle on the duration of the interphase, rather than the transcriptional content of the dorsal horn of the spinal cord (DHSC). Additionally, deep RNA-sequencing of DHSC showed that formalin-evoked pain was accompanied by a male-preponderant enrichment in genes associated with the immune modulation of pain, revealing an unanticipated contribution of neutrophils. Taking advantage of the male-enriched transcript encoding the neutrophil associated protein Lipocalin 2 (Lcn2) and using flow cytometry, we confirmed that formalin triggered the recruitment of LCN2-expressing neutrophils in the pia mater of spinal meninges, preferentially in males. Our data consolidate the contribution of female estrus cycle to pain perception and provide evidence supporting a sex-specific immune regulation of formalin-evoked pain.

Temple cooling increases parasympathetic activity and decreases pressure pain on the hand

BACKGROUND

Applying an ice cube to the temple (the conditioning stimulus) inhibits electrically evoked pain in the forearm. The present study aimed to determine whether temple cooling also inhibits pressure- and heat-pain test stimuli in the upper limb and, if so, to investigate the intra-session test-retest reliability of this response. Additional aims were to establish whether pain inhibition evoked by temple cooling was associated with parasympathetic activity; and to explore sex differences in response.

METHODS

The sample consisted of 40 healthy adults (24 females). Heart rate was recorded continuously throughout the session. An ice cube (3 × 4 cm contact area) was applied for 1 min to the temple on the dominant side. Before and immediately afterwards, the pressure pain threshold was measured from the dorsal hand and sensitivity to heat (individually adjusted at baseline to elicit moderate pain) was measured from the ventral forearm. The procedures were repeated 15 min later.

RESULTS

Temple cooling inhibited pressure pain on the hand but not heat pain on the forearm. However, test-retest reliability of pressure pain inhibition was poor. Heart rate decreased during temple cooling, consistent with a "diving" reflex. Males had stronger pressure pain inhibition, lower heart rate and higher overall autonomic activity than females. However, cardiac parasympathetic activation during temple cooling was comparable in both sexes and was unrelated to pain inhibition.

CONCLUSIONS

These findings indicate that temple cooling evokes pain inhibition that is stronger in males than in females. Cardiac parasympathetic activity does not appear to mediate this response.

SIGNIFICANCE

The conditioning stimulus in the conditioned pain modulation paradigm is often applied to the upper or lower limbs. This may confound pain-inhibitory effects in people with peripheral neuropathy who typically have enhanced or diminished sensation in the extremities. Applying an ice cube at the temple area induces pain-inhibitory effects on the upper limb after the ice is removed. Future research examining pain modulation in people with peripheral neuropathy may consider adopting temple cooling as the conditioning stimulus.

[Impact of adapted physical activity on joint pain induced under adjuvant hormone therapy for breast cancer: A review of the literature]

Hormone therapy provides an excellent survival rate after cancer but has many side effects, including joint pain in one out of two women. This leads about 13 % of women to stop their treatment within the first 6 months, impacting on its effectiveness, survival and the risk of recurrence. In order to better manage pain and quality of life, physical activity is highly recommended. In this context, the present review proposes a state of the art on the effects of adapted physical activity, based on the works referenced in PubMed. These studies show that physical activity has proved its worth in the primary prevention of cancer and is being evaluated in secondary prevention, particularly in the reduction of adverse effects. Overall, there is a reduction in joint pain, an improvement in quality of life and fatigue. Physical activity also plays a role in tertiary prevention. Paradoxically, oncologists and educators often note a reduction in the practice of physical activity due to fear of the onset of pain. It seems necessary to reinforce communication with patients and health professionals and to recommend the practice of physical activity in an appropriate setting.

High Blood Glucose and Excess Body fat Enhance Pain Sensitivity and Weaken Pain Inhibition in Healthy Adults: A Single-blind Cross-over Randomized Controlled Trial

To investigate links between blood glucose, body fat mass and pain, the effects of acute hyperglycaemia on pain sensitivity and pain inhibition were examined in healthy adults with normal (n = 24) or excess body fat (n = 20) determined by dual-energy X-ray absorptiometry. Effects of hyperglycaemia on heart rate variability and reactive hyperaemia were also explored. For the overall sample, ingesting 75-g glucose enhanced pain sensitivity during 1-minute cold-water immersion of both feet (conditioning stimulus) and weakened the pain inhibitory effect of cold water on pressure pain thresholds (test stimulus). Exploratory subgroup analyses not adjusted for multiple comparisons suggested that this effect was limited to people with excess fat mass. In addition, acute hyperglycaemia suppressed resting heart rate variability only in people with excess fat mass. Furthermore, regardless of blood glucose levels, people with excess fat mass had weaker pain inhibition for pinprick after cold water and reported more pain during 5-minutes of static blood flow occlusion. Neither high blood glucose nor excess body fat affected pinprick-temporal summation of pain or reactive hyperaemia. Together, these findings suggest that hyperglycaemia and excess fat mass interfere with pain processing and autonomic function. PERSPECTIVE: Ingesting 75-g glucose (equivalent to approximately 2 standard cans of soft drink) interfered with pain-processing and autonomic function, particularly in people with excess body fat mass. As both hyperglycaemia and overweight are risk factors for diabetes, whether these are sources of pain in people with diabetes should be further explored.

Psychometric evaluation of the Depression Anxiety Stress Scale 8 among women with chronic non-cancer pelvic pain

Psychiatric comorbidity and abusive experiences in chronic pelvic pain (CPP) conditions may prolong disease course. This study investigated the psychometrics of the Depression Anxiety Stress Scale 8 (DASS-8) among women with CPP (N = 214, mean age = 33.3 ± 12.4 years). The DASS-8 expressed excellent fit, invariance across age groups and menopausal status, good know-group validity (differentiating women with psychiatric comorbidity from those without comorbidity: U = 2018.0, p = 0.001), discriminant validity (HTMT ratios < 0.85), excellent reliability (alpha = 0.90), adequate predictive and convergent validity indicated by strong correlation with the DASS-21 (r = 0.94) and high values of item-total correlations (r = 0.884 to 0.893). In two-step cluster analysis, the DASS-8 classified women into low- and high-distress clusters (n = 141 and 73), with significantly higher levels of distress, pain severity and duration, and physical symptoms in cluster 2. The DASS-8 positively correlated with pain severity/duration, subjective symptoms of depression/anxiety, experiences of sexual assault, fatigue, headache severity, and collateral physical symptoms (e.g., dizziness, bloating, fatigue etc.) at the same level expressed by the parent scale and the DASS-12, or even greater. Accordingly, distress may represent a target for early identification of psychiatric comorbidity, CPP severity, experiences of sexual assault, and collateral physical complaints. Therefore, the DASS-8 is a useful brief measure, which may detect mental distress symptoms among women with CPP.

Myofascial Pain Syndrome in Women with Primary Dysmenorrhea: A Case-Control Study

There is limited information on myofascial trigger points (MTrPs) and specific symptoms of chronic pelvic pain and, more specifically, dysmenorrhea. The objective of this study was to determine whether patients suffering from primary dysmenorrhea present alterations in mechanosensitivity and pain patterns, and greater presence of MTrPs in the abdominal and pelvic floor muscles. A case-control study was carried out with a total sample of 84 participants distributed based on primary dysmenorrhea and contraceptive treatment. The sample was divided into four groups each comprising 21 women. Data on pain, quality of life, and productivity and work absenteeism were collected; three assessments were made in different phases of the menstrual cycle, to report data on pressure pain threshold, MTrP presence, and referred pain areas. One-way ANOVA tests showed statistically significant differences (p < 0.01) between the groups, for the Physical Health domain and the total score of the SF-12 questionnaire, and for all the domains of the McGill questionnaire; but no significant differences were found in the data from the WPAI-GH questionnaire. Statistically significant data (p < 0.01) were found for mechanosensitivity in the abdominal area and limbs, but not for the lumbar assessment, within the group, with very few significant intergroup differences. The frequency of active MTrPs is higher in the groups of women with primary dysmenorrhea and during the menstrual phase, with the prevalence of myofascial trigger points of the iliococcygeus muscle being especially high in all examination groups (>50%) and higher than 70% in women with primary dysmenorrhea, in the menstrual phase, and the internal obturator muscle (100%) in the menstrual phase. Referred pain areas of the pelvic floor muscles increase in women with primary dysmenorrhea.

The association between age at menarche and chronic pain outcomes in women: the Tromsø Study, 2007 to 2016

ABSTRACT

Sex differences in chronic pain are well established with documented predominance in women. This study assessed relationships between age at menarche and chronic pain, site-specific chronic pain, pain characteristics, and chronic widespread pain (CWP). We used data from the Tromsø Study conducted in 2007 to 2008 and 2015 to 2016 (Tromsø 6 and Tromsø 7 waves) including participants aged 30 to 99 years. The associations between age at menarche and chronic pain were examined in Tromsø 6 (n = 6449), Tromsø 7 (n = 5681), and the combination of Tromsø 6 and Tromsø 7 (n = 12,130). Tromsø 7 data were used further to examine the associations between age at menarche and site-specific chronic pain, 4 pain characteristics (pain duration, pain intensity, episode duration, and episode frequency), and CWP. All analyses were adjusted for body mass index, age, and economic status of the household in childhood. Lower age at menarche was associated with an increased risk of chronic pain in all 3 samples (risk ratio for each year delay in menarche 0.98, 95% CI [0.97 to 0.99] across samples). Risk differences were -0.014, CI 95% (-0.02 to -0.005) in Tromsø 6, -0.011, CI 95% (-0.02 to -0.02) in Tromsø 7, and -0.012, CI 95% (-0.02 to -0.01) in the combined sample. Age at menarche was significantly associated with chronic pain in the neck, abdomen, and both arms, and CWP. Of the 4 pain characteristics, pain duration was statistically significant. We conclude that early menarche is an independent risk factor for pain across a broad spectrum of pain outcomes.

Hypohydration but not Menstrual Phase Influences Pain Perception in Healthy Women

Chronic pain is a pervasive health problem and is associated with tremendous socioeconomic costs. However, current pain treatments are often ineffective due, in part, to the multi-factorial nature of pain. Mild hypohydration was shown to increase experimental pain sensitivity in men, but whether this also occurs in women has not been examined. Fluctuations in ovarian hormones (i.e., 17ß-oestradiol and progesterone) throughout the menstrual cycle may influence a woman's pain sensitivity, as well as hydration levels, suggesting possible interactions between hypohydration and menstrual phase on pain. We investigated the effects of mild hypohydration (HYPO, 24 hr of fluid restriction) on ischaemic pain sensitivity in 14 eumenorrheic women during the early follicular (EF) and mid-luteal (ML) phases of their menstrual cycle. We also examined whether acute water ingestion could reverse the negative effects of hypohydration. Elevated serum osmolality, plasma copeptin, and urine specific gravity indicated mild hypohydration. Compared to euhydration, HYPO reduced pain tolerance (by 34 ± 46 s; P = 0.02, ηp2 = 0.37) and increased ratings of pain intensity (by 0.7 ± 0.7 cm; P = 0.004; ηp2 = 0.55) and unpleasantness (by 0.7 ± 0.9 cm; P = 0.02; ηp2 = 0.40); these results were not influenced by menstrual phase. Water ingestion reduced thirst perception (Visual Analogue Scale, by 2.3 ± 0.9 cm; P < 0.001, ηp2 = 0.88) but did not reduce pain sensitivity. Therefore, hypohydration increases pain sensitivity in women with no influence of menstrual phase.

Peritraumatic 17β-estradiol levels influence chronic posttraumatic pain outcomes

ABSTRACT

Biologic factors that predict risk for and mediate the development of common outcomes of trauma exposure such as chronic posttraumatic pain (CPTP) are poorly understood. In the current study, we examined whether peritraumatic circulating 17β-estradiol (E2) levels influence CPTP trajectories. 17β-estradiol levels were measured in plasma samples (n = 254) collected in the immediate aftermath of trauma exposure from 3 multiethnic longitudinal cohorts of men and women trauma survivors. Chronic posttraumatic pain severity was evaluated 6 weeks, 6 months, and 1 year after traumatic stress exposure. Repeated measures mixed models were used to test the relationship between peritraumatic E2 levels and prospective CPTP. Secondary analyses in a nested cohort assessed the influence of participant body mass index on the E2-CPTP relationship. In women, a statistically significant inverse relationship between peritraumatic E2 and CPTP was observed (β = -0.280, P = 0.043) such that higher E2 levels predicted lower CPTP severity over time. Secondary analyses identified an E2 * body mass index interaction in men from the motor vehicle collision cohort such that obese men with higher E2 levels were at greater risk of developing CPTP. In nonobese men from the motor vehicle collision cohort and in men from the major thermal burn injury cohort, no statistically significant relationship was identified. In conclusion, peritraumatic circulating E2 levels predict CPTP vulnerability in women trauma survivors. In addition, these data suggest that peritraumatic administration of E2 might improve CPTP outcomes for women; further research is needed to test this possibility.

No Association Between Intrauterine Contraceptive Devices and Musculoskeletal Hip Joint Pain

Purpose

To investigate the association between intrauterine device (IUD) use and hip pain, orthopaedic visits for hip pain, and arthroscopic hip surgery.

Methods

This was a retrospective cohort study of patients aged 18-44 years old using either IUDs or subdermal implants for contraception in a large commercial claims database (MarketScan) from 2012 to 2015. All patients had at least 12 months of continuous enrollment both before and after contraceptive placement. Patients with a history of hip pain or surgery were excluded. The primary outcome was new hip pain. Secondary outcomes included visiting an orthopaedic or sports medicine provider for a hip complaint, intra-articular hip injection, and arthroscopic hip surgery. Outcomes were analyzed with Cox proportional-hazard models.

Results

We identified a total of 242,383 patients, including 216,541 (89.3%) with IUDs and 25,842 (10.7%) with subdermal contraceptive implants. In time-to-event analysis, IUDs (vs implants) were not associated with increased risk of new hip pain diagnoses (hazard ratio [HR] 0.95, 95% confidence interval [CI] 0.87-1.03, P = .21). In contrast, both age (P < .001) and region (P < .001) were associated with increased risk of new hip pain. Similar results were seen for the secondary outcomes, including risk of orthopaedic visits for hip complaints (HR 1.06, 95% CI 0.83-1.35, P = .63), intra-articular injections of the hip (HR 0.94, 95% CI 0.63-1.41, P = .77), and hip arthroscopy procedures (HR 1.13, 95% CI 0.53-2.40, P = .75).

Conclusions

In this study, we found no evidence that IUDs were associated with hip pain or surgery.

Level of Evidence

Level III, retrospective cohort.

The role of gut and genital microbiota and the estrobolome in endometriosis, infertility and chronic pelvic pain

BACKGROUND

Endometriosis is a chronic, burdensome condition that is historically understudied. Consequently, there is a lack of understanding of the etiology of the disease and its associated symptoms, including infertility and chronic pelvic pain (CPP). Endometriosis development is influenced by estrogen metabolism and inflammation, which are modulated by several factors including the microbiome and the estrobolome (the collection of genes encoding estrogen-metabolizing enzymes in the gut microbiome). Therefore, there is increasing interest in understanding the role of microbiota in endometriosis etiology.

OBJECTIVE AND RATIONALE

To date, there is no cure for endometriosis and treatment options often are ineffective. This manuscript will review the potential relationship between the microbiome and endometriosis, infertility and CPP and highlight the available data on the microbiome in relation to endometriosis and its related symptoms. The overarching goal of this manuscript is to inform future microbiome research that will lead to a deeper understanding of the etiology of the disease and possible diagnostic modalities and treatments. The potential impact of the microbiome on estrogen regulation modulated by the estrobolome, as well as inflammation and other endometriosis-promoting mechanisms within the genital tract, will be reviewed. The methodological limitations of microbiome-related studies will be critically assessed to provide improved guidelines for future microbiome and clinical studies.

SEARCH METHODS

PubMed databases were searched using the following keywords: endometriosis AND microbiome, infertility AND microbiome, pelvic pain AND microbiome, IVF (in-vitro fertilization) AND microbiome, endometriosis AND infertility. Clinical and preclinical animal trials that were eligible for review, and related to microbiome and endometriosis, infertility or CPP were included. All available manuscripts were published in 2002-2021.

OUTCOMES

In total, 28 clinical and 6 animal studies were included in the review. In both human and animal studies, bacteria were enriched in endometriosis groups, although there was no clear consensus on specific microbiota compositions that were associated with endometriosis, and no studies included infertility or CPP with endometriosis. However, bacterial vaginosis-associated bacteria and Lactobacillus depletion in the cervicovaginal microbiome were associated with endometriosis and infertility in the majority (23/28) of studies. Interpretation of endometrial studies is limited owing to a variety of methodological factors, discussed in this review. In addition, metadata outlining antibiotic usage, age, race/ethnicity, menopausal status and timing of sample collection in relation to diagnosis of endometriosis was not consistently reported. Animal studies (6/6) support a bidirectional relationship between the gut microbiota and endometriosis onset and progression.

WIDER IMPLICATIONS

There is evidence that a dysbiotic gut or genital microbiota is associated with multiple gynecologic conditions, with mounting data supporting an association between the microbiome and endometriosis and infertility. These microbiomes likely play a role in the gut-brain axis, which further supports a putative association with the spectrum of symptoms associated with endometriosis, including infertility and CPP. Collectively, this review highlights the demand for more rigorous and transparent methodology and controls, consistency across the field, and inclusion of key demographic and clinical characteristics of disease and comparison participants. Rigorous study designs will allow for a better understanding of the potential role of the microbiome in endometriosis etiology and the relationship to other disorders of the female reproductive tract.

Abnormal subgenual anterior cingulate circuitry is unique to women but not men with chronic pain

The subgenual anterior cingulate cortex (sgACC) plays an important role in pain modulation. We previously demonstrated sex differences in sgACC functional connectivity (FC) in healthy individuals. Given that many chronic pain conditions show sex differences in prevalence, here we tested the hypothesis that people with chronic pain exhibit a sex-specific pattern of abnormal sgACC FC. We acquired resting-state functional magnetic resonance imaging data from 156 (82 W: 74 M) healthy participants and 38 (19 W: 19 M) people with chronic low back pain resulting from ankylosing spondylitis, a condition that predominantly affects men. We confirmed that there are sex differences in sgACC FC in our large cohort of healthy adults; women had greater sgACC FC with the precuneus, a key node of the default mode network, and men had greater sgACC FC with the posterior insula and the operculum. Next, we identified an interaction effect between sex and pain status (healthy/chronic pain) for sgACC FC. Within the chronic pain group, women had greater sgACC FC than men to the default mode and sensorimotor networks. Compared to healthy women, women with chronic pain also had greater sgACC FC to the precuneus and lower FC to the hippocampus and frontal regions. No differences in sgACC FC were seen in men with vs without chronic pain. Our findings indicate that abnormal sgACC circuitry is unique to women but not men with ankylosing spondylitis-related chronic pain. These sex differences may impact the benefit of therapeutics that target the sgACC for chronic pain.

Chemogenetic Activation of CX3CR1-Expressing Spinal Microglia Using Gq-DREADD Elicits Mechanical Allodynia in Male Mice

It is important to investigate the sex-dependent roles of microglia in pain hypersensitivity as reactive microglia within the spinal dorsal horn (DH) have been reported to be pivotal in neuropathic pain induction in male rodents upon nerve injury. Here, we aimed at determining the role of sex differences in the behavioral and functional outcomes of the chemogenetic activation of spinal microglia using Gq-designer receptors exclusively activated by designer drugs (Gq-DREADD) driven by the microglia-specific Cx3cr1 promoter. CAG-LSL-human Gq-coupled M3 muscarinic receptors (hM3Dq)-DREADD mice were crossed with CX3C chemokine receptor 1 (CX3CR1)-Cre mice, and immunohistochemistry images revealed that hM3Dq was selectively expressed on Iba1⁺ microglia, but not on astrocytes and neurons. Intrathecal (i.t.) administration of clozapine-N-oxide (CNO) elicited mechanical allodynia exclusively in male mice. Furthermore, the reactive microglia-dominant molecules that contributed to pain hypersensitivity in CX3CR1-hM3Dq were upregulated in mice of both sexes. The degree of upregulation was greater in male than in female mice. Depletion of spinal microglia using pexidartinib (PLX3397), a colony stimulating factor-1 receptor inhibitor, alleviated the male CX3CR1-hM3Dq mice from pain hypersensitivity and compromised the expression of inflammatory molecules. Thus, the chemogenetic activation of spinal microglia resulted in pain hypersensitivity in male mice, suggesting the sex-dependent molecular aspects of spinal microglia in the regulation of pain.

Prospective Association between Dysmenorrhea and Chronic Pain Development in Community-Dwelling Women

Despite emerging evidence of associations between dysmenorrhea, enhanced pain sensitivity, and functional neuroimaging patterns consistent with chronic pain, it is unknown whether dysmenorrhea is prospectively associated with chronic pain development. Gaining a better understanding of this relationship could inform efforts in prevention of chronic pain. Using data from the national Midlife in the United States cohort, we examined the prospective association between dysmenorrhea and chronic pain development during a 10-year follow-up (starting 10 years after dysmenorrhea was measured) among 874 community-dwelling women aged 25-74 at baseline (when dysmenorrhea was measured). We fit modified Poisson regression models adjusting for sociodemographic, lifestyle and psychosocial factors. Among women who were menstruating at baseline, self-reported dysmenorrhea was associated with a 41% greater (95% confidence interval [CI] = 6%-88%) risk of developing chronic pain. Women with dysmenorrhea also developed chronic pain in more body regions (≥3 regions vs 1-2 regions vs none, odds ratio [OR] = 1.77, 95% CI = 1.18-2.64) and experienced greater pain interference (high-interference vs low-interference vs none, OR = 1.73, 95% CI = 1.15-2.59). Among women who had stopped menstruation at baseline, we did not find evidence of an association between their history of dysmenorrhea and subsequent risk of chronic pain development. Results suggest dysmenorrhea may be a general risk factor for chronic pain development among menstruating women. PERSPECTIVE: This study supports the temporality of dysmenorrhea and chronic pain development in a national female sample. Dysmenorrhea was also associated with developing more widespread and disabling pain among women who were still menstruating. Early management of dysmenorrhea may reduce the development and severity of chronic pain in women, although further research is required to determine whether dysmenorrhea is a causal risk factor or a risk marker of chronic pain.

Estrogen decline is a risk factor for paclitaxel-induced peripheral neuropathy: Clinical evidence supported by a preclinical study

We performed clinical retrospective study in female cancer patients and fundamental experiments in mice, in order to clarify risk factors for paclitaxel-induced peripheral neuropathy (PIPN). In the clinical study, 131 of 189 female outpatients with cancer undergoing paclitaxel-based chemotherapy met inclusion criteria. Breast cancer survivors (n = 40) showed significantly higher overall PIPN (grades 1-4) incidence than non-breast cancer survivors (n = 91). Multivariate sub-analyses of breast cancer survivors showed that 57 years of age or older and endocrine therapy before paclitaxel treatment were significantly associated with severe PIPN (grades 2-4). The age limit was also significantly correlated with overall development of severe PIPN. In the preclinical study, female mice subjected to ovariectomy received repeated administration of paclitaxel, and mechanical nociceptive threshold was assessed by von Frey test. Ovariectomy aggravated PIPN in the mice, an effect prevented by repeated treatment with 17β-estradiol. Repeated administration of thrombomodulin alfa (TMα), known to prevent chemotherapy-induced peripheral neuropathy in rats and mice, also prevented the development of PIPN in the ovariectomized mice. Collectively, breast cancer survivors, particularly with postmenopausal estrogen decline and/or undergoing endocrine therapy, are considered a PIPN-prone subpopulation, and may require non-hormonal pharmacological intervention for PIPN in which TMα may serve as a major candidate.

Migraine Is More Prevalent in Advanced-Stage Endometriosis, Especially When Co-Occuring with Adenomoysis

BACKGROUND

Emerging data suggest a significant association between migraine and endometriosis, however the relationship between migraine and endometriosis severity or adenomyosis is unclear. Our objectives were to explore the relationship between migraine and endometriosis, according to the endometriosis severity and co-exist with adenomyosis or not.

METHODS

This case-control study of 167 endometriosis patients verified by surgery and 190 patients for other benign gynecological conditions (control subjects) was performed from September 2017 and January 2021. There is 49 adenomyosis detected by transvaginal ultrasound or histologic diagnosis among the endometriosis patients. Besides, we also included 41 adenomyosis but without endometriosis patients as a subgroup. All women completed a self-administered headache questionnaire and diagnosed as migraine according to the International Headache Society classification. The severity and stage of endometriosis was evaluated with revised American Society of Reproductive Medicine (rASRM) score. We used logistic regression to estimate the association between the presence of migraine and endometriosis severity while accounting for important confounders, including age, body mass index (BMI) and family history of migraine. We also estimate the risk of adenomyosis alone and adenomyosis with co-occurring endometriosis in migrainous women.

RESULTS

Migraine was significantly more prevalent in endometriosis patients compared with controls (29.9% vs. 12.1%, p<0.05), but the prevalence was similar between isolated adenomyosis patients and controls (9.8% vs.12.1%, p>0.05). For all endometriosis and control participants, migraineurs were 4.6-times (OR=4.6; 95% CI 2.7-8.1) more likely to have severe endometriosis. However, the strength of the association decreased when the analysis examined in moderate stage (OR=3.6, 95% CI 2.1-6.2). The risk of mild and minimal endometriosis was not significant (OR=1.9, 95%CI 0.9-4.0; OR=1.6, 95% CI 0.8-3.4; respectively). When we divided the endometriosis patients according to whether co-occurring with adenomyosis. We found in migrainous women, the risk of endometriosis co-exist with adenomyosis increased, with nearly fivefold greater odds compared with control (OR=5.4;95% CI 3.0-9.5), and nearly two times higher than the risk of endometriosis without co-exist adenomyosis patients (OR=2.2; 95% CI 1.2-3.8).

CONCLUSION

Our study supports the strong association between migraine and endometriosis. We found migrainous women suffer more frequently from sever endometriosis, especially endometriosis with co-occurring adenomyosis. It is advisable to heighten suspicion for patients who presenting with either these conditions in order to optimize therapy.

Effect of different factors on patient perception of surgical discomfort in third molar surgery

The aim of this study was to evaluate patient perception of surgical discomfort in third molar surgery and the association with clinical variables and polymorphisms associated with the FKBP5, SLC6A4, and COMT genes. This cross-sectional observational study was carried out on 196 participants aged between 18 and 64 years at the Federal University of Paraná in 11 months. The intensity of surgical discomfort was assessed using the QCirDental questionnaire. Data on surgical and individual procedures were also cataloged. The oral health related quality of life was assessed by the Oral Health Impact Profile questionnaire (OHIP-14). The DNA sample was obtained from cells of the oral mucosa. Five markers of the FKBP5, SLC6A4, and COMT genes were genotyped. The data were submitted to statistical analysis with a significance level of 5%. Women reported greater intensity of discomfort associated with third molar surgery compared to men (p = 0.001). In the recessive model, the AA genotype of the rs3800373 marker was associated with greater surgical discomfort (p = 0.026). Therefore, women and individuals of the AA genotype for the rs3800373 marker in the FKBP5 gene reported greater surgical discomfort associated with third molar surgery.

Pain Across the Menstrual Cycle: Considerations of Hydration

Chronic pain – pain that persists for more than 3 months – is a global health problem and is associated with tremendous social and economic cost. Yet, current pain treatments are often ineffective, as pain is complex and influenced by numerous factors. Hypohydration was recently shown to increase ratings of pain in men, but studies in this area are limited (n = 3). Moreover, whether hypohydration also affects pain in women has not been examined. In women, changes in the concentrations of reproductive hormones across menstrual phases may affect pain, as well as the regulation of body water. This indicates potential interactions between the menstrual phase and hypohydration on pain, but this hypothesis has yet to be tested. This review examined the literature concerning the effects of the menstrual phase and hypohydration on pain, to explore how these factors may interact to influence pain. Future research investigating the combined effects of hypohydration and menstrual phase on pain is warranted, as the findings could have important implications for the treatment of pain in women, interpretation of previous research and the design of future studies.

Changes in pulp sensitivity across the menstrual cycle in healthy women and women with temporomandibular disorders

BACKGROUND

Menstrual cycle may contribute to experimental pain measures in healthy women and women with chronic pain.

OBJECTIVES

The present study aimed to investigate variation in pulp sensitivity across the menstrual cycle in healthy women and women with temporomandibular disorders (TMD) and to explore the effect of TMD pain and psychosocial variables on the pulp response.

METHODS

This longitudinal study involved 47 regularly menstruating women aged 20-45, 24 healthy and 23 with diagnosed painful TMD. The electric and cold stimuli were performed by electric pulp tester and refrigerant spray, respectively, on mandibular lateral incisors, in five menstrual phases (menstrual, follicular, periovulatory, luteal and premenstrual). Research Diagnostic Criteria for TMD were used to assess TMD, chronic pain, depression and somatisation. Regression analysis was performed to investigate the effect of the predictor variables on the pulp sensitivity.

RESULTS

Significant phase-related differences were observed for pain intensity to cold stimuli. Higher pain sensitivity was reported in menstrual in comparison with luteal phase (P = .019) among healthy women, and in menstrual in comparison with follicular (P = .033), periovulatory (P = .003) and luteal (P = .007) phases in TMD women. No significant differences were recorded for electric stimuli. Regression analysis identified depression as the determinant of cold and electric response in menstrual phase, regardless of age and presence of TMD.

CONCLUSION

Menstrual phase in healthy and TMD women with regular menstrual cycle is characterised with higher pulp sensitivity to cold stimuli. Depressive symptoms independently influence pulp response in this phase.

Dual effects of a gonadotropin-releasing hormone agonist on an adolescent girl with pelvic congestion syndrome and precocious puberty: a case report

Pelvic congestion syndrome (PCS) typically causes chronic non-cyclical abdominal pain with a considerable negative effect on the quality of life of women. However, pediatric cases with PCS are limited and non-invasive therapy for adolescent patients has not been reported. We report here a 13-year-old girl who presented with intermittent abdominal pain since the age of 2 years and her symptoms further deteriorated after breast development at 6 years and 9 months old. PCS and coexistent idiopathic central precocious puberty were finally diagnosed on the basis of tortuous ovarian and pelvic veins, and a pubertal response to a gonadotropin-releasing hormone (GnRH) test without hypothalamic–pituitary lesions. After treatment with the GnRH agonist, the pain score was greatly reduced and there was increased prediction of adult height. This case highlights the occurrence of PCS in adolescents and also indicates the role of non-invasive GnRH agonists in young patients with PCS before surgical intervention.

Sex Hormones, BDNF, Leptin, and TGF-β1 in Females With IBS: A Pilot Investigation

BACKGROUND

Irritable bowel syndrome (IBS) is a chronic gastrointestinal condition predominantly affecting the female sex, and is characterized by brain-gut axis dysregulation. Relevance of hormones along the hypothalamic-pituitary gonadal axis and hypothalamic-pituitary adrenal axis to IBS symptomatology remain unclear, as does the significance of other modulators including brain derived neurotrophic factor (BDNF), leptin, and transforming growth factor βeta 1 (TGF-β1).

METHODS

Females with IBS were compared with female healthy controls (HC) on age, race, hormonal contraceptive use, body mass index, adrenocorticotropic hormone, cortisol, estradiol, follicular stimulating hormone, luteinizing hormone, progesterone, total cholesterol, Center for Epidemiological Studies Depression Scale (CES-D) and Perceived Stress Scale (PSS). BDNF, leptin, and TGF-β1 were quantified using enzyme-linked immunosorbent assay. Descriptive statistics, non-parametric techniques, and regression analyses were performed.

RESULTS

Participants with IBS (n = 12) displayed higher estradiol (p = .027) than did HC (n = 21). Direction of associations among study variables often differed between groups: BDNF and progesterone in HC (r_s = .623) and in IBS (r_s = -.723). The relationship between log (CES-D) and log (estradiol) varied by IBS status (interaction term p = 0.019).

DISCUSSION

Elevated estradiol in participants with IBS, and differential patterns of biological and psychological indices between groups, encourages further inquiry on the relevance of sex hormones, BDNF, leptin, and TGF-β1 to symptoms of IBS. Future research endeavors should conduct longitudinal quantification of sex hormones with subjective symptom assessment to facilitate insight on the pathophysiology and female sex bias in IBS.

Menstrual migraine: what it is and does it matter?

The diagnostic criteria of menstrual migraine (MM), migraine related to menstruation and pure menstrual migraine, are placed in the appendix of the International Classification of Headache Disorders and are still primarily considered as research criteria that need validation. Although there is a great wealth of knowledge about the neurobiological processes underlying MM and its symptoms, the mechanisms by which an attack starts during the menstrual cycle remain baffling, and the disease is still undertreated. In this narrative review, we aim to summarize recent data on pathophysiology, epidemiology, burden of disease and treatment of MM. The vast majority of the literature focuses on the relationship between MM and hormonal factors. The role of falling in estrogen levels is believed to increase the susceptibility of blood vessels to prostaglandins, which have been implicated in neurogenic inflammation. Moreover, fluctuations of ovarian steroid hormone levels modulate calcitonin gene-related peptide in the trigeminovascular system. In addition, it has been observed that gonadal hormones modulate cortical spreading depression susceptibility in animal models. Sex hormone influences on MM affect not only the frequency and severity of headache attack but also its treatment. Understanding the mechanisms that contribute to neuroendocrine vulnerability in some women and some menstrual cycles may yield possible marker of the disease opening treatment options specifically targeting MM. An increased interest for future research on the subject will further elucidate how to manage this debilitating type of migraine.

Migraine in relation with endometriosis phenotypes: Results from a French case-control study

BACKGROUND

Studies have shown a significant association between migraine and endometriosis, but no study has explored the relationship between migraine and endometriosis phenotypes: Superficial peritoneal endometriosis, ovarian endometrioma, and deep infiltrating endometriosis.

METHODS

We conducted a case-control study using data collected from 314 women aged 18 to 42 years who had undergone surgery for benign gynecological conditions between January 2013 and December 2015. All women completed a self-administered headache questionnaire according to the IHS classification. Cases (n = 182) are women with histologically proven endometriosis and controls are women (n = 132) without endometriosis. Occurrence of migraine was studied according to endometriosis phenotypes.

RESULTS

Migraine prevalence in cases was significantly higher compared with controls (35.2% vs. 17.4%, p = 0.003). The risk of endometriosis was significantly higher in migrainous women (OR = 2.62; 95% CI = 1.43-4.79). When we take into account endometriosis phenotypes, the risk of ovarian endometrioma and deep infiltrating endometriosis were significant (OR = 2.78; 95% CI = 1.11-6.98 and OR = 2.51; 95% CI = 1.25-5.07, respectively). In women with endometriosis, the intensity of chronic non-cyclical pelvic pain was significantly greater for those with migraine (visual analogic scale (VAS) = 3.6 ± 2.9) compared with the women without headache (VAS = 2.3 ± 2.8, p = 0.0065).

CONCLUSION

Our study shows a significant association between migraine and endometriosis. In clinical practice, women of reproductive age who suffer from migraine should be screened for endometriosis criteria in order to optimise the medical and therapeutic care of this condition.

Sex Differences in Opioid Use in Patients With Symptomatic Lumbar Stenosis or Spondylolisthesis Undergoing Lumbar Decompression and Fusion

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To investigate sex differences in opioid use after lumbar decompression and fusion surgery for patients with symptomatic lumbar stenosis or spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Recent studies have demonstrated higher prevalence of chronic pain states and greater pain sensitivity among women compared with men. Furthermore, differences in responsivity to pharmacological and non-pharmacological treatments have been observed. Whether sex differences in perioperative opioid use exists in patients undergoing lumbar fusion for symptomatic stenosis or spondylolisthesis remains unknown.

METHODS

An insurance database, including private/commercially insured and Medicare Advantage beneficiaries, was queried for patients with symptomatic lumbar stenosis or spondylolisthesis undergoing index 1,2, or 3-level index lumbar decompression and fusion procedures between 2007 and 2016. Records were searchable by International Classification of diseases diagnosis and procedure codes, and generic drug codes specific to Humana. Opioid use 6-months prior to through 2-years after index surgery was assessed. The primary outcome was sex differences in opioid use after index lumbar surgery. The secondary outcome was independent predictors of prolonged opioid use after lumbar fusion.

RESULTS

Of the 13,257 participants (females: 7871, 59.8%), 58.4% of women used opioids compared with 56.9% of men prior to index surgery. At 1-year after surgery, continuous opioid use was observed in 67.1% of women compared with 64.2% of men (P < 0.001). Within 2-years postoperatively, opioid use was observed in 83.1% of women versus 82.5% men. In a multivariate logistic regression analysis, female sex (odds ration [OR] 1.14, 95% confidence interval [CI]: 1.058-1.237), obesity (OR 1.10, 95% CI: 1.004-1.212), and preoperative narcotic use (OR 3.43, 95% CI: 3.179-3.708) was independently associated with prolonged (>1 yr) opioid use after index surgery.

CONCLUSION

We observed a higher prevalence of chronic opioid use among women following lumbar fusion surgery. Female sex was independently associated with prolonged opioid use after index surgery.

LEVEL OF EVIDENCE

3.

Psychological distress and self-rated health status in reproductive aged women with pain: findings from a national, cross-sectional survey

Background

Pain impacts upon psychological wellbeing. In pregnant and postpartum women psychological distress may negatively affect the mother-infant relationship and lead to adverse infant development. Yet, co-occurrence of pain with psychological distress in women of reproductive age has not been investigated. Therefore, this study aimed to: 1) assess prevalence of psychological distress in reproductive aged women by pain severity; and 2) examine the self-rated health status of reproductive aged women with and without pain.

Method

Data for women aged 18–49 years were obtained from the 2011–12 Australian Bureau of Statistics National Health Survey. Sample data were weighted to give population estimates. Recent pain severity, self-rated health and psychological distress were analysed for pregnant, breastfeeding and non-pregnant/non-breastfeeding women.

Results

Moderate-to-very severe pain was reported by 17.6% of pregnant (sample n = 165, weighted N = 191,856), 25.9% of breastfeeding (sample n = 210, weighted N = 234,601) and 23.9% of non-pregnant/non-breastfeeding women (sample n = 4005, weighted N = 4,607,140). Psychological distress was associated with pain in non-pregnant/non-breastfeeding women (p < 0.001). High-to-very high distress was seen in 26.4% (95% CI, 23.2–29.6) of NP/NBF, 8.1% (95% CI, 0–17.2) of breastfeeding and 7.3% (95% CI, 0–18.0) of pregnant women with moderate-to-very severe pain. Self-rated health status was associated with pain severity in pregnant (p = 0.001) and non-pregnant/non-breastfeeding (p < 0.001) women.

Conclusion

Given the strong association between psychological distress and pain in non-pregnant/non-breastfeeding women, and the relatively common occurrence of moderate-to-very severe pain in both pregnant and breastfeeding women, assessment of psychological distress levels in all women of reproductive age who report experiencing moderate-to-very severe levels of pain may be of benefit.

Characterizing chronic pain and alcohol use trajectory among treatment-seeking alcoholics

Accumulating evidence indicates pain may be an important risk factor for development of alcohol use disorder (AUD) and risk of relapse for people recovering from AUD. This study was conducted to characterize the prevalence and severity of significant recurrent pain and various chronic pain conditions in treatment-seeking alcoholics. In addition, we sought to examine associations between alcohol use trajectory and pain presence/severity. Four hundred fifty-one treatment-seeking alcoholics were recruited for this study. Participants completed a battery of assessments, including measures of demographics, affect, alcohol and other drug use, presence/absence of significant recurrent pain, recent pain severity, and chronic pain type. Analyses indicated significant recurrent pain was highly prevalent in the study sample (53.66%), and was significantly more common among women (62.57%) than men (47.35%; p = 0.001). Typical drinking prior to treatment did not differ by pain status, but participants with pain were more likely to report current opioid use. Individuals with pain reported greater depression and anxiety than those without (p < 0.0008), and pain tended to be more severe among women than men (p = 0.035). Both men and women with pain indicated that pain had affected their substance use. In addition, both later age of first treatment and longer transition time from alcohol dependence to treatment were associated with greater pain severity, especially among men. These data suggest chronic pain is highly prevalent among treatment-seeking alcoholics, especially women, and that delays to first treatment are associated with pain presence and intensity. These results highlight the importance of effective pain management for the subset of treatment seekers with pain.

Sex Differences in Estradiol Secretion by Trigeminal Brainstem Neurons

Estrogen status is a significant risk factor in the development of temporomandibular joint disorders (TMD). Classically, estrogen status is thought to derive mainly from ovarian sources; however, it is well known that estradiol (E2) also is synthesized by neurons in the brain. This study tested the hypothesis that E2 is produced by neurons in trigeminal subnucleus caudalis (Vc), the principal site of termination for sensory afferents that supply the temporomandibular joint (TMJ), to modify evoked responses in a model of TMJ nociception in male and female rats. Intra-TMJ injection of the small fiber excitant, allyl isothiocyanate (AIC), increased the levels of E2 collected from microdialysis probes sites at Vc of ovariectomized (OvX) female rats, ipsilateral to the stimulus, whereas males displayed no change. Dialysate levels of E2 collected from probe sites in the contralateral Vc or cerebellum in OvX rats were not affected by TMJ stimulation. Reverse dialysis of anastrozole, an aromatase (ARO) inhibitor, via the probe reduced perfusate levels of E2 in Vc. Systemic administration of letrozole, a non-steroid ARO inhibitor, for 4 days prevented TMJ-evoked increases in masseter muscle electromyography (MMemg) activity. ARO-positive neurons were distributed mainly in superficial laminae (I-III) at Vc and cell counts revealed no significant difference between OvX and male rats. Intra-TMJ injection of AIC revealed similar numbers of ARO/Fos dual-labeled neurons in OvX and male rats. By contrast, the percentage of ARO neurons co-labeled for glutamic acid decarboxylase (GAD), the biosynthetic enzyme for GABA, was greater in OvX (35%) than male rats (14%). Few ARO-positive neurons were co-labeled for estrogen receptor alpha. These data indicate that E2 is secreted continuously by Vc neurons and that acute stimulation of TMJ nociceptors evokes further secretion in a sex-dependent manner. Reduced TMJ-evoked MMemg activity after ARO inhibition suggests that locally produced E2 by Vc neurons acts via paracrine mechanisms to modify TMJ nociception in female rats.

Exploiting endogenous opioids: Lessons learned from endomorphin 2 in the female rat

Effective management of chronic pain is demanded by ethical as well as medical considerations. Although opioid analgesics remain among the most effective pharmacotherapies for ameliorating many types of pain, their use is clouded by concerns regarding their addictive properties, underscored by the current epidemic of prescription opioid abuse and attendant deaths. Medicinal harnessing of endogenous opioid antinociception could provide a strategy for continuing to take advantage of the powerful antinociceptive properties of opioids while avoiding their abuse potential. Based on our studies of endogenous mechanism that suppress and facilitate spinal endomorphin 2 antinociception over the rat reproductive cycle, we identified multiple signaling molecules that could serve as targets for activating endogenous opioid analgesia for chronic pain management in women. Our findings emphasize the need for a precision medicine approach that includes stage of menstrual cycle as an important determinant of drug targets for (activating/harnessing) endogenous opioid antinociceptive systems/ capabilities. Utilization of drugs that harness endogenous opioid antinociception in accordance with varying physiological states represents a novel approach for effective pain management.

The Expression of Transcription Factors Mecp2 and CREB Is Modulated in Inflammatory Pelvic Pain

Early activation of transcription factors is one of the epigenetic mechanisms contributing to the induction and maintenance of chronic pain states. Previous studies identified the changes in a number of nociception-related genes, such as calcitonin gene-related peptide (CGRP), substance P (SP), and brain-derived neurotropic factor (BDNF) in the pelvic organs after transient colonic inflammation. The gene and protein expression of these neuropeptides could be modulated by transcription factors Methyl-CpG-binding protein 2 (Mecp2) and cAMP response element-binding protein (CREB). In this study, we aimed to evaluate time-dependent changes in the expression levels of Mecp2 and CREB in the lumbosacral (LS) spinal cord and sensory ganglia after inflammation-induced pelvic pain in rat. Adult Sprague-Dawley rats were treated with 2,4,6-trinitrobenzenesulfonic acid (TNBS) to induce transient colonic inflammation. LS (L6-S2) spinal cord segments and respective dorsal root ganglias (DRGs) were isolated from control and experimental animals at 1, 2, 6, 24 h and 3 days post-TNBS treatment. Immunohistochemical (IHC) labeling and Western blotting experiments were performed to assess the expression of Mecp2, CREB and their phosphorylated forms. Total Mecp2 expression, but not phosphorylated p-Mecp2 (pS421Mecp2) expression was detected in the cells of the spinal dorsal horn under control conditions. Colonic inflammation triggered a significant decrease in the number of Mecp2-expressing neurons in parallel with elevated numbers of pS421Mecp2-expressing cells at 2 h and 6 h post-TNBS. The majority of Mecp2-positive cells (80 ± 6%) co-expressed CREB. TNBS treatment caused a transient up-regulation of CREB-expressing cells at 1 h post-TNBS only. The number of cells expressing phosphorylated CREB (pS133CREB) did not change at 1 h and 2 h post-TNBS, but was down-regulated by three folds at 6 h post-TNBS. Analysis of DRG sections revealed that the number of Mecp2-positive neurons was up-regulated by TNBS treatment, reaching three-fold increase at 2 h post-TNBS, and eight-fold increase at 6 h post-TNBS (p ≤ 0.05 to control). These data showed early changes in Mecp2 and CREB expression in the dorsal horn of the spinal cord and sensory ganglia after colonic inflammation, suggesting a possible contribution Mecp2 and CREB signaling in the development of visceral hyperalgesia and pelvic pain following peripheral inflammation.

Pharmacological Modulation of Endogenous Opioid Activity to Attenuate Neuropathic Pain in Rats

We showed previously that spinal metabotropic glutamate receptor 1 (mGluR₁) signaling suppresses or facilitates (depending on the stage of estrous cycle) analgesic responsiveness to intrathecal endomorphin 2, a highly mu-opioid receptor-selective endogenous opioid. Spinal endomorphin 2 antinociception is suppressed during diestrus by mGluR₁ when it is activated by membrane estrogen receptor alpha (mERα) and is facilitated during proestrus when mGluR₁ is activated by glutamate. In the current study, we tested the hypothesis that in female rats subjected to spinal nerve ligation (SNL), the inhibition of spinal estrogen synthesis or blockade of spinal mERα/mGluR₁ would be antiallodynic during diestrus, whereas during proestrus, mGluR₁ blockade would worsen the mechanical allodynia. As postulated, following SNL, aromatase inhibition or mERα/mGluR₁ blockade during diestrus markedly lessened the mechanical allodynia. This was observed only on the paw ipsilateral to SNL and was eliminated by naloxone, implicating endogenous opioid mediation. In contrast, during proestrus, mGluR₁ blockade worsened the SNL-induced mechanical allodynia of the ipsilateral paw. Findings suggest menstrual cycle stage-specific drug targets for and the putative clinical utility of harnessing endogenous opioids for chronic pain management in women, as well as the value of, if not the necessity for, considering menstrual cycle stage in clinical trials thereof. PERSPECTIVE: Intrathecal treatments that enhance spinal endomorphin 2 analgesic responsiveness under basal conditions lessen mechanical allodynia in a chronic pain model. Findings provide a foundation for developing drugs that harness endogenous opioid antinociception for chronic pain relief, lessening the need for exogenous opioids and thus prescription opioid abuse.

Gender-specific associations between fat mass, metabolic syndrome and musculoskeletal pain in community residents: A three-year longitudinal study

Increase in fat mass is correlated with musculoskeletal pain. The aim of this study was to examine the relationship between fat mass and the musculoskeletal pain prospectively in Korean community residents. In the Korean Health and Genome Study, participants (mean age 60.2 years, 56.2% women) completed pain questionnaires and underwent dual x-ray absorptiometry to calculate body composition. Three-year follow-up data on pain was available for 1,325 participants. Pain was categorized according to number of pain regions. At three years of follow-up, participants were classified as follows: 1) no pain both at baseline and at three years (no pain), 2) any pain (one, two or more, or widespread regions) at baseline and no pain at three years (transient pain), 3) no pain at baseline and any pain at three years (new pain) 4) any pain both at baseline and at 3 years (persistent pain). 1) and 2) were grouped as no/transient pain group (no pain) and 3) and 4) as new/persistent pain group (pain). Female gender and obesity were two significant factors associated with the persistence or development of pain. Total fat mass and fat:muscle mass ratio were associated with pain among female participants only, and the odds ratios for pain were significantly increased in female participants in the highest quartile of total fat mass and fat muscle ratio after adjustment. In conclusion, both female gender and obesity were two significant factors associated with pain. Fat mass parameters and pain were significantly associated only among females.

Effect of Pain Neuroscience Education Combined With Cognition-Targeted Motor Control Training on Chronic Spinal Pain: A Randomized Clinical Trial

Importance

Effective treatments for chronic spinal pain are essential to reduce the related high personal and socioeconomic costs.

Objective

To compare pain neuroscience education combined with cognition-targeted motor control training with current best-evidence physiotherapy for reducing pain and improving functionality, gray matter morphologic features, and pain cognitions in individuals with chronic spinal pain.

Design, Setting, and Participants

Multicenter randomized clinical trial conducted from January 1, 2014, to January 30, 2017, among 120 patients with chronic nonspecific spinal pain in 2 outpatient hospitals with follow-up at 3, 6, and 12 months.

Interventions

Participants were randomized into an experimental group (combined pain neuroscience education and cognition-targeted motor control training) and a control group (combining education on back and neck pain and general exercise therapy).

Main Outcomes and Measures

Primary outcomes were pain (pressure pain thresholds, numeric rating scale, and central sensitization inventory) and function (pain disability index and mental health and physical health).

Results

There were 22 men and 38 women in the experimental group (mean [SD] age, 39.9 [12.0] years) and 25 men and 35 women in the control group (mean [SD] age, 40.5 [12.9] years). Participants in the experimental group experienced reduced pain (small to medium effect sizes): higher pressure pain thresholds at primary test site at 3 months (estimated marginal [EM] mean, 0.971; 95% CI, -0.028 to 1.970) and reduced central sensitization inventory scores at 6 months (EM mean, -5.684; 95% CI, -10.589 to -0.780) and 12 months (EM mean, -6.053; 95% CI, -10.781 to -1.324). They also experienced improved function (small to medium effect sizes): significant and clinically relevant reduction of disability at 3 months (EM mean, -5.113; 95% CI, -9.994 to -0.232), 6 months (EM mean, -6.351; 95% CI, -11.153 to -1.550), and 12 months (EM mean, -5.779; 95% CI, -10.340 to -1.217); better mental health at 6 months (EM mean, 36.496; 95% CI, 7.998-64.995); and better physical health at 3 months (EM mean, 39.263; 95% CI, 9.644-66.882), 6 months (EM mean, 53.007; 95% CI, 23.805-82.209), and 12 months (EM mean, 32.208; 95% CI, 2.402-62.014).

Conclusions and Relevance

Pain neuroscience education combined with cognition-targeted motor control training appears to be more effective than current best-evidence physiotherapy for improving pain, symptoms of central sensitization, disability, mental and physical functioning, and pain cognitions in individuals with chronic spinal pain. Significant clinical improvements without detectable changes in brain gray matter morphologic features calls into question the relevance of brain gray matter alterations in this population.

Trial Registration

clinicaltrials.gov Identifier: NCT02098005.

Estrogens synthesized and acting within a spinal oligomer suppress spinal endomorphin 2 antinociception: ebb and flow over the rat reproductive cycle

The magnitude of antinociception elicited by intrathecal endomorphin 2 (EM2), an endogenous mu-opioid receptor (MOR) ligand, varies across the rat estrous cycle. We now report that phasic changes in analgesic responsiveness to spinal EM2 result from plastic interactions within a novel membrane-bound oligomer containing estrogen receptors (mERs), aromatase (aka estrogen synthase), metabotropic glutamate receptor 1 (mGluR1), and MOR. During diestrus, spinal mERs, activated by locally synthesized estrogens, act with mGluR1 to suppress spinal EM2/MOR antinociception. The emergence of robust spinal EM2 antinociception during proestrus results from the loss of mER-mGluR1 suppression, a consequence of altered interactions within the oligomer. The chemical pairing of aromatase with mERs within the oligomer containing MOR and mGluR1 allows estrogens to function as intracellular messengers whose synthesis and actions are confined to the same signaling oligomer. This form of estrogenic signaling, which we term "oligocrine," enables discrete, highly compartmentalized estrogen/mER-mGluR1 signaling to regulate MOR-mediated antinociception induced by EM2. Finally, spinal neurons were observed not only to coexpress MOR, mERα, aromatase, and mGluR1 but also be apposed by EM2 varicosities. This suggests that modulation of spinal analgesic responsiveness to exogenous EM2 likely reflects changes in its endogenous analgesic activity. Analogous suppression of spinal EM2 antinociception in women (eg, around menses, comparable with diestrus in rats) as well as the (pathological) inability to transition out of that suppressed state at other menstrual cycle stages could underlie, at least in part, the much greater prevalence and severity of chronic pain in women than men.

Acupuncture for chronic pelvic inflammatory disease: A systematic review protocol

BACKGROUND

Chronic pelvic inflammation disease (PID) is a difficult-to-treat gynecological disorder with complex etiologies. Acupuncture has been applied widely for treating chronic pelvic inflammation or chronic pelvic pain symptoms in China. The aim of this review is to undertake a systematic review to estimate the effectiveness and safety of acupuncture on chronic PID.

METHODS

A literature search will be conducted electronically with date up to October 2018 in MEDLINE, Cochrane Library, EBASE, and CNKI databases, using combination subject terms of chronic pelvic pain (or chronic pelvic inflammation, and chronic pelvic pain symptoms, etc.) and acupuncture related treatment. Also duplicates will be removed. The primary outcomes consisted of improvement rate and pain relief. Secondary outcomes include the recurrence rate and side effects, such as pneumothorax, bleeding, serious discomfort, subcutaneous nodules, and infection. Systematic reviews and databases will be searched for randomized controlled trials on acupuncture for chronic PID with acupuncture treatment will be included. Cochrane RevMan V5.3.5 risk of bias assessment tool will be implemented for risk of bias evaluation, data synthesis, meta-analyses, and subgroup analysis while condition is met. Mean difference (MD), standard mean difference (SMD), and dichotomous data will be used to present continuous outcomes.

RESULTS

This study will generate a comprehensive review of current evidence of acupuncture for chronic pelvic inflammation diseases.

CONCLUSION

The study will provide updated evidence to evaluate the effectiveness and side effects of acupuncture for chronic pelvic inflammation disease.

PROSPERO REGISTRATION NUMBER

CRD42018087950.

Plasticity of Signaling by Spinal Estrogen Receptor α, κ-Opioid Receptor, and Metabotropic Glutamate Receptors over the Rat Reproductive Cycle Regulates Spinal Endomorphin 2 Antinociception: Relevance of Endogenous-Biased Agonism

We previously showed that intrathecal application of endomorphin 2 [EM2; the highly specific endogenous μ-opioid receptor (MOR) ligand] induces antinociception that varies with stage of the rat estrous cycle: minimal during diestrus and prominent during proestrus. Earlier studies, however, did not identify proestrus-activated signaling strategies that enable spinal EM2 antinociception. We now report that in female rats, increased spinal dynorphin release and κ-opioid receptor (KOR) signaling, as well as the emergence of glutamate-activated metabotropic glutamate receptor 1 (mGluR₁) signaling, are critical to the transition from an EM2 nonresponsive state (during diestrus) to an analgesically responsive state (during proestrus). Differential signaling by mGluR₁, depending on its activation by membrane estrogen receptor α (mERα; during diestrus) versus glutamate (during proestrus), concomitant with the ebb and flow of spinal dynorphin/KOR signaling, functions as a switch, preventing or promoting, respectively, spinal EM2 antinociception. Importantly, EM2 and glutamate-containing varicosities appose spinal neurons that express MOR along with mGluRs and mERα, suggesting that signaling mechanisms regulating analgesic effectiveness of intrathecally applied EM2 also pertain to endogenous EM2. Regulation of spinal EM2 antinociception by both the nature of the endogenous mGluR₁ activator (i.e., endogenous biased agonism at mGluR₁) and changes in spinal dynorphin/KOR signaling represent a novel mechanism for modulating analgesic responsiveness to endogenous EM2 (and perhaps other opioids). This points the way for developing noncanonical pharmacological approaches to pain management by harnessing endogenous opioids for pain relief.SIGNIFICANCE STATEMENT The current prescription opioid abuse epidemic underscores the urgency to develop alternative pharmacotherapies for managing pain. We find that the magnitude of spinal endomorphin 2 (EM2) antinociception not only varies with stage of reproductive cycle, but is also differentially regulated during diestrus and proestrus. This finding highlights the need for sex-specific and cycle-specific approaches to pain management. Additionally, our finding that spinal EM2 antinociception in female rats is regulated by both the ebb and flow of spinal dynorphin/κ-opioid receptor signaling over the estrous cycle, as well as the nature of the endogenous mGluR₁ activator, could encourage noncanonical pharmacological approaches to pain management, such as harnessing endogenous opioids for pain relief.