Aberrant default mode network in patients with primary dysmenorrhea: a fMRI study

Abnormal Topological Organization of Human Brain Connectome in Primary Dysmenorrhea Patients Using Graph Theoretical Analysis

Background

Accumulating studies have revealed altered brain function and structure in regions linked to sensory, pain and emotion in individuals with primary dysmenorrhea (PD). However, the changes in the topological properties of the brain's functional connectome in patients with PD experiencing chronic pain remain poorly understood.

Purpose

Our study aimed to explore the mechanism of functional brain network impairment in individuals withPD through a graph-theoretic analysis.

Material and Methods

This study was a randomized controlled trial that included individuals with PD and healthy controls (HC) from June 2021 to June 2022. The experiment took place in the magnetic resonance imaging facility at Jiangxi Provincial People's Hospital. Static MRI scans were conducted on 23 female patients with PD and 23 healthy female controls. A two-sample t-test was conducted to compare the global and nodal indices between the two groups, while the Network-Based Statistics (NBS) method was utilized to explore the functional connectivity alterations between the groups.

Results

In the global index, The PD group exhibited decreased Sigma (p = 0.0432) and Gamma (p = 0.0470) compared to the HC group among the small-world network properties.(p<0.05) In the nodal index, the PD group displayed reduced betweenness centrality and increased degree centrality in the default mode network (DMN), along with decreased nodal efficiency and increased degree centrality in the visual network (VN). (P < 0.05, Bonferroni-corrected) Furthermore, in the connection analysis, PD patients showed altered functional connectivity in the basal ganglia network (BGN), VN, and DMN.(NBS corrected).

Conclusion

Our results indicate that individuals with PD showed abnormal brain network efficiency and abnormal connection within DMN, VN and BGN related to pain matrix. These findings have important references for understanding the neural mechanism of pain in PD.

Functional connectivity associations with menstrual pain characteristics in adolescents: an investigation of the triple network model

ABSTRACT

Menstrual pain is associated with deficits in central pain processing, yet neuroimaging studies to date have all been limited by focusing on group comparisons of adult women with vs without menstrual pain. This study aimed to investigate the role of the triple network model (TNM) of brain networks in adolescent girls with varied menstrual pain severity ratings. One hundred participants (ages 13-19 years) completed a 6-min resting state functional magnetic resonance imaging (fMRI) scan and rated menstrual pain severity, menstrual pain interference, and cumulative menstrual pain exposure. Imaging analyses included age and gynecological age (years since menarche) as covariates. Menstrual pain severity was positively associated with functional connectivity between the cingulo-opercular salience network (cSN) and the sensory processing regions, limbic regions, and insula, and was also positively associated with connectivity between the left central executive network (CEN) and posterior regions. Menstrual pain interference was positively associated with connectivity between the cSN and widespread brain areas. In addition, menstrual pain interference was positively associated with connectivity within the left CEN, whereas connectivity both within the right CEN and between the right CEN and cortical areas outside the network (including the insula) were negatively associated with menstrual pain interference. Cumulative menstrual pain exposure shared a strong negative association with connectivity between the default mode network and other widespread regions associated with large-scale brain networks. These findings support a key role for the involvement of TNM brain networks in menstrual pain characteristics and suggest that alterations in pain processing exist in adolescents with varying levels of menstrual pain.

Altered cognitive control network mediates the association between long-term pain and anxiety symptoms in primary dysmenorrhea

Neuroimaging studies have demonstrated the association of the cognitive control network (CCN) with the maintenance of chronic pain. However, whether and how dorsolateral prefrontal cortex (DLPFC), a key region within the CCN, is altered in menstrual pain is unclear. In this study, we aimed to investigate alterations in the DLPFC functional connectivity network in patients with primary dysmenorrhea (PDM). The study comprised 41 PDM patients and 39 matched healthy controls (HCs), all of whom underwent a resting-state functional MRI scan during the menstrual stage. All participants were instructed to complete the clinical assessment before the MRI scan. We used the DLPFC as the seed in resting-state functional connectivity (rsFC) analysis to investigate the difference between PDM patients and HCs. Compared to HCs, PDM patients showed increased right DLPFC rsFC at the bilateral lingual gyrus, dorsal anterior cingulate cortex (dACC), and middle cingulate cortex, and decreased left DLPFC rsFC at the right orbital frontal cortex. In addition, increased right DLPFC-bilateral dACC connectivity mediated the association between disease duration and the self-rating anxiety scale (SAS) scores in PDM patients. We confirmed that the DLPFC-dACC rsFC was associated with higher SAS scores, which could mediate the association between disease duration and anxiety symptoms in patients with PDM. Our findings provide central pathological evidence for an abnormal rsFC of the CCN in PDM patients, which may contribute to a better understanding of the neuropathophysiological mechanisms underlying PDM.

Dysmenorrhea and psychological distress: a meta-analysis

Dysmenorrhea is characterized by pelvic pain associated with menstruation. Similar to people with other pain conditions, females who experience dysmenorrhea report increased psychological distress. However, the pooled magnitude of this association has not been quantified across studies. Accordingly, this meta-analytic review quantifies the magnitude of the associations between dysmenorrhea severity and psychological distress. We conducted a systematic search of the literature using PsycINFO, PubMed, CINHAL, Embase, and Web of Science. Analyzed studies provided observational data on dysmenorrhea severity and anxiety symptoms, depressive symptoms, and/or global psychological distress. A total of 44 studies were included, and three random-effects meta-analyses were conducted, with average pooled effect sizes calculated using Person's r. We found significant, positive associations between measures of dysmenorrhea severity and measures of depressive symptoms (r = 0.216), anxiety symptoms (r = 0.207), and global psychological distress (r = 0.311). Our review suggests that females with greater dysmenorrhea severity experience greater psychological distress. Future directions include defining a clinically meaningful dysmenorrhea severity threshold, understanding the mechanisms and directionality underlying the dysmenorrhea-psychological distress relationship, and designing and testing interventions to jointly address dysmenorrhea and psychological distress.

Assessment of neurotransmitter imbalances within the anterior cingulate cortex in women with primary dysmenorrhea: An initial proton magnetic resonance spectroscopy study

PURPOSE

The neural pathophysiology underlying primary dysmenorrhea (PDM), which leads to poor mode and changes in central pain modulatory systems, remains largely unknown. The objective of this study was to investigate the changes in glutamate/glutamine (Glx) and gamma-aminobutyric acid (GABA+) levels within anterior cingulate cortex (ACC), and their associations with clinical indicators in PDM women.

METHODS

Using 3 T proton magnetic resonance spectroscopy (1H-MRS), we acquired and compared ACC-Glx and ACC-GABA+ levels in PDMs (N = 41) and age- and education-matched healthy controls (HCs) (N = 39) during both the menstrual and periovulatory phases, and between menstrual and periovulatory phases within each group. Total creatine (Cr referencing) level was used as an endogenous reference. The correlations of ACC-neurotransmitter levels with clinical characteristics and the correlations of ACC-Glx with ACC-GABA+ levels in the two groups were analyzed.

RESULTS

Compared to HCs or the periovulatory phase, PDMs exhibited significantly increased ACC-Glx levels (p < 0.05) during the menstrual phase. Positive correlations between GABA+ and Glx levels (r = 0.385, p = 0.025) were found in PDMs during the menstrual phase. ACC-GABA+ levels were associated with self-rating distress scale (SDS) scores (GABA+/Cr: r = 0.369, p = 0.045) and pain catastrophizing scale (PCS) scores (GABA+/Cr: r = 0.373, p = 0.042) in PDM group in only the menstrual phase.

CONCLUSION

Our study represents the first report of ACC-GABA+/Glx imbalances in PDMs during the menstrual phase, which may underlie the mechanisms mediating depression and painful catastrophic symptoms.

Revealing the Central Mechanism of Acupuncture for Primary Dysmenorrhea Based on Neuroimaging: A Narrative Review

Objective

The central mechanism of acupuncture for primary dysmenorrhea was explored by summarizing the changes in different regional networks of the brain induced by acupuncture stimulation by analyzing the existing studies.

Methods

The original studies were collected and selected from three English databases such as PubMed and four Chinese databases as China Knowledge Network (CNKI). The main keyword clusters are neuroimaging, acupuncture, and primary dysmenorrhea.

Results

The literature review yielded 130 possibly qualified studies, and 23 articles fulfilled the criteria for inclusion. Regarding the type of acupuncture studies, 6 moxibustion studies and 17 manual acupuncture studies for primary dysmenorrhea were included. Based on functional magnetic resonance imaging (fMRI), perfusion-weighted imaging (PWI), and positron emission tomography-computer tomography techniques (PET-CT), one or more analysis methods such as amplitude of low-frequency fluctuations (ALFF), regional homogeneity (ReHo), functional connectivity (FC), and independent components analysis (ICA) were used. The results are summarized. To summarize the high-frequency brain area alterations observed in patients with acupuncture-induced primary dysmenorrhea were the anterior cingulate gyrus, thalamus, insula, precentral gyrus, middle frontal gyrus, postcentral gyrus, putamen, and cerebellum.

Conclusion

The results suggest that the mechanism of acupuncture in the treatment of primary dysmenorrhea is the involvement of networks regulating different areas of the brain in the analgesic effects of acupuncture. The brain regions involved in primary dysmenorrhea acupuncture analgesia were mainly located in the pain matrix, default mode network, salience network, and limbic system.

Adaptive neuroplasticity in the default mode network contributing to absence of central sensitization in primary dysmenorrhea

Introduction

Primary dysmenorrhea (PDM), the most prevalent gynecological problem among women of reproductive age, presents as a regular pattern of cyclic menstrual pain. The presence or absence of central sensitization (i.e., pain hypersensitivity) in cases of PDM is a contentious issue. Among Caucasians, the presence of dysmenorrhea is associated with pain hypersensitivity throughout the menstrual cycle, indicating pain amplification mediated by the central nervous system. We previously reported on the absence of central sensitization to thermal pain among Asian PDM females. In this study, functional magnetic resonance imaging was used to reveal mechanisms underlying pain processing with the aim of explaining the absence of central sensitization in this population.

Methods

Brain responses to noxious heat applied to the left inner forearm of 31 Asian PDM females and 32 controls during their menstrual and periovulatory phases were analyzed.

Results and discussion

Among PDM females experiencing acute menstrual pain, we observed a blunted evoked response and de-coupling of the default mode network from the noxious heat stimulus. The fact that a similar response was not observed in the non-painful periovulatory phase indicates an adaptive mechanism aimed at reducing the impact of menstrual pain on the brain with an inhibitory effect on central sensitization. Here we propose that adaptive pain responses in the default mode network may contribute to the absence of central sensitization among Asian PDM females. Variations in clinical manifestations among different PDM populations can be attributed to differences in central pain processing.

Efficacy and cerebral mechanism of acupuncture and moxibustion for treating primary dysmenorrhea: study protocol for a randomized controlled clinical trial

Background

Acupuncture or moxibustion has been proven to be effective for patients with primary dysmenorrhea (PDM). However, the respective advantages and potential central mechanism of acupuncture and moxibustion are worthy of investigating to promote their further application.

Methods

In this randomized controlled neuroimaging trial, 72 patients with PDM will be randomly assigned to three groups: acupuncture treatment group, moxibustion treatment group, and waiting list group. The acupuncture treatment group and moxibustion treatment group will receive acupuncture or moxibustion, respectively, for a total of 3 sessions over 3 consecutive menstrual cycles, and the waiting list group will not take acupuncture or moxibustion during these 3 menstrual cycles. The COX Menstrual Symptom Scale (CMSS), visual analog scale (VAS), and Pain Catastrophizing Scale (PCS) will be used to evaluate the clinical efficacy. The Self-rating Depression Scale (SDS), Self-rating Anxiety Scale (SAS), and 36-Item Short Form Health Survey (SF-36) will be used to assess the mental state and quality of life at baseline and at the end of treatment. Functional magnetic resonance imaging (fMRI) will be performed for detecting the cerebral activity changes at baseline and at the end of the treatment. The clinical data and imaging data will be analyzed among the groups. Correlation analysis will be conducted to investigate the relationship between brain functional changes and symptom improvement.

Discussion

The application of the randomized controlled neuroimaging trial will provide objective and valid evidence about how acupuncture and moxibustion treatment relieve menstrual pain. The results of this study would be useful to confirm the potential similarities and differences between acupuncture and moxibustion in clinical efficacy and central mechanism for patients with PDM.

Trial registration

Chinese Clinical Trial Registry ChiCTR2100043732. Registered on 27 February 2021

Moxibustion for primary dysmenorrhea: A resting-state functional magnetic resonance imaging study exploring the alteration of functional connectivity strength and functional connectivity

Introduction

Primary dysmenorrhea (PDM) is a common gynecological disease and chronic pain disorder. Moxibustion, a form of traditional Chinese medicine therapy, has proven to be effective for PDM. However, the central mechanisms of PDM and moxibustion for PDM are still unclear. This study aims to explore the potential central mechanism of PDM and clarify the possible mechanism of moxibustion for relieving pain.

Materials and methods

A total of 23 PDM patients and 23 matched healthy controls (HCs) were enrolled. For PDM patients, resting-state functional magnetic resonance imaging (rs-fMRI) data were collected pre- and post-moxibustion treatment of 3 consecutive menstrual cycles, respectively. For HCs, rs-fMRI data were collected in the baseline. The resting-state functional connectivity strength (rs-FCS) analysis and the resting-state functional connectivity (rs-FC) analysis based on the region of interest (ROI) were combined to be conducted.

Results

Compared to HCs, PDM patients showed weaker rs-FCS in the left inferior frontal gyrus (IFG). After the moxibustion treatment, rs-FCS in the left IFG was increased with clinical improvement. Then, the left IFG was chosen as ROI, and the rs-FC analysis was conducted. It showed that the left IFG rs-FC in the bilateral anterior cingulate cortex (ACC)/middle cingulate cortex (MCC), the left posterior cingulate cortex (PCC)/precuneus (PCU), and the left parahippocampal gyrus (PHG) decreased after moxibustion treatment, most of which belong to the default mode network (DMN).

Conclusion

Our results highlight the role of the left IFG and the DMN in PDM. Specifically, the central mechanism of moxibustion for analgesia may be related to modulating the disorders of the reappraisal and processing of pain stimuli through influencing the cognition of pain.

Exploration of abnormal dynamic spontaneous brain activity in patients with high myopia via dynamic regional homogeneity analysis

Aim

Patients with high myopia (HM) reportedly exhibit changes in functional brain activity, but the mechanism underlying such changes is unclear. This study was conducted to observe differences in dynamic spontaneous brain activity between patients with HM and healthy controls (HCs) via dynamic regional homogeneity (dReHo) analysis.

Methods

Resting-state functional magnetic resonance imaging (rs-fMRI) scans were performed on 82 patients with HM and 59 HCs who were closely matched for age, sex, and weight. The dReHo approach was used to assess local dynamic activity in the human brain. The association between mean dReHo signal values and clinical symptoms in distinct brain areas in patients with HM was determined via correlation analysis.

Results

In the left fusiform gyrus (L-FG), right inferior temporal gyrus (R-ITG), right Rolandic operculum (R-ROL), right postcentral gyrus (R-PoCG), and right precentral gyrus (R-PreCG), dReHo values were significantly greater in patients with HM than in HCs.

Conclusion

Patients with HM have distinct functional changes in various brain regions that mainly include the L-FG, R-ITG, R-ROL, R-PoCG, and R-PreCG. These findings constitute important evidence for the roles of brain networks in the pathophysiological mechanisms of HM and may aid in the diagnosis of HM.

The Effect of Long-Term Menstrual Pain on Large-Scale Brain Network in Primary Dysmenorrhea Patients

Purpose

Primary dysmenorrhea (PD) is a common gynecological disease, characterized by crampy and suprapubic pain occurring with menses. Growing evidences demonstrated that PD patients were associated with abnormalities in brain function and structure. However, little is known regarding whether the large-scale brain network changes in PD patients. The purpose of this study was to investigate the effect of long-term menstrual pain on large-scale brain network in PD patients using independent component analysis (ICA) method.

Methods

Twenty-eight PD patients (female, mean age, 24.25±1.00 years) and twenty-eight healthy controls (HCs) (mean age, 24.46±1.31 years), closely matched for age, sex, and education, underwent resting-state magnetic resonance imaging scans. ICA was applied to extract the resting-state networks (RSNs) in two groups. Then, two-sample t-tests were conducted to investigate different intranetwork FCs within RSNs and interactions among RSNs between two groups.

Results

Compared to the HC group, PD patients showed significant increased intra-network FCs within the auditory network (AN), sensorimotor network (SMN), right executive control network (RECN). However, PD patients showed significant decreased intra-network FCs within ventral default mode network (vDMN) and salience network (SN). Moreover, FNC analysis showed increased VN-AN and decreased VN-SMN functional connectivity between two groups.

Conclusion

Our study highlighted that PD patients had abnormal brain networks related to auditory, sensorimotor and higher cognitive network. Our results offer important insights into the altered large-scale brain network neural mechanisms of pain in PD patients.

Abnormal interhemispheric functional connectivity in patients with primary dysmenorrhea: a resting-state functional MRI study

BACKGROUND

Neuroimaging studies have confirmed that functional connectivity (FC) disruption of pain-related brain networks may contribute to the cerebral pathophysiology of primary dysmenorrhea (PDM). However, it remains unclear whether FC of symmetrical regions of bilateral hemispheres associated with PDM is abnormal. This functional MRI study aimed to explore the changes of voxel-mirrored homotopic connectivity (VMHC) and seed-based FC in patients with PDM.

METHODS

A cohort comprising patients with PDM (n=35) and healthy controls (HCs) (n=41) underwent resting-state functional MRI scans during their menstrual phase. Interhemispheric FC was compared between the two groups using VMHC analysis. Brain areas with significant group differences in VMHC were selected as seed regions for FC analysis. Correlation analysis was also conducted to examine the relationship between abnormal connectivity of brain regions and clinical measures of pain and anxiety.

RESULTS

Compared with healthy individuals, patients with PDM showed significantly enhanced VMHC in the bilateral orbital part of the superior frontal gyrus and the bilateral middle frontal gyrus. Subsequent seed-based FC analysis showed enhanced connectivity between the aforementioned areas and pain-related brain structures. Hyperconnectivity between the left middle frontal gyrus and the right cingulate gyrus in patients was negatively correlated with an increase in the visual analogue score (VAS) for pain (r=-0.341, P<0.05).

CONCLUSIONS

Our findings indicate that ongoing dysmenorrhea is accompanied by abnormal interhemispheric functional coordination and enhanced connectivity in pain-related regions, attention networks, and the reward system. These findings may provide a novel perspective on the central mechanism of pain caused by PDM.

Analgesia Effect of Verum and Sham Acupuncture Treatments in Primary Dysmenorrhea: A MRI Pilot Study

Acupuncture is an alternative treatment for primary dysmenorrhea (PDM). However, mechanisms by which acupuncture exerts its analgesic properties are still unclear. This study aimed to explore the cerebral blood flow (CBF) response to verum and sham acupuncture treatments, and further investigate whether pre-treatment CBF is capable of assessing symptom changes after interventions. A total of 11 PDM patients in the verum group and 12 patients in the sham group participated in this study. Pain rating index (PRI), CBF, and gonadal hormone levels were acquired before and after 8-week treatments. Both verum and sham acupuncture treatments exert its analgesic effect on PDM after intervention as PRI reduced (p < 0.05). Blood gonadal levels were not significantly different after acupuncture in both groups (all p > 0.05). In the verum group, intervention-related decreases in CBF were observed in the right dorsal anterior cingulate cortex. In the sham group, regions identified as showing reductions in CBF after acupuncture included the left ventromedial prefrontal cortex, left caudate, and left insula. Patients with higher baseline CBF in the left precuneus and right hippocampus were accompanied with worse treatment response to acupuncture intervention. Mechanisms of verum and sham acupuncture treatments are dissimilar as manifested by different brain responses.

Machine Learning Analysis Reveals Abnormal Static and Dynamic Low-Frequency Oscillations Indicative of Long-Term Menstrual Pain in Primary Dysmenorrhea Patients

BACKGROUND

Previous neuroimaging studies demonstrated that patients with primary dysmenorrhea (PD) exhibited dysfunctional resting-state brain activity. However, alterations of dynamic brain activity in PD patients have not been fully characterized.

PURPOSE

Our study aimed to assess the effect of long-term menstrual pain on changes in static and dynamic neural activity in PD patients.

MATERIAL AND METHODS

Twenty-eight PD patients and 28 healthy controls (HCs) underwent resting-state magnetic resonance imaging scans. The amplitude of low-frequency fluctuations (ALFF) and dynamic ALFF was used as classification features in a machine learning approach involving a support vector machine (SVM) classifier.

RESULTS

Compared with the HC group, PD patients showed significantly increased ALFF values in the right cerebellum_crus2, right rectus, left supplementary motor area, right superior frontal gyrus, right supplementary motor area, and left superior frontal medial gyrus. Additionally, PD patients showed significantly decreased ALFF values in the right middle temporal gyrus and left thalamus. PD patients also showed significantly increased dALFF values in the right fusiform, Vermis_10, right middle temporal gyrus, right putamen, right insula, left thalamus, right precentral gyrus, and right postcentral gyrus. Based on ALFF and dALFF values, the SVM classifier achieved respective overall accuracies of 96.36% and 85.45% and respective areas under the curve of 1.0 and 0.95.

CONCLUSION

PD patients demonstrated abnormal static and dynamic brain activities that involved the default mode network, sensorimotor network, and pain-related subcortical nuclei. Moreover, ALFF and dALFF may offer sensitive biomarkers for distinguishing patients with PD from HCs.

Frequency-Specific Alterations in Brain Function in Patients with Primary Dysmenorrhea

OBJECTIVE

Recent neuroimaging studies have found that brain function is abnormal in primary dysmenorrhea (PDM). The present study aimed to explore frequency-specific brain alterations and their occurrence in the PDM.

METHODS

Forty-seven patients with PDM and 36 matched healthy controls were enrolled in the study and underwent resting-state functional magnetic resonance imaging. The alterations in brain function in patients with PDM were assessed using different frequency filter bands (Slow5, Slow4, Slow3, and full low frequency) and functional connectivity density (FCD) approach. The clinical significance of the altered FCD was then explored. Additionally, mediation analysis was employed to detect the altered FCD-mediated clinical relationships in PDM.

RESULTS

Frequency-specific FCD alterations have been observed in patients with PDM, especially in the central executive, default mode, sensorimotor networks, and the hippocampus. The altered full low-frequency FCD in the hippocampus was associated with the duration of disease and pain severity scores. The altered Slow 5 FCD in the second somatosensory area (S2) was associated with the severity of pain in PDM. Furthermore, the FCD in S2 mediated the duration associated with pain symptoms in PDM.

CONCLUSION

The present study identified frequency-specific FCD alterations in PDM and suggested that the S2 area is a potential treatment target for PDM.

Altered Posterior Cerebellar Lobule Connectivity With Perigenual Anterior Cingulate Cortex in Women With Primary Dysmenorrhea

Objectives: This study aimed to investigate the potential connectivity mechanism between the cerebellum and anterior cingulate cortex (ACC) and the cerebellar structure in primary dysmenorrhea (PDM).

Methods: We applied the spatially unbiased infratentorial template (SUIT) of the cerebellum to obtain anatomical details of cerebellar lobules, upon which the functional connectivity (FC) between the cerebellar lobules and ACC subregions was analyzed and the gray matter (GM) volume of cerebellar lobules was measured by using voxel-based morphometry (VBM) in 35 PDM females and 38 age-matched healthy females. The potential relationship between the altered FC or GM volume and clinical information was also evaluated in PDM females.

Results: PDM females showed higher connectivity between the left perigenual ACC (pACC) and lobule vermis_VI, between the left pACC and left lobule IX, and between right pACC and right cerebellar lobule VIIb than did the healthy controls. Compared with healthy controls, no altered GM volume was found in PDM females. No significant correlation was found between altered cerebellum–ACC FC and the clinical variables in the PDM females.

Conclusion: PDM females have abnormal posterior cerebellar connectivity with pACC but no abnormal structural changes. ACC–cerebellar circuit disturbances might be involved in the PDM females.

Immediate Analgesic Effect of Acupuncture in Patients With Primary Dysmenorrhea: A fMRI Study

Primary dysmenorrhea (PDM) is a common gynecological disease characterized by lower abdominal pain. Acupuncture is considered a good alternative therapy for PDM. However, the central mechanism of the analgesic effect of acupuncture is largely unknown. In this study, eligible patients were randomized into the real and sham acupuncture groups using a computer-generated, permuted block randomization method. The study cohort comprised 34 patients: 19 in the real acupuncture group and 15 in the sham acupuncture group. The clinical characteristics of the patients during their menstrual period were collected, and imaging scans were performed during the first 3 days of the patients' menstrual period. We analyzed task and resting functional magnetic resonance imaging (fMRI) data to investigate the potential central mechanism of the immediate effect of acupuncture intervention on the intensity of PDM pain. The task fMRI study found that the rostral anterior cingulate cortex (rACC) and right supplemental motor area were activated during real acupuncture. Using the resting-state functional connectivity (FC) method, we found a post- versus pre-treatment change in the FC of the rACC and left precentral gyrus in the comparison of real acupuncture versus sham acupuncture. In addition, the FC of the rACC-left precentral gyrus at baseline was negatively correlated with short-term analgesia, while the change in the FC of the rACC-left precentral gyrus was positively correlated with short-term analgesia after acupuncture treatment. These findings support the importance of rACC-left precentral gyrus resting-state FC in the modulation of the intensity of PDM pain through acupuncture, which may shed light on the central mechanism of acupuncture in the treatment of PDM.

Functional connectivity of the visual cortex differentiates anxiety comorbidity from episodic migraineurs without aura

Background

Migraine is a common neurological disease that is often accompanied by psychiatric comorbidities. However, the relationship between abnormal brain function and psychiatric comorbidities in migraine patients remains largely unclear. Therefore, the present study sought to explore the correlations between the resting-state functional deficits and psychiatric comorbidities in migraine without aura (MwoA) patients.

Methods

Resting-state functional magnetic resonance images were obtained. In addition, the amplitude of low-frequency fluctuation (ALFF) and regional homogeneity (ReHo) values were obtained. Thereafter regional abnormalities in MwoA patients with and without anxiety (MwoA-A and MwoA-OA) were chosen as seeds to conduct functional connectivity (FC) analysis.

Results

Compared to the healthy controls (HCs), the MwoA-A and MwoA-OA patients had abnormal ALFF and ReHo values in the right lingual gyrus (LG). They also had abnormal FC of the right LG with the ipsilateral superior frontal gyrus (SFG) and middle cingulate cortex (MCC). Additionally, the MwoA-A patients showed higher ReHo values in the left posterior intraparietal sulcus (pIPS) and abnormal FC of the right LG with ipsilateral pIPS and primary visual cortex, compared to the MwoA-OA patients. Moreover, the MwoA-OA patients showed an increase in the FC with the right posterior cingulate cortex/precuneus (PCC/PCUN), left middle frontal gyrus (MFG) and left inferior temporal gyrus (ITG) relative to the HCs. Furthermore, the ALFF values of the right LG positively were correlated with anxiety scores in MwoA-A patients. The abnormal LG-related FCs with the PCC/PCUN, MFG and ITG were negatively associated with the frequency of headaches in MwoA-OA patients.

Conclusions

This study identified abnormal visual FC along with other core networks differentiating anxiety comorbidity from MwoA. This may therefore enhance the understanding of the neuropsychological basis of psychiatric comorbidities and provide novel insights that may help in the discovery of new marks or even treatment targets.

Dynamic network topological properties for classifying primary dysmenorrhoea in the pain-free phase

BACKGROUND

Primary dysmenorrhoea (PDM) is known to alter brain static functional activity. This study aimed to explore the dynamic topological properties (DTP) of dynamic brain functional network in women with PDM in the pain-free phase and their performance in distinguishing PDM in the pain-free phase from healthy controls.

METHODS

Thirty-five women with PDM and 38 healthy women without PDM were included. A dynamic brain functional network was constructed using the slide-window approach. The stability (TP-Stab) and variability (TP-Var) of the DTP of the dynamic functional network were computed using the graph-theory method. A support vector machine (SVM) was used to evaluate the performance of DTP in identifying PDM in the pain-free phase.

RESULTS

Compared with healthy controls, women with PDM had not only lower TP-Stab in global DTP, which included cluster clustering coefficient (C_p ), characteristic path length (L_p ), global efficiency (E_g ) and local efficiency (E_loc ), but also lower TP-Stab and higher TP-Var in nodal DTP (nodal efficiency, E_nod ), mainly in the prefrontal cortex, anterior cingulate cortex, parahippocampal regions and insula. The TP-Stab and TP-Var were significantly correlated with psychological variables, that is positive emotions, sense of control and meaningful existence. SVM analysis showed that the DTP could identify PDM in the pain-free phase from healthy controls with an accuracy of 79.31%, sensitivity of 82.61% and specificity of 76%.

CONCLUSIONS

Women with PDM in the pain-free phase have altered global DTP and nodal DTP, mainly involving pain-related neurocircuits. The highly variable brain network is helpful for identifying PDM in the pain-free phase.

SIGNIFICANCE

This study shows that women with primary dysmenorrhoea (PDM) have decreased stability of dynamic network topological properties (DTP) and increased DTP variability in the pain-free phase. The altered DTP can be used to identify PDM in the pain-free phase. These findings demonstrate the presence of unstable characteristics in the whole network and disrupted pain-related neurocircuits, which might be used as potential classifiers for PDM in the pain-free phase. This study improves our knowledge of the brain mechanisms underlying PDM.

Altered spontaneous brain activity patterns in patients with neovascular glaucoma using amplitude of low-frequency fluctuations: A functional magnetic resonance imaging study

BACKGROUND

Neovascular glaucoma (NVG) can cause irreversible visual impairment and abnormal spontaneous changes in brain's visual system and other systems. There is little research on this aspect at present. However, amplitude of low-frequency fluctuations (ALFFs) can be used as an rs-fMRI analysis technique for testing changes in spontaneous brain activity patterns.

PURPOSE

The aim of this study was to probe the local characteristics of spontaneous brain activity in NVG patients and analyze their correlation with clinical behaviors.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) scans were obtained from eighteen patients with NVG (8 males, 10 females) and eighteen healthy controls (HCs; 8 males and 10 females) who were matched in age, gender, and education level. We evaluated spontaneous brain activity with the ALFF method. A receiver operating characteristic (ROC) curve was used to compare the average ALFF values for altered brain regions of NVG patients with those of HCs.

RESULTS

Compared with HCs, NVG patients had lower ALFF values in the right cuneus, right middle occipital gyrus, left cingulate gyrus, right precuneus, and left medial frontal gyrus (p < 0.001). Higher ALFF values were observed in the right superior frontal gyrus and left middle frontal gyrus (p < 0.001). Analysis of the ROC curves of the brain regions showed that the specificity and accuracy of ALFF values between NVG and HCs in the area under the curve were acceptable (p < 0.001).

CONCLUSION

The patients with NVG exhibited anomalous spontaneous activity in different brain regions; these finding should establish the foundation for a more comprehensive understanding of the pathological mechanisms of NVG. Furthermore, these abnormal variations in specific brain regions can be considered possible clinical indices of NVG.

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.

Aberrant resting-state cerebral blood flow and its connectivity in primary dysmenorrhea on arterial spin labeling MRI

PURPOSE

This study aimed to clarify the resting-state cerebral blood flow alteration patterns induced by primary dysmenorrhea, investigate the relationships between cerebral blood flow alterations and clinical parameters of patients with primary dysmenorrhea, and explore whether brain regions with abnormal cerebral blood flow also feature functional connectivity changes.

METHODS

Arterial spin labeling imaging and clinical parameters were acquired in 42 patients with primary dysmenorrhea and 41 healthy controls during their menstrual phases. Differences in cerebral blood flow were compared between the two groups, and the clusters with significant group differences were selected as the regions of interest for further statistical analyses.

RESULTS

Compared to healthy controls, patients with primary dysmenorrhea exhibited increased cerebral blood flow in the bilateral precuneus, left posterior cingulate cortex, and right rolandic operculum. Among patients with primary dysmenorrhea, we identified a negative correlation between the cerebral blood flow in the right rolandic operculum and the visual analogue score for anxiety, and greater correlation between the functional connectivity in the precuneus/posterior cingulate cortex and the right middle cingulate cortex, and between the right rolandic operculum and the left inferior parietal lobule and the bilateral postcentral gyrus.

DISCUSSION

Cerebral blood flow abnormalities associated with primary dysmenorrhea were mainly concentrated in the areas comprising the default mode network in primary dysmenorrhea patients, which could be involved in the central mechanism of primary dysmenorrhea. Cerebral blood flow alteration in the rolandic operculum may underlie an anxiety-induced compulsive tendency in patients with primary dysmenorrhea. Investigating the enhanced connectivity among various pain-related brain regions could improve understanding of the onset and development of primary dysmenorrhea.

Instant analgesic effect of radial extracorporeal shock wave therapy on primary dysmenorrhoea according to functional magnetic resonance imaging: study protocol for a randomised placebo-controlled trial

BACKGROUND

Primary dysmenorrhoea (PDM) is defined as a series of pain-dominated symptoms during and after menstruation without organic lesions. Nonsteroidal anti-inflammatory drugs and oral contraceptives are usually recommended as first-line therapy for the clinical treatment of PDM, but their widespread long-term application is controversial. Radial extracorporeal shock wave therapy (rESWT) has been widely applied in musculoskeletal rehabilitation because of its secure and noninvasive characteristics and its confirmed effect in improving pain symptoms. This research seeks to explore the efficacy of rESWT for PDM and the changes in brain function of patients with PDM.

METHODS

This clinical research will be a randomised, blind, sham-controlled trial. Thirty-six patients with PDM will be randomly divided into the rESWT group (n = 18) and the sham rESWT group (n = 18). In the rESWT group, treatment will be applied once within 48 h of menstruation at six abdominal myofascial trigger points. The sham rESWT group will receive sham shockwave therapy on the same sites but without energy input. Other dysmenorrhoea-related treatments in both groups will be limited. The main indicators include the short form of the McGill Pain Questionnaire and the Cox Menstrual Symptom Scale. The secondary indicators include the Zung Self-rating Anxiety Scale and Self-rating Depression Scale and functional magnetic resonance imaging (fMRI) changes in brain regions. Results will be evaluated at the screening, at baseline, and before and after treatment, and adverse treatments will be examined. Inter- and intragroup analyses will be performed.

DISCUSSION

This randomised controlled study is designed to explore the immediate efficacy of rESWT for PDM. After rESWT treatment, PDM symptom tests and pain tests, as well as fMRI data, will be investigated for the potential connections between immediate neuroanalgesic mechanisms, which are associated with pain and brain networks. The main results will be used to assess the efficacy of rESWT, and secondary results will focus on improving the neurobiological understanding of disease treatment.

TRIAL REGISTRATION

China Clinical Trial Register, ChiCTR1900020678. Registered on 13 January 2019.

Modular organization of brain resting state networks in patients with classical trigeminal neuralgia

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Sensorimotor network and default mode network activities were lower in trigeminal neuralgia patients and increased after surgery.

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Higher communication between the default mode network module and other modules before surgery was associated with better treatment response.

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Subcortical modules was associated with pain duration.

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A lower connection between the default mode network and subcortical modules was associated with a better treatment response and the thalamus and midcingulate cortex were the major connectors within the subcortical module.

Background

The modular organization of brain networks in trigeminal neuralgia patients has remained largely unknown. We aimed to analyze the brain modules and intermodule connectivity in patients with trigeminal neuralgia before and after percutaneous radiofrequency rhizotomy treatment to identify specific modules that may be associated with the development and brain plasticity of trigeminal neuralgia and to test the ability of modularity analysis to be a predictive imaging biomarker for the treatment effect in patients with trigeminal neuralgia.

Methods

A total of 25 patients with right trigeminal neuralgia and 20 matched healthy subjects were included. Blood-oxygen-level dependent resting state fMRI was used to analyze the brain modular organization.

Results

Whole brain modularity analysis identified seven modules. The metric of intermodule connectivity, participation coefficient, of the sensorimotor network and default mode network modules were significantly lower in patients and increased after surgery. The participation coefficient of the subcortical modules was associated with the pain duration. Higher communication between the default mode network module and other modules before surgery was associated with a better treatment response. Furthermore, the subcortical module was a significant contributor to the participation coefficient relationship of the default mode network module with the treatment response, and the bilateral midcingulate cortex and thalamus were major connectors in the subcortical module.

Conclusions

These findings have important implications regarding the global brain modular responses to chronic neuropathic pain and it may be feasible to use the modularity analysis as part of a risk stratification to predict the treatment response.

Application of amplitude of low‑frequency fluctuation to altered spontaneous neuronal activity in classical trigeminal neuralgia patients: A resting‑state functional MRI study

Recent studies have reported structural and functional abnormalities in multiple brain regions of classical trigeminal neuralgia (CTN) patients. Differences in spontaneous neuronal activity between CTN patients and healthy subjects, however, remain unknown. The aim of the present study was to investigate alterations in brain activity by application of amplitude of low frequency fluctuation (ALFF), thus analyzing the correlation between durations of spontaneous pain intensity and ALFF values in CTN patients. A total of 28 CTN patients (male, n=12; female, n=16) and 28 healthy controls (HCs; male, n=12; female, n=16) matched for age and sex were enrolled. All subjects underwent resting‑state functional magnetic resonance imaging and changes in spontaneous brain activity were investigated using an ALFF method. Receiver operating characteristic (ROC) curve analysis was applied to differentiate ALFF values of CTN patients from HCs. Altered ALFF values and clinical manifestations were evaluated using Pearson's correlation analysis. ALFF values of the bilateral inferior cerebellum, bilateral fusiform gyrus, right precentral gyrus, left inferior temporal gyrus, right superior cerebellum, left inferior occipital gyrus and right superior occipital gyrus were significantly higher in CTN patients when compared to HCs. ROC curve analysis of each brain revealed a near‑perfect AUC accuracy. Pearson's correlation analysis revealed the visual analog scale of the right eye to be positively correlated with both left inferior temporal and occipital gyral findings, while episode duration likewise was positively associated with left inferior temporal gyral findings. CTN patients exhibited abnormal spontaneous activity in multiple brain regions closely related to pain regulation and perception, while VAS and CTN episode duration were positively correlated with ALFF signal values in some brain regions. The present findings provide further insight into the pathological mechanisms underlying CTN.

Altered amplitude of low-frequency fluctuation and regional cerebral blood flow in females with primary dysmenorrhea: a resting-state fMRI and arterial spin labeling study

Purpose: The current study aimed to explore the central mechanism of primary dysmenorrhea (PD) by investigating the alterations in resting state amplitude of low-frequency fluctuation (ALFF) and regional cerebral blood flow (CBF) between PD patients and healthy controls (HCs). Patients and methods: A total of 34 female subjects including 20 PD patients and 14 HCs underwent resting-state functional magnetic resonance imaging (rs-fMRI) and arterial spin labeling technique (ASL) MRI during menstrual phase. Subsequently, the differences in ALFF and CBF were compared in the two groups. The visual analog scores for pain (VAS-P) and for anxiety (VAS-A) were applied to assess cramping pain and related symptoms in PD patients. Finally, Pearson's correlation analysis was performed to analyze relationships between the neuroimaging findings and clinical characteristics. Results: Compared to HCs, PD patients had decreased ALFF in the right cerebellum posterior lobe, right middle temporal gyrus, right parahippocampal gyrus, right hippocampus, right brainstem and left parietal lobe. In addition, elevated CBF values were observed in the right inferior frontal gyrus, right precentral gyrus, and right superior temporal gyrus. There was no significant correlation between ALFF, CBF values and clinical characteristics including onset age of dysmenorrhea, VAS-A, and VAS-P in PD patients. Conclusion: The preliminary alterations of ALFF and CBF values in PD patients were observed in different pain-related brain regions, which were involved in multiple dimensions of pain and pain modulation. The combination of rs-fMRI and ASL MRI might provide complementary information for a better understanding of the central mechanism in PD.

Changes of functional connectivity of the anterior cingulate cortex in women with primary dysmenorrhea

Primary dysmenorrhea (PDM), a common gynecological disorder, is associated with structural and functional alterations in several subregions of the anterior cingulate cortex (ACC). However, systematic functional connectivity of the ACC subregions in PDM has not been clarified. In this study, we used resting-state functional magnetic resonance imaging (fMRI) data from forty-eight PDM patients and thirty-eight matched female healthy controls to investigate the functional connectivity of ACC subregions in PDM. Compared to healthy controls, PDM patients exhibited increased connectivity between the caudal ACC (cACC) and primary somatosensory cortex (SI), between the perigenual ACC (pACC) and caudate, and between the subgenual ACC (sACC) and medial prefrontal cortex (mPFC). PDM patients also showed decreased connectivity between the pACC and precuneus. In PDM group, the connectivity of the right pACC-right caudate positively correlated with disease duration, and the connectivity of the left pACC-left precuneus negatively correlated with disease severity. These present findings reveal that abnormal ACC connectivity may be implicated in the PDM-related disturbances in pain sensory, modulation, and affection. We hope that our study could enhance the understanding of the pathophysiology underlying PDM.

Abnormal reward system network in primary dysmenorrhea

Neuroimaging studies have demonstrated that reward system is associated with chronic pain diseases. In addition, previous studies have also demonstrated abnormal functional and structural brain regions in primary dysmenorrhea. However, the relation of reward system and primary dysmenorrhea is still unknown. Using the resting state functional magnetic resonance imaging, we aimed to investigate the functional connectivity changes of reward system during periovulatory phase in primary dysmenorrhea. Forty-one primary dysmenorrhea patients and 39 matched female healthy controls participated in this study. Compared to healthy controls, primary dysmenorrhea patients showed decreased connectivity of left nucleus accumbens with the bilateral anterior insula and the left amygdala and decreased connectivity of right nucleus accumbens with ventral tegmental area, the left hippocampus, the right orbital frontal cortex, and the right anterior insula. In addition, the decreased functional connectivity between the right nucleus accumbens-ventral tegmental area negatively correlated with the level of prostaglandin F2 alpha. Our findings provide neuroimaging evidence in support of the abnormal reward system connectivity in primary dysmenorrhea patients, which might contribute to a better understanding of the cerebral pathophysiology of primary dysmenorrhea.

Altered intrinsic brain activity in patients with toothaches using the amplitude of low-frequency fluctuations: a resting-state fMRI study

BACKGROUND

The results of previous studies have indicated that pain-associated diseases can result in marked functional and anatomical alterations in the brain. However, differences in spontaneous brain activity occurring in toothache (TA) patients remain unclear.

OBJECTIVE

This study investigated intrinsic brain activity changes in TA subjects using the amplitude of low-frequency fluctuation (ALFF) technique.

METHODS

A total of 18 patients with TA (eight males, and 10 females) and 18 healthy controls (HCs) who were matched for gender, age, and educational status were enrolled. Resting-state functional MRI was used to examine the participants. Spontaneous cerebral activity variations were investigated using the ALFF technique. The mean ALFF values of the TA patients and the HCs were classified using receiver operating characteristic (ROC) curves. The correlations between ALFF signals of distinct regions of the cerebrum and the clinical manifestations of the TA patients were evaluated using Pearson's correlation analysis.

RESULTS

Compared with HCs, TA patients showed notably higher ALFF in the left postcentral gyrus, right paracentral lobule, right lingual gyrus, right inferior occipital gyrus, left fusiform gyrus, and right superior occipital gyrus. ROC curve analysis of each brain region showed that the accuracy area under the curve was excellent. In the TA group, the visual analog scale of the left side was positively correlated with the ALFF signal values of the right paracentral lobule (r=0.639, P=0.025).

CONCLUSION

Multiple brain regions, including pain- and vision-related areas, exhibited aberrant intrinsic brain activity patterns, which may help to explain the underlying neural mechanisms in TA.

Unaltered intrinsic functional brain architecture in young women with primary dysmenorrhea

Primary dysmenorrhea (PDM), painful menstruation without organic causes, is the most prevalent gynecological problem in women of reproductive age. Dysmenorrhea later in life often co-occurs with many chronic functional pain disorders, and chronic functional pain disorders exhibit altered large-scale connectedness between distributed brain regions. It is unknown whether the young PDM females exhibit alterations in the global and local connectivity properties of brain functional networks. Fifty-seven otherwise healthy young PDM females and 62 age- and education-matched control females participated in the present resting-state functional magnetic resonance imaging study. We used graph theoretical network analysis to investigate the global and regional network metrics and modular structure of the resting-state brain functional networks in young PDM females. The functional network was constructed by the interregional functional connectivity among parcellated brain regions. The global and regional network metrics and modular structure of the resting-state brain functional networks were not altered in young PDM females at our detection threshold (medium to large effect size differences [Cohen's d ≥ 0.52]). It is plausible that the absence of significant changes in the intrinsic functional brain architecture allows young PDM females to maintain normal psychosocial outcomes during the pain-free follicular phase.

The OPRM1 A118G polymorphism modulates the descending pain modulatory system for individual pain experience in young women with primary dysmenorrhea

The mu-opioid receptor (OPRM1) A118G polymorphism underpins different pain sensitivity and opioid-analgesic outcome with unclear effect on the descending pain modulatory system (DPMS). Primary dysmenorrhea (PDM), the most prevalent gynecological problem with clear painful and pain free conditions, serves as a good clinical model of spontaneous pain. The objective of this imaging genetics study was therefore to explore if differences in functional connectivity (FC) of the DPMS between the OPRM1 A118G polymorphisms could provide a possible explanation for the differences in pain experience. Sixty-one subjects with PDM and 65 controls participated in the current study of resting-state functional magnetic resonance imaging (fMRI) during the menstruation and peri-ovulatory phases; blood samples were taken for genotyping. We studied 3 aspects of pain experience, namely, mnemonic pain (recalled overall menstrual pain), present pain (spontaneous menstrual pain), and experimental pain (thermal pain) intensities. We report that G allele carriers, in comparison to AA homozygotes, exhibited functional hypo-connectivity between the anterior cingulate cortex (ACC) and periaqueductal gray (PAG). Furthermore, G allele carriers lost the correlation with spontaneous pain experience and exhibited dysfunctional DPMS by means of PAG-seeded FC dynamics. This OPRM1 A118G-DPMS interaction is one plausible neurological mechanism underlying the individual differences in pain experience.