Association of dysmenorrhea with interstitial cystitis/bladder pain syndrome: a case-control study

OPRM1 A118G polymorphism modulating motor pathway for pain adaptability in women with primary dysmenorrhea

Introduction

Primary dysmenorrhea (PDM) is a common condition among women of reproductive age, characterized by menstrual pain in the absence of any organic causes. Previous research has established a link between the A118G polymorphism in the mu-opioid receptor (OPRM1) gene and pain experience in PDM. Specifically, carriers of the G allele have been found to exhibit maladaptive functional connectivity between the descending pain modulatory system and the motor system in young women with PDM. This study aims to explore the potential relationship between the OPRM1 A118G polymorphism and changes in white matter in young women with PDM.

Methods

The study enrolled 43 individuals with PDM, including 13 AA homozygotes and 30 G allele carriers. Diffusion tensor imaging (DTI) scans were performed during both the menstrual and peri-ovulatory phases, and tract-based spatial statistics (TBSS) and probabilistic tractography were used to explore variations in white matter microstructure related to the OPRM1 A118G polymorphism. The short-form McGill Pain Questionnaire (MPQ) was used to access participants' pain experience during the MEN phase.

Results

Two-way ANOVA on TBSS analysis revealed a significant main effect of genotype, with no phase effect or phase-gene interaction detected. Planned contrast analysis showed that during the menstrual phase, G allele carriers had higher fractional anisotropy (FA) and lower radial diffusivity in the corpus callosum and the left corona radiata compared to AA homozygotes. Tractographic analysis indicated the involvement of the left internal capsule, left corticospinal tract, and bilateral medial motor cortex. Additionally, the mean FA of the corpus callosum and the corona radiata was negatively correlated with MPQ scales in AA homozygotes, but this correlation was not observed in G allele carriers. No significant genotype difference was found during the pain-free peri-ovulary phase.

Discussion

OPRM1 A118G polymorphism may influence the connection between structural integrity and dysmenorrheic pain, where the G allele could impede the pain-regulating effects of the A allele. These novel findings shed light on the underlying mechanisms of both adaptive and maladaptive structural neuroplasticity in PDM, depending on the specific OPRM1 polymorphism.

Interstitial cystitis/bladder pain syndrome patient is associated with subsequent increased risks of outpatient visits and hospitalizations: A population-based study

Interstitial cystitis/bladder pain syndrome (IC/BPS) is not only a chronic urinary bladder pain syndrome but is also associated with multifactorial etiology. Our study aimed to test the hypothesis that IC/BPS is associated with subsequent increased risks of outpatient visits and hospitalizations. Using nationwide database, the diagnoses were based on the International Classification Codes (ICD-9-CM) (595.1) of at least three outpatient services during 2002-2008, (n = 27,990) and cystoscopic finding Hunner type and/or glomerulation with pre-audit criteria. All recruited cases monitored for subsequent outpatient visits and hospitalizations for 2 years, including all-cause and specialty-specific departments, were classified according to medical specialty and age group (<40, 40-60, ≥60 years of age). IC/BPS patients have more overall outpatient department (OPD) visits and an overall adjusted incidence rate ratio (IRR) of 1.64. As for specialty, IRRs were higher in psychiatry (2.75), Chinese medicine (2.01), and emergency medicine (2.00), besides urology and gynecology. The IRRs decreased as age advanced (2.01, 1.71, and 1.44, respectively), except for gynecology (2.42, 2.52, and 2.81). A similar phenomenon happens in hospitalization with IRR of 1.69. Due to claim data characteristics, whether ulcer type IC/BPS findings can be deductive to non-ulcer type remains inclusive. Current results indicate the impacts of healthcare burden in broad spectrum about IC/PBS patients. IC/BPS has been suggested to be associated with lower threshold of healthcare visits and some coexisting disease and is comprised of systemic dysregulation, and is beyond the scope of local bladder-urethra disease. Adequate recognition of associated or comorbid factors and possible recommendation or referral for IC/BPS patients can help provide better healthcare quality.

Is primary dysmenorrhea a precursor of future endometriosis development?

Primary dysmenorrhea (PD) is the most common gynecologic disorder during adolescence and it is characterized by crampy lower abdominal pain that occurs during menstruation. Secondary dysmenorrhea, in contrast, has the same clinical features but occurs in women with a disease that could account for their symptoms (endometriosis, adenomyosis, uterine fibroids, pelvic inflammatory disease). Endometriosis is the most common cause of secondary dysmenorrhea and it should be considered in patients with persistent and clinically significant dysmenorrhea despite treatment. It is often diagnosed after a long delay, increasing the likelihood of pain chronicity and fertility problems at a later age. Women who suffer from dysmenorrhea in adolescence have higher risk of endometriosis in future. The open question is if endometriosis was already present at the onset of dysmenorrhea but undiagnosed or if PD favors subsequent development of endometriosis-associated pain. Since PD is associated with higher risk for developing chronic pain state and shares some of the same pain pathways of endometriosis (prostaglandins overproduction, inflammation, peripheral sensitization, central sensitization and abnormal stress responses), a correlation between PD and endometriosis is suggested. To know whether it is a risk factor for the development of endometriosis-associated pain may provide an opportunity for early intervention and prevention. The present review aims to investigate the clinical and pathogenetic features of PD and endometriosis in order to identify a possible association between the two conditions.

Abnormal white matter microstructure along the thalamus fiber pathways in women with primary dysmenorrhea

Primary dysmenorrhea (PDM) is a cyclic menstrual pain in the absence of pelvic anomalies, and women with PDM have an increased sensitivity to pain than the internal and external areas associated with menstrual pain. However, the brain abnormality in the ascending pain pathways in dysmenorrhea remains largely unclear. As the thalamus plays a significant role in transmission of nociceptive input, we examined whether white matter microstructure of the thalamus-related fiber tracts obtained by DTI in women with PDM (n = 47) differs from healthy controls. A novel tractography atlas-based analysis method that detects tract integrity and altered microstructural properties along selected fibers was employed. The fiber bundles of interest contained the thalamus- primary somatosensory cortex (SI), thalamus- dorsal anterior cingulate cortex (dACC)/supplementary motor area (SMA), thalamus-insula, and thalamus-ACC. As compared with controls, abnormal white matter microstructures were found along the thalamus-related white matter fiber tracts. Additionally, the intensity of menstrual pain was significantly associated with diffusion measures of thalamus-SI fiber connections. Our study suggested that the thalamus-related pain processing pathways had altered white matter integrity that persisted beyond the time of menstruation, and the white matter microstructure of the thalamus-SI pathways was closely related to menstrual pain in the intensity by women with PDM.

Association between dysmenorrhea and chronic pain: a systematic review and meta-analysis of population-based studies

OBJECTIVE

The objective of the study was to synthesize the epidemiological findings for the associations between dysmenorrhea, including primary dysmenorrhea and endometriosis-associated dysmenorrhea and any chronic pain conditions, including chronic pelvic pain, and chronic nonpelvic pain.

DATA SOURCES

The data sources included PubMed, Embase, and CINAHL from inception to December 2019.

STUDY ELIGIBILITY CRITERIA

The study criteria included observational population-based studies in which the relationship between dysmenorrhea and the presence or severity of chronic pain was examined.

STUDY APPRAISAL AND SYNTHESIS METHODS

Each study was double coded and evaluated for bias based on the modified Newcastle and Ottawa Scale. Random-effect meta-analyses were conducted to quantify the associations between dysmenorrhea and the presence of chronic pelvic and nonpelvic pain.

RESULTS

Out of 9452 records, 32 studies were included, with 14 reporting associations between dysmenorrhea and chronic pelvic pain, and 20 for dysmenorrhea and chronic nonpelvic pain. Primary dysmenorrhea and endometriosis-associated dysmenorrhea were examined in 7 studies, respectively. More than 30% of the studies were categorized as poor quality, 56% as moderate, and 12.5% as high. Dysmenorrhea was positively associated with both the presence and severity of chronic pelvic and nonpelvic pain conditions. Based on 6689 women from 8 studies, those with chronic pelvic pain had 2.43 (95% confidence interval, 1.98-2.99, I², 42%) times the odds of having dysmenorrhea compared with those without. Based on 3750 women from 11 studies, those with chronic nonpelvic pain had 2.62 (95% confidence interval, 1.84-3.72, I², 72%) times the odds of having dysmenorrhea compared with those without. Overall, dysmenorrhea was associated with 2.50 (95% confidence interval, 2.02-3.10) times the odds of chronic pain, which did not differ by chronic pelvic vs chronic nonpelvic pain, community vs clinical populations, or different geographical regions.

CONCLUSIONS

Dysmenorrhea may be a general risk factor for chronic pain, although whether primary dysmenorrhea increases the risk for chronic pain is unclear. Given that adolescence is a sensitive period for neurodevelopment, elucidating the role of primary dysmenorrhea in pain chronicity in future longitudinal studies is important for preventing both chronic pelvic and nonpelvic pain.

Persistent autonomic dysfunction and bladder sensitivity in primary dysmenorrhea

Menstrual pain, also known as dysmenorrhea, is a leading risk factor for bladder pain syndrome (BPS). A better understanding of the mechanisms that predispose dysmenorrheic women to BPS is needed to develop prophylactic strategies. Abnormal autonomic regulation, a key factor implicated in BPS and chronic pain, has not been adequately characterized in women with dysmenorrhea. Thus, we examined heart rate variability (HRV) in healthy (n = 34), dysmenorrheic (n = 103), and BPS participants (n = 23) in their luteal phase across a bladder-filling task. Both dysmenorrheic and BPS participants reported increased bladder pain sensitivity when compared to controls (p’s < 0.001). Similarly, dysmenorrheic and BPS participants had increased heart rate (p’s < 0.01), increased diastolic blood pressure (p’s < 0.01), and reduced HRV (p’s < 0.05) when compared to controls. Dysmenorrheic participants also exhibited little change in heart rate between maximum bladder capacity and after micturition when compared to controls (p = 0.013). Our findings demonstrate menstrual pain’s association with abnormal autonomic activity and bladder sensitivity, even two weeks after menses. Our findings of autonomic dysfunction in both early episodic and chronic visceral pain states points to an urgent need to elucidate the development of such imbalance, perhaps beginning in adolescence.

Somatic symptoms in women with dysmenorrhea and noncyclic pelvic pain

Somatic symptoms are a robust, transdiagnostic risk factor for pain conditions. However, the extent to which somatic symptoms contribute to the manifestation of the women's pain syndromes, such as dysmenorrhea and noncyclic pelvic pain (NCPP), is unclear due to high rates of co-occurrence. Therefore, the present study investigated the primary hypothesis that somatic symptoms would be elevated in NCPP and distinctly influence the relationship between dysmenorrhea and co-occurring NCPP. A secondary analysis was performed on cross-sectional questionnaire data from 1012 nonpregnant reproductive-aged women. Eligible analyzed participants (n = 834) were categorized into four groups: healthy, dysmenorrhea, NCPP, and NCPP with co-occurring dysmenorrhea (NCPP+dysmenorrhea). A parallel mediation analysis was run to evaluate the primary hypothesis that somatic symptoms are the primary factor associated with increased NCPP accounting for dysmenorrhea. The NCPP+dysmenorrhea group had higher somatic, anxiety, and depression symptom T-scores (respectively 61, 61, 60) compared to the healthy controls (46, 51, 51; p's < .001) and the dysmenorrhea group (50, 53, 54; p's < .001). The pain and psychological symptoms were significantly correlated across the entire sample (r's = .29, - .64, p's < .01). Results from parallel mediation analysis showed that somatic symptoms were distinctly associated with NCPP+dysmenorrhea. Women with NCPP+dysmenorrhea have increased psychological and somatic symptoms compared to women with dysmenorrhea alone. Given that NCPP often co-occurs with dysmenorrhea, failure to account for comorbidity in previous studies has likely led to an overestimation of psychological symptoms in dysmenorrhea. Future studies should evaluate whether somatic sensitivity is a modifiable risk factor for NCPP.

Altered white matter microarchitecture in the cingulum bundle in women with primary dysmenorrhea: A tract-based analysis study

Primary dysmenorrhea (PD), as characterized by painful menstrual cramps without organic causes, is associated with central sensitization and brain function changes. Previous studies showed the integrated role of the default mode network (DMN) in the pain connectome and its key contribution on how an individual perceives and copes with pain disorders. Here, we aimed to investigate whether the cingulum bundle connecting hub regions of the DMN was disrupted in young women with PD. Diffusion tensor imaging was obtained in 41 PD patients and 41 matched healthy controls (HC) during their periovulatory phase. The production of prostaglandins (PGs) was obtained in PD patients during their pain-free and pain phases. As compared with HC, PD patients had similar scores of pain intensity, anxiety, and depression in their pain-free phase. However, altered white matter properties mainly located in the posterior section of the cingulum bundle were observed in PD. Besides PGs being related to menstrual pain, a close relationship was found between the white matter properties of the cingulum bundle during the pain-free phase and the severity of the menstrual pain in PD patients. Our study suggested that PD had trait changes of white matter integrities in the cingulum bundle that persisted beyond the time of menstruation. We inferred that altered anatomical connections may lead to less-flexible communication within the DMN, and/or between the DMN and other pain-related brain networks, which may result in the central susceptibility to develop chronic pain conditions in PD's later life. Hum Brain Mapp 38:4430-4443, 2017. © 2017 Wiley Periodicals, Inc.