Altered periaqueductal gray resting state functional connectivity in migraine and the modulation effect of treatment

The periaqueductal gray in chronic low back pain: dysregulated neurotransmitters and function

ABSTRACT

Mechanisms underlying chronic pain are insufficiently understood, hampering effective treatment approaches. Preclinical evidence suggests a potential contribution of decreased excitatory (glutamatergic) and increased inhibitory (γ-aminobutyric acid [GABA]ergic) neurotransmission in the periaqueductal gray (PAG), a key descending pain modulatory brainstem area. This magnetic resonance spectroscopy (MRS) study investigated (1) whether a lower excitatory/inhibitory balance is also observed in the PAG of patients with nonspecific chronic low back pain (CLBP) and (2) whether the excitatory/inhibitory balance relates to psychophysical measures of descending pain modulation and pain sensitivity. Magnetic resonance spectroscopy was acquired on a 3T MR system in 41 patients with CLBP and 29 age- and sex-matched controls. Descending pain modulation and pain sensitivity were evaluated using conditioned pain modulation and pressure pain stimuli, respectively, which were both assessed at the lower back as the most painful area and the nondominant hand as a pain-free, remote area. Patients with CLBP presented with a lower glutamate + glutamine (Glx)/GABA ratio compared with controls (P = 0.002), driven by both decreased Glx (P = 0.012) and increased GABA (P = 0.038). Controls with lower Glx/GABA were more sensitive to pressure pain in both areas, but this association was missing in the patients (lower back: P = 0.004; hand: P = 0.002). Patients with more severe clinical pain showed impaired descending pain modulation at the hand (P = 0.003). In line with preclinical evidence, these findings support a dysregulated PAG in patients with CLBP that might be associated with dysfunctional descending pain inhibition.

Periaqueductal gray connectivity in spinal cord injury-induced neuropathic pain

BACKGROUND AND PURPOSE

Neuropathic pain (NP) is a debilitating condition following spinal cord injury (SCI). The role of periaqueductal gray (PAG) in NP development following SCI remains underexplored. Using resting-state functional MRI (rsfMRI), our study aimed to demonstrate the alterations in functional connectivity (FC) of PAG in NP following SCI.

METHODS

Ten SCI patients (SCI + NP, n = 7, and SCI - NP, n = 3), alongside 10 healthy controls (HCs), were enrolled. rsfMRI was conducted followed by seed-to-voxel analysis using PAG as the seed region and then group-based analysis comprising three groups (SCI + NP, SCI - NP, and HC). Age and gender were considered as confounding variables.

RESULTS

Compared to HCs, SCI + NP demonstrated decreased FC between PAG and right insula, right frontal orbital cortex, right pallidum, dorsal raphe nucleus (DRN), red nuclei (RN), substantia nigra (SN), and ventral posterolateral (VPL) thalamic nuclei. Compared to SCI - NP, SCI + NP demonstrated increased FC between PAG and posterior cingulate cortex (PCC), hippocampus, cerebellar vermis lobules IV and V, and thalamic structures (posterior and lateral pulvinar, the mediodorsal nuclei, and the ventral lateral nuclei). Additionally, decreased FC between the PAG and VPL, geniculate bodies, intralaminar nuclei of thalamus, DRN, RN, SN, and prefrontal cortex was observed in this comparison.

CONCLUSIONS

Altered FC between PAG and right anterior insula, VPL, DRN, RN, SN, cerebellar vermis lobules IV and V, frontal cortex, and PCC was associated with NP sequelae of SCI. Additionally, SCI was independently associated with decreased FC between PAG and right posterior insula, cerebellar lobules IV and V, and cerebellar vermis lobules III, IV, and V.

Right-to-left shunt-associated brain functional changes in migraine: evidences from a resting-state FMRI study

Background

Migraine, a neurological condition perpetually under investigation, remains shrouded in mystery regarding its underlying causes. While a potential link to Right-to-Left Shunt (RLS) has been postulated, the exact nature of this association remains elusive, necessitating further exploration.

Methods

The amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), regional homogeneity (ReHo) and functional connectivity (FC) were employed to investigate functional segregation and functional integration across distinct brain regions. Graph theory-based network analysis was utilized to assess functional networks in migraine patients with RLS. Pearson correlation analysis further explored the relationship between RLS severity and various functional metrics.

Results

Compared with migraine patients without RLS, patients with RLS exhibited a significant increase in the ALFF within left middle occipital and superior occipital gyrus; In migraine patients with RLS, significantly reduced brain functional connectivity was found, including the connectivity between default mode network and visual network, ventral attention network, as well as the intra-functional connectivity of somatomotor network and its connection with the limbic network, and also the connectivity between the left rolandic operculum and the right middle cingulate gyrus. Notably, a significantly enhanced functional connectivity between the frontoparietal network and the ventral attention network was found in migraine with RLS; Patients with RLS displayed higher values of the normalized clustering coefficient and greater betweenness centrality in specific regions, including the left precuneus, right insula, and right inferior temporal gyrus. Additionally, these patients displayed a diminished nodal degree in the occipital lobe and reduced nodal efficiency within the fusiform gyrus; Further, the study found positive correlations between ALFF in the temporal lobes, thalamus, left middle occipital, and superior occipital gyrus and RLS severity. Conversely, negative correlations emerged between ALFF in the right inferior frontal gyrus, middle frontal gyrus, and insula and RLS grading. Finally, the study identified a positive correlation between angular gyrus betweenness centrality and RLS severity.

Conclusion

RLS-associated brain functional alterations in migraine consisted of local brain regions, connectivity, and networks involved in pain conduction and regulation did exist in migraine with RLS.

Deciphering nociplastic pain: clinical features, risk factors and potential mechanisms

Nociplastic pain is a mechanistic term used to describe pain that arises or is sustained by altered nociception, despite the absence of tissue damage. Although nociplastic pain has distinct pathophysiology from nociceptive and neuropathic pain, these pain mechanisms often coincide within individuals, which contributes to the intractability of chronic pain. Key symptoms of nociplastic pain include pain in multiple body regions, fatigue, sleep disturbances, cognitive dysfunction, depression and anxiety. Individuals with nociplastic pain are often diffusely tender - indicative of hyperalgesia and/or allodynia - and are often more sensitive than others to non-painful sensory stimuli such as lights, odours and noises. This Review summarizes the risk factors, clinical presentation and treatment of nociplastic pain, and describes how alterations in brain function and structure, immune processing and peripheral factors might contribute to the nociplastic pain phenotype. This article concludes with a discussion of two proposed subtypes of nociplastic pain that reflect distinct neurobiological features and treatment responsivity.

High-definition tDCS over primary motor cortex modulates brain signal variability and functional connectivity in episodic migraine

OBJECTIVE

This study investigated how high-definition transcranial direct current stimulation (HD-tDCS) over the primary motor cortex (M1) affects brain signal variability and functional connectivity in the trigeminal pain pathway, and their association with changes in migraine attacks.

METHODS

Twenty-five episodic migraine patients were randomized for ten daily sessions of active or sham M1 HD-tDCS. Resting-state blood-oxygenation-level-dependent (BOLD) signal variability and seed-based functional connectivity were assessed pre- and post-treatment. A mediation analysis was performed to test whether BOLD signal variability mediates the relationship between treatment group and moderate-to-severe headache days.

RESULTS

The active M1 HD-tDCS group showed reduced BOLD variability in the spinal trigeminal nucleus (SpV) and thalamus, but increased variability in the rostral anterior cingulate cortex (rACC) compared to the sham group. Connectivity decreased between medial pulvinar-temporal pole, medial dorsal-precuneus, and the ventral posterior medial nucleus-SpV, but increased between the rACC-amygdala, and the periaqueductal gray-parahippocampal gyrus. Changes in medial pulvinar variability mediated the reduction in moderate-to-severe headache days at one-month post-treatment.

CONCLUSIONS

M1 HD-tDCS alters BOLD signal variability and connectivity in the trigeminal somatosensory and modulatory pain system, potentially alleviating migraine headache attacks.

SIGNIFICANCE

M1 HD-tDCS realigns brain signal variability and connectivity in migraineurs closer to healthy control levels.

Contralateral acupuncture for migraine without aura: a randomized trial protocol with multimodal MRI

INTRODUCTION

Migraine is a common clinical disorder, ranks as the second most disabling disease worldwide, and often manifests with unilateral onset. Contralateral acupuncture (CAT), as a classical acupuncture method, has been proven to be effective in the treatment of migraine without aura (MWoA). However, its neural mechanisms have not been investigated using multimodal magnetic resonance imaging (MRI).

METHODS AND ANALYSIS

In this multimodal neuroimaging randomized trial, a total of 96 female MWoA participants and 30 female healthy controls (HCs) will be recruited. The 96 female MWoA participants will be randomized into three groups: Group A (CAT group), Group B [ipsilateral acupuncture (IAT) group], and Group C (sham CAT group) in a 1:1:1 allocation ratio. Each group will receive 30 min of treatment every other day, three times a week, for 8 weeks, followed by an 8-week follow-up period. The primary outcome is the intensity of the migraine attack. Data will be collected at baseline (week 0), at the end of the 8-week treatment period (weeks 1-8), and during the 8-week follow-up (weeks 9-16). Adverse events will be recorded. Multimodal MRI scans will be conducted at baseline and after 8-week treatment.

DISCUSSION

This study hypothesized that CAT may treat MWoA by restoring pathological alterations in brain neural activity, particularly by restoring cross-integrated functional connectivity with periaqueductal gray (PAG) as the core pathological brain region. The findings will provide scientific evidence for CAT in the treatment of MWoA.

ETHICS AND DISSEMINATION

The Medical Ethics Committee of the Second Affiliated Hospital of Yunnan University of Chinese Medicine has given study approval (approval no. 2022-006). This trial has been registered with the Chinese Clinical Trials Registry (registration no. ChiCTR2300069456). Peer-reviewed papers will be used to publicize the trial's findings.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/, identifier ChiCTR2300069456.

Abnormal functional hubs in migraine patients: a resting-state MRI analysis about voxel-wise degree centrality

The purpose was to explore the spatial centrality of the whole brain functional network related to migraine and to investigate the potential functional hubs associated with migraine. 32 migraine patients and 55 healthy controls were recruited and they received resting-state functional magnetic resonance imaging voluntarily. Voxel-wise Degree Centrality (DC) was measured across the whole brain, and group differences in DC were compared. False Discovery Rate and permutation test (5000 times) were used for multiple comparisons. Finally, significant differences in functional connectivity (FC) between seeds and other brain regions were further researched by the seed-based approach. The correlation analyses between the changes in the brain function and clinical features were also performed. The results showed that, compared to healthy controls, migraine patients exhibited significantly increased DC in the left anterior cingulate cortex (ACC), slightly increased DC in the right ACC and the right medial superior frontal gyrus (SFG). No significant correlation was found between DC and clinical variables. The seed-based analyses showed that migraine patients showed increased FC between the right SFG and left ACC, decreased FC between the left ACC and left superior temporal gyrus (STG). FC value of the right SFG was positively correlated with the score of migraine-specific quality-of-life questionnaire about role in function-preventive in migraine patients. According to relatively changed DC, we found that migraine patients exhibited specific abnormal intrinsic functional hubs. These findings expand our understanding of functional characteristics of migraine, and may provide new insights into understanding the dysfunction and pathophysiology of migraine patients.

Modulatory effects of acupuncture on raphe nucleus-related brain circuits in patients with chronic neck pain: A randomized neuroimaging trial

OBJECTIVE

Acupuncture has shown promise in treating neck pain. Clinical trials have shown mixed results, possibly due to heterogeneous methodologies and the lack of knowledge regarding underlying brain circuit mechanism of action. In this study, we investigated the specific contribution of the serotonergic system in treating neck pain, and the specific brain circuits involved.

METHODS

A total of 99 patients with chronic neck pain (CNP) were randomized to receive true acupuncture (TA) or sham acupuncture (SA) 3 times weekly for 4 weeks. Patients with CNP in each group were assessed for primary outcomes by measuring the Visual Analog Scale (VAS) and the duration of each attack; secondary outcomes were measured using the Neck Disability Index (NDI), Northwick Park Neck Pain Questionnaire (NPQ), McGill Pain Questionnaire (MPQ), Self-rating Anxiety Scale (SAS), Self-rating Depression Scale (SDS) and the 12-item Short Form Quality Life Scale (SF-12); levels of functional circuits connectivity were assessed using resting-state functional magnetic resonance imaging in the dorsal (DR) and median (MR) raphe nucleus, before and after undergoing acupuncture.

RESULTS

Patients receiving TA showed more extensive symptom improvement compared with SA. Regarding the primary outcomes, changes observed in the TA group were as follows: VAS = 16.9 mm (p < 0.001) and the duration of each attack = 4.30 h (p < 0.001); changes in the SA group: VAS = 5.41 mm (p = 0.138) and the duration of each attack = 2.06 h (p = 0.058). Regarding the secondary outcomes, changes in the TA group: NDI = 7.99 (p < 0.001), NPQ = 10.82 (p < 0.001), MPQ = 4.23 (p < 0.001), SAS = 5.82 (p < 0.001), SDS = 3.67 (p = 0.003), and SF-12 = 3.04 (p < 0.001); changes in the SA group: NDI = 2.97 (p = 0.138), NPQ = 5.24 (p = 0.035) and MPQ = 2.90 (p = 0.039), SAS = 1.48 (p = 0.433), SDS = 2.39 (p = 0.244), and SF-12 = 2.19 (p = 0.038). The modulatory effect of TA exhibited increased functional connectivity (FC) between the DR and thalamus, between the MR and parahippocampal gyrus, amygdala, and insula, with decreased FC between the DR and lingual gyrus and middle frontal gyrus, between the MR and middle frontal gyrus. Furthermore, changes in the DR-related circuit were specifically associated with the intensity and duration of pain, and the MR-related circuit was correlated with the quality of life with CNP.

CONCLUSION

These results demonstrated the effectiveness of TA in treating neck pain and suggested that it regulates CNP by reconfiguring the function of the raphe nucleus-related serotonergic system.

Improving magnetic resonance spectroscopy in the brainstem periaqueductal gray using spectral registration

PURPOSE

Functional understanding of the periaqueductal gray (PAG), a clinically relevant brainstem region, can be advanced using 1 H-MRS. However, the PAG's small size and high levels of physiological noise are methodologically challenging. This study aimed to (1) improve 1 H-MRS quality in the PAG using spectral registration for frequency and phase error correction; (2) investigate whether spectral registration is particularly useful in cases of greater head motion; and (3) examine metabolite quantification using literature-based or individual-based water relaxation times.

METHODS

Spectra were acquired in 33 healthy volunteers (50.1 years, SD = 17.19, 18 females) on a 3 T Philipps MR system using a point-resolved spectroscopy (PRESS) sequence optimized with very selective saturation pulses (OVERPRESS) and voxel-based flip angle calibration (effective volume of interest size: 8.8 × 10.2 × 12.2 mm3 ). Spectra were fitted using LCModel and SNR, NAA peak linewidths and Cramér-Rao lower bounds (CRLBs) were measured after spectral registration and after minimal frequency alignment.

RESULTS

Spectral registration improved SNR by 5% (p = 0.026, median value post-correction: 18.0) and spectral linewidth by 23% (p < 0.001, 4.3 Hz), and reduced the metabolites' CRLBs by 1% to 15% (p < 0.026). Correlational analyses revealed smaller SNR improvements with greater head motion (p = 0.010) recorded using a markerless motion tracking system. Higher metabolite concentrations were detected using individual-based compared to literature-based water relaxation times (p < 0.001).

CONCLUSION

This study demonstrates high-quality 1 H-MRS acquisition in the PAG using spectral registration. This shows promise for future 1 H-MRS studies in the PAG and possibly other clinically relevant brain regions with similar methodological challenges.

Transcutaneous auricular vagus nerve stimulation in the treatment of disorders of consciousness: mechanisms and applications

This review provides an in-depth exploration of the mechanisms and applications of transcutaneous auricular vagus nerve stimulation (taVNS) in treating disorders of consciousness (DOC). Beginning with an exploration of the vagus nerve's role in modulating brain function and consciousness, we then delve into the neuroprotective potential of taVNS demonstrated in animal models. The subsequent sections assess the therapeutic impact of taVNS on human DOC, discussing the safety, tolerability, and various factors influencing the treatment response. Finally, the review identifies the current challenges in taVNS research and outlines future directions, emphasizing the need for large-scale trials, optimization of treatment parameters, and comprehensive investigation of taVNS's long-term effects and underlying mechanisms. This comprehensive overview positions taVNS as a promising and safe modality for DOC treatment, with a focus on understanding its intricate neurophysiological influence and optimizing its application in clinical settings.

The modulation effects of repeated transcutaneous auricular vagus nerve stimulation on the functional connectivity of key brainstem regions along the vagus nerve pathway in migraine patients

Background

Previous studies have shown a significant response to acute transcutaneous vagus nerve stimulation (taVNS) in regions of the vagus nerve pathway, including the nucleus tractus solitarius (NTS), raphe nucleus (RN) and locus coeruleus (LC) in both healthy human participants and migraine patients. This study aims to investigate the modulation effect of repeated taVNS on these brainstem regions by applying seed-based resting-state functional connectivity (rsFC) analysis.

Methods

70 patients with migraine were recruited and randomized to receive real or sham taVNS treatments for 4 weeks. fMRI data were collected from each participant before and after 4 weeks of treatment. The rsFC analyses were performed using NTS, RN and LC as the seeds.

Results

59 patients (real group: n = 33; sham group: n = 29) completed two fMRI scan sessions. Compared to sham taVNS, real taVNS was associated with a significant reduction in the number of migraine attack days (p = 0.024) and headache pain intensity (p = 0.008). The rsFC analysis showed repeated taVNS modulated the functional connectivity between the brain stem regions of the vagus nerve pathway and brain regions associated with the limbic system (bilateral hippocampus), pain processing and modulation (bilateral postcentral gyrus, thalamus, and mPFC), and basal ganglia (putamen/caudate). In addition, the rsFC change between the RN and putamen was significantly associated with the reduction in the number of migraine days.

Conclusion

Our findings suggest that taVNS can significantly modulate the vagus nerve central pathway, which may contribute to the potential treatment effects of taVNS for migraine.Clinical Trial Registration: http://www.chictr.org.cn/hvshowproject.aspx?id=11101, identifier ChiCTR-INR-17010559.

Imaging the brain and vascular reactions to headache treatments: a systematic review

BACKGROUND

Neuroimaging studies have made an important contribution to our understanding of headache pathophysiology. This systematic review aims to provide a comprehensive overview and critical appraisal of mechanisms of actions of headache treatments and potential biomarkers of treatment response disclosed by imaging studies.

MAIN BODY

We performed a systematic literature search on PubMed and Embase databases for imaging studies investigating central and vascular effects of pharmacological and non-pharmacological treatments used to abort and prevent headache attacks. Sixty-three studies were included in the final qualitative analysis. Of these, 54 investigated migraine patients, 4 cluster headache patients and 5 patients with medication overuse headache. Most studies used functional magnetic resonance imaging (MRI) (n = 33) or molecular imaging (n = 14). Eleven studies employed structural MRI and a few used arterial spin labeling (n = 3), magnetic resonance spectroscopy (n = 3) or magnetic resonance angiography (n = 2). Different imaging modalities were combined in eight studies. Despite of the variety of imaging approaches and results, some findings were consistent. This systematic review suggests that triptans may cross the blood-brain barrier to some extent, though perhaps not sufficiently to alter the intracranial cerebral blood flow. Acupuncture in migraine, neuromodulation in migraine and cluster headache patients, and medication withdrawal in patients with medication overuse headache could promote headache improvement by reverting headache-affected pain processing brain areas. Yet, there is currently no clear evidence for where each treatment acts, and no firm imaging predictors of efficacy. This is mainly due to a scarcity of studies and heterogeneous treatment schemes, study designs, subjects, and imaging techniques. In addition, most studies used small sample sizes and inadequate statistical approaches, which precludes generalizable conclusions.

CONCLUSION

Several aspects of headache treatments remain to be elucidated using imaging approaches, such as how pharmacological preventive therapies work, whether treatment-related brain changes may influence therapy effectiveness, and imaging biomarkers of clinical response. In the future, well-designed studies with homogeneous study populations, adequate sample sizes and statistical approaches are needed.

Abnormally Increased Effective Connectivity of the Periaqueductal Gray in Migraine Without Aura Patients

OBJECTIVES

The periaqueductal gray (PAG) is a key region in the descending pain modulatory system. We applied a Granger causality analysis-based approach to examine resting-state effective connectivity of the bilateral PAG regions in migraine patients without aura (MwoA).

MATERIALS AND METHODS

Resting-state functional magnetic resonance imaging data were obtained from 28 MwoA patients and 17 healthy controls. The effective connectivity of the bilateral PAG was characterized using a voxel-wised Granger causality analysis method. The resulting effective connectivity measurements were assessed for correlations with other clinical features.

RESULTS

Compared with the healthy controls, MwoA patients showed increased effective connectivity from the left PAG to the left anterior cingulate gyrus and right postcentral gyrus. Meanwhile, MwoA patients also showed increased effective connectivity from the right PAG to the left precentral gyrus and increased effective connectivity from the left caudate and right middle occipital gyrus to the right PAG.

DISCUSSION

Abnormally increased effective connectivity between PAG and limbic system, primary sensorimotor cortex, and visual cortex may play a key role in neuropathological features, perception, and affection of MwoA. The current study provides further insights into the complex scenario of MwoA mechanisms.

Modulation effects of different treatments on periaqueductal gray resting state functional connectivity in knee osteoarthritis knee pain patients

BACKGROUND

The analgesic effect of acupuncture is widely recognized, but the mechanical characteristics of acupuncture for pain relief, compared to non-steroidal anti-inflammatory (NSAIDs) and placebo medication, remain unknown.

AIMS

To compare the modulation effects of acupuncture treatment with NSAIDs and placebo medication on descending pain modulation system (DPMS) in knee osteoarthritis (KOA) patients.

METHODS

This study recruited 180 KOA patients with knee pain and 41 healthy controls (HCs). Individuals with KOA knee pain were divided randomly into groups of verum acupuncture (VA), sham acupuncture (SA), celecoxib (SC), placebo (PB), and waiting list (WT), with 36 patients in each group. VA and SA groups included ten sessions of puncturing acupoints or puncturing non-acupoints acupuncture treatment for two successive weeks. Celecoxib capsules were continuously given orally to patients in the SC group at a dosage of 200 mg daily for 2 weeks. In the PB group, patients received a placebo capsule once a day for 2 weeks at the same dosage as celecoxib capsules. In the WL group, patients did not receive any treatment. Patients underwent a resting-state BOLD-fMRI scan pre- and post-receiving the therapy, whereas HCs only underwent a baseline scan. Seed (ventrolateral periaqueductal gray, vlPAG, a key node in DPMS) based resting-state functional connectivity (rs-FC) was applied in the data analysis.

RESULTS

All groups demonstrated improved knee pain scores relative to the initial state. There was no statistical difference between the VA and SA groups in all clinical outcomes, and vlPAG rs-FC alterations. KOA knee pain individuals reported higher vlPAG rs-FC in the bilateral thalamus than HCs. KOA knee pain patients in the acupuncture group (verum + sham, AG) exhibited increased vlPAG rs-FC with the right dorsolateral prefrontal cortex (DLPFC) and the right angular, which is associated with knee pain improvement. In contrast with the SC and PB group, the AG exhibited significantly increased vlPAG rs-FC with the right DLPFC and angular. Contrary to the WT group, the AG showed greater vlPAG rs-FC with the right DLPFC and precuneus.

CONCLUSIONS

Acupuncture treatment, celecoxib, and placebo medication have different modulation effects on vlPAG DPMS in KOA knee pain patients. Acupuncture could modulate vlPAG rs-FC with brain regions associated with cognitive control, attention, and reappraisal for knee pain relief in KOA patients, compared with celecoxib and placebo medication.

Longitudinal differences in iron deposition in periaqueductal gray matter and anterior cingulate cortex are associated with response to erenumab in migraine

OBJECTIVES

The objective of this longitudinal study was to determine whether brain iron accumulation, measured using magnetic resonance imaging magnetic transverse relaxation rates (T2*), is associated with response to erenumab for the treatment of migraine.

METHODS

Participants (n = 28) with migraine, diagnosed using international classification of headache disorders 3rd edition criteria, were eligible if they had six to 25 migraine days during a four-week headache diary run-in phase. Participants received two treatments with 140 mg erenumab, one immediately following the pre-treatment run-in phase and a second treatment four weeks later. T2* data were collected immediately following the pre-treatment phase, and at two weeks and eight weeks following the first erenumab treatment. Patients were classified as erenumab responders if their migraine-day frequency at five-to-eight weeks post-initial treatment was reduced by at least 50% compared to the pre-treatment run-in phase. A longitudinal Sandwich estimator approach was used to compare longitudinal group differences (responders vs non-responders) in T2* values, associated with iron accumulation. Group visit effects were calculated with a significance threshold of p = 0.005 and cluster forming threshold of 250 voxels. T2* values of 19 healthy controls were used for a reference. The average of each significant region was compared between groups and visits with Bonferroni corrections for multiple comparisons with significance defined as p < 0.05.

RESULTS

Pre- and post-treatment longitudinal imaging data were available from 28 participants with migraine for a total of 79 quantitative T2* images. Average subject age was 42 ± 13 years (25 female, three male). Of the 28 subjects studied, 53.6% were erenumab responders. Comparing longitudinal T2* between erenumab responders vs non-responders yielded two comparisons which survived the significance threshold of p < 0.05 after correction for multiple comparisons: the difference at eight weeks between the erenumab-responders and non-responders in the periaqueductal gray (mean ± standard error; responders 43 ± 1 ms vs non-responders 32.5 ± 1 ms, p = 0.002) and the anterior cingulate cortex (mean ± standard error; responders 50 ± 1 ms vs non-responders 40 ± 1 ms, p = 0.01).

CONCLUSIONS

Erenumab response is associated with higher T2* in the periaqueductal gray and anterior cingulate cortex, regions that participate in pain processing and modulation. T2* differences between erenumab responders vs non-responders, a measure of brain iron accumulation, are seen at eight weeks post-treatment. Less iron accumulation in the periaqueductal gray and anterior cingulate cortex might play a role in the therapeutic mechanisms of migraine reduction associated with erenumab.

Central Mechanism of Acupuncture Treatment in Patients with Migraine: Study Protocol for Randomized Controlled Neuroimaging Trial

Purpose

Acupuncture has been recognized as an effective and safe alternative therapy for migraine, but its central mechanism has not yet been adequately explained. Meanwhile, research into the clinical efficacy and central mechanism of true acupuncture (TA) and sham acupuncture (SA) is lacking. It is necessary to investigate whether TA has better efficacy than SA, and how they achieve different effects. This study aims to evaluate the efficacy of TA and SA, observe the brain response caused by TA and SA, and further investigate the central nervous mechanism of TA and SA treatment for patients with migraine.

Patients and Methods

This is a randomized controlled neuroimaging trial combining acupuncture treatment with functional magnetic resonance imaging, with patients and outcome assessors blinded. A total of 60 patients with migraine will be randomly allocated to receive 12 sessions of either TA or SA treatments (three sessions per week for 4 weeks), and 30 healthy participants will be recruited as the healthy control (HC) group. Outcome assessment and neuroimaging will be conducted before and after the entire intervention. A headache diary and questionnaires of life quality and psychological properties will be used to evaluate clinical efficacy. Multimodal magnetic resonance imagining data analysis will be used to investigate the central mechanism of TA or SA in treating migraine. Pearson's correlation analysis will be used to reveal the relationship between the brain response and clinical improvements.

Conclusion

The results of this study will reveal the brain response to TA and SA in patients with migraine and contribute to further expanding the knowledge of their central mechanism.

Study Registration

This trial has been approved by the ethics committee of Dongzhimen Hospital affiliated to Beijing University of Chinese Medicine (DZMEC-KY-2020-38) and registered in the Chinese Clinical Trial Registry (registration number ChiCTR2000033995).

The value of brain MRI functional connectivity data in a machine learning classifier for distinguishing migraine from persistent post-traumatic headache

Background

Post-traumatic headache (PTH) and migraine often have similar phenotypes. The objective of this exploratory study was to develop classification models to differentiate persistent PTH (PPTH) from migraine using clinical data and magnetic resonance imaging (MRI) measures of brain structure and functional connectivity (fc).

Methods

Thirty-four individuals with migraine and 48 individuals with PPTH attributed to mild TBI were included. All individuals completed questionnaires assessing headache characteristics, mood, sensory hypersensitivities, and cognitive function and underwent brain structural and functional imaging during the same study visit. Clinical features, structural and functional resting-state measures were included as potential variables. Classifiers using ridge logistic regression of principal components were fit on the data. Average accuracy was calculated using leave-one-out cross-validation. Models were fit with and without fc data. The importance of specific variables to the classifier were examined.

Results

With internal variable selection and principal components creation the average accuracy was 72% with fc data and 63.4% without fc data. This classifier with fc data identified individuals with PPTH and individuals with migraine with equal accuracy.

Conclusion

Multivariate models based on clinical characteristics, fc, and brain structural data accurately classify and differentiate PPTH vs. migraine suggesting differences in the neuromechanism and clinical features underlying both headache disorders.

Bibliometric Analysis of 100 Most Highly Cited Publications on Acupuncture for Migraine

Background

Migraine is a serious global health concern that imposed a huge economic burden on social health care. Over the past few decades, the analgesic effects of acupuncture have been widely recognized, and there is a growing body of research on acupuncture for migraine. Citation analysis is a branch of bibliometrics that helps researchers analyze and identify historical or landmark studies within the scientific literature. Currently, there is no analysis of the 100 most highly cited publications on acupuncture for migraine.

Methods

The 100 most highly cited publications on acupuncture for migraine were screened using the Science Citation Index Expanded of the Web of Science Core Collection database. CiteSpace and VOSviewer programs were used for bibliometric analysis.

Results

A total of 493 publications on acupuncture for migraine were identified. 100 of the most highly cited publications on acupuncture for migraine were published from 1984-2020. These publications were cited 6142 times with an h-index of 44 and 84% were original articles. The highest frequency of citations was 416. A total of 335 authors were involved in the study with 37 lead authors. 212 institutions from 20 countries contributed to the 100 most highly cited publications. The most published studies came from the United States (n=36), followed by China (n=27) and Germany (n=26). The Technical University of Munich published the largest number of papers (n = 15). Top-cited publications mainly came from the Headache (n=13, citations=582). Neuroimaging is gradually emerging as a hot topic of research.

Conclusion

This is the first bibliometric analysis to offer a thorough list of the 100 most highly cited papers on acupuncture for migraine, demonstrating significant progress and emerging trends in this field to assist researchers in determining the direction for further research.

Longitudinal changes in functional connectivity and pain-induced brain activations in patients with migraine: a functional MRI study pre- and post- treatment with Erenumab

Abstract

Background

Migraine involves central and peripheral nervous system mechanisms. Erenumab, an anti-calcitonin gene-related peptide (CGRP) receptor monoclonal antibody with little central nervous system penetrance, is effective for migraine prevention. The objective of this study was to determine if response to erenumab is associated with alterations in brain functional connectivity and pain-induced brain activations.

Methods

Adults with 6–25 migraine days per month during a 4-week headache diary run-in phase underwent pre-treatment brain functional MRI (fMRI) that included resting-state functional connectivity and BOLD measurements in response to moderately painful heat stimulation to the forearm. This was followed by two treatments with 140 mg erenumab, at baseline and 4 weeks later. Post-treatment fMRI was performed 2 weeks and 8 weeks following the first erenumab treatment. A longitudinal Sandwich estimator analysis was used to identify pre- to post-treatment changes in resting-state functional connectivity and brain activations in response to thermal pain. fMRI findings were compared between erenumab treatment-responders vs. erenumab non-responders.

Results

Pre- and post-treatment longitudinal imaging data were available from 32 participants. Average age was 40.3 (+/− 13) years and 29 were female. Pre-treatment average migraine day frequency was 13.8 (+/− 4.7) / 28 days and average headache day frequency was 15.8 (+/− 4.4) / 28 days. Eighteen of 32 (56%) were erenumab responders. Compared to erenumab non-responders, erenumab responders had post-treatment differences in 1) network functional connectivity amongst pain-processing regions, including higher global efficiency, clustering coefficient, node degree, regional efficiency, and modularity, 2) region-to-region functional connectivity between several regions including temporal pole, supramarginal gyrus, and hypothalamus, and 3) pain-induced activations in the middle cingulate, posterior cingulate, and periaqueductal gray matter.

Conclusions

Reductions in migraine day frequency accompanying erenumab treatment are associated with changes in resting state functional connectivity and central processing of extracranial painful stimuli that differ from erenumab non-responders.

Trial registration

clinicaltrials.gov (NCT03773562).

Brain Connectivity Predicts Chronic Pain in Acute Mild Traumatic Brain Injury

OBJECTIVES

Previous studies have established the role of the cortico-mesolimbic and descending pain modulation systems in chronic pain prediction. Mild traumatic brain injury (mTBI) is an acute pain model where chronic pain is prevalent and complicated for prediction. In this study, we set out to study whether functional connectivity (FC) of the nucleus accumbens (NAc) and the periaqueductal gray matter (PAG) is predictive of pain chronification in early-acute mTBI.

METHODS

To estimate FC, resting-state functional magnetic resonance imaging (fMRI) of 105 participants with mTBI following a motor vehicle collision was acquired within 72 hours post-accident. Participants were classified according to pain ratings provided at 12-months post-collision into chronic pain (head/neck pain ≥30/100, n = 44) and recovery (n = 61) groups, and their FC maps were compared.

RESULTS

The chronic pain group exhibited reduced negative FC between NAc and a region within the primary motor cortex corresponding with the expected representation of the area of injury. A complementary pattern was also demonstrated between PAG and the primary somatosensory cortex. PAG and NAc also shared increased FC to the rostral anterior cingulate cortex (rACC) within the recovery group. Brain connectivity further shows high classification accuracy (area under the curve [AUC] = .86) for future chronic pain, when combined with an acute pain intensity report.

INTERPRETATION

FC features obtained shortly after mTBI predict its transition to long-term chronic pain, and may reflect an underlying interaction of injury-related primary sensorimotor cortical areas with the mesolimbic and pain modulation systems. Our findings indicate a potential predictive biomarker and highlight targets for future early preventive interventions. ANN NEUROL 2022;92:819-833.

Comparative efficacy of acupuncture-related therapy for migraine: A systematic review and network meta-analysis

Background

Migraine is a worldwide disabling chronic brain disorder, some studies suggest acupuncture-related therapy plays an important role in raising efficiency rates and reducing migraine attacks. However, clinical trials comparing the efficacy of different interventions for migraine are limited and controversial. This network meta-analysis (NMA) was performed to review all randomized controlled trials (RCTs) comparing the effects of acupuncture-related therapy for migraine.

Methods

Randomized controlled trials (RCTs) of acupuncture-related therapy for migraine were searched in the following databases from the date of database inception to March 31, 2022, including PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), VIP Database, Wanfang Database, and Chinese Biomedical Database (CBM). The primary endpoint was visual analog scale (VAS) scores. The secondary endpoints were the number of migraine days, duration of migraine, and frequency of migraine attacks. We used Cochrane risk of bias to assess the quality of evidence for outcomes.

Results

Thirty-nine studies involving 4379 patients with 13 different acupuncture-related methods were evaluated. According to surface under the cumulative ranking curve value, acupoint injection was ranked the highest (98.0%) in VAS scores, followed by acupoint implantation (79.0%); electroacupuncture was the optimal intervention method (82.4%) in the number of migraine days, followed by embedding needle therapy (73.1%); embedding needle therapy ranked first (99.9%) in the duration of migraine, followed by acupoint injection (77.4%); acupoint injection was the best intervention (99.3%) in the frequency of migraine attacks, followed by conventional acupuncture plus massage (73.8%).

Conclusion

These results provide preliminary evidence that acupuncture-related therapy could be recommended as one of the effective treatments for migraine. Conventional acupuncture has significant effects on improving VAS scores, the number of migraine days, duration of migraine, and frequency of migraine attacks. However, more high-quality studies should be carried out to verify this finding.

Systematic review registration

https://inplasy.com/, identifier: INPLASY202110035.

Therapeutic applications and potential mechanisms of acupuncture in migraine: A literature review and perspectives

Acupuncture is commonly used as a treatment for migraines. Animal studies have suggested that acupuncture can decrease neuropeptides, immune cells, and proinflammatory and excitatory neurotransmitters, which are associated with the pathogenesis of neuroinflammation. In addition, acupuncture participates in the development of peripheral and central sensitization through modulation of the release of neuronal-sensitization-related mediators (brain-derived neurotrophic factor, glutamate), endocannabinoid system, and serotonin system activation. Clinical studies have demonstrated that acupuncture may be a beneficial migraine treatment, particularly in decreasing pain intensity, duration, emotional comorbidity, and days of acute medication intake. However, specific clinical effectiveness has not been substantiated, and the mechanisms underlying its efficacy remain obscure. With the development of biomedical and neuroimaging techniques, the neural mechanism of acupuncture in migraine has gained increasing attention. Neuroimaging studies have indicated that acupuncture may alter the abnormal functional activity and connectivity of the descending pain modulatory system, default mode network, thalamus, frontal-parietal network, occipital-temporal network, and cerebellum. Acupuncture may reduce neuroinflammation, regulate peripheral and central sensitization, and normalize abnormal brain activity, thereby preventing pain signal transmission. To summarize the effects and neural mechanisms of acupuncture in migraine, we performed a systematic review of literature about migraine and acupuncture. We summarized the characteristics of current clinical studies, including the types of participants, study designs, and clinical outcomes. The published findings from basic neuroimaging studies support the hypothesis that acupuncture alters abnormal neuroplasticity and brain activity. The benefits of acupuncture require further investigation through basic and clinical studies.

Efficacy prediction of acupuncture treatment for migraine without aura based on multimodal MRI: A study protocol

Introduction

Acupuncture is an effective and safe therapy for patients with migraine without aura (MwoA), but only 41–59% of patients show improvement with this treatment. Screening positive responders to acupuncture treatment for MwoA can ensure that healthcare resources can be appropriately targeted to specific patients who would most benefit. The objective of this study is to determine whether the structure and functional activity in certain brain regions can predict analgesia response in patients with MwoA who receive acupuncture treatment.

Methods and analysis

A total of 72 patients with MwoA and 72 healthy controls (HCs) will be enrolled in this study. Resting-state structural and functional magnetic resonance imaging (MRI) data will be collected from each participant at baseline. Patients with MwoA will undergo 12 sessions of acupuncture treatment for 8 weeks, twice per week in the first 4 weeks and once per week for the last 4 weeks. The follow-up will be 12 weeks. The number of days with migraine, frequency of migraine attacks, and average visual analog scale scores will be recorded in detail at weeks 0, 4, 8, 12, and 16 and at the end of follow-up (week 20). The positive response rate will be calculated as the proportion of patients with ≥50% reduction in the number of migraine days during follow-up compared with baseline. Machine learning methods will be applied to classify patients with MwoA and HCs and predict patients with response or non-response to acupuncture treatment based on multimodal MRI parameters, such as gray matter volume, regional homogeneity, amplitude of low-frequency fluctuation, fractional anisotropy, and mean diffusivity.

Discussion

This study aims to establish brain structural and functional characteristics that can identify patients with MwoA who will derive analgesia benefits from acupuncture treatment.

Trial registration number

http://www.chictr.org.cn/showproj.aspx?proj=65443, identifier: ChiCTR2100042915.

Migraine and Posttraumatic Headache: Similarities and Differences in Brain Network Connectivity

Posttraumatic headache (PTH) is the most common symptom following mild traumatic brain injury (mTBI) (also known as concussion). Migraine and PTH have similar phenotypes, and a migraine-like phenotype is common in PTH. The similarities between both headache types are intriguing and challenge a better understanding of the pathophysiological commonalities involved in migraine and PTH due to mTBI. Here, we review the PTH resting-state functional connectivity literature and compare it to migraine to assess overlap and differences in brain network function between both headache types. Migraine and PTH due to mTBI have overlapping and disease-specific widespread alterations of static and dynamic functional networks involved in pain processing as well as dysfunctional network connections between frontal regions and areas of pain modulation and pain inhibition. Although the PTH functional network literature is still limited, there is some evidence that dysregulation of the top-down pain control system underlies both migraine and PTH. However, disease-specific differences in the functional circuitry are observed as well, which may reflect unique differences in brain architecture and pathophysiology underlying both headache disorders.

Cortical abnormalities in patients with fibromyalgia: a pilot study of surface-based morphometry analysis

BACKGROUND

Although neuroanatomical studies correlated to fibromyalgia (FM) are gaining increasing interest, the cortical morphology of patients are largely unknown, and data on cortical gyrification are scarce. The objective of the present study is to assess the cortical morphology in female patients with FM compared with healthy controls (HC) using surface-based morphometry (SBM) analysis of magnetic resonance imaging (MRI).

METHODS

T1-MRIs and clinical data of 20 FM patients and 20 HC subjects were obtained from a public databset via OpenNeuro. For each subject, surface parameters including cortical thickness, local gyrification index (LGI), sulcal depth, and fractal dimensionality were estimated using SBM analysis. These data were compared between two groups controlled by age. The correlations between regional SBM parameters showing group differences and clinical profiles were analyzed.

RESULTS

Compared with HC subjects, FM patients showed reduced cortical thickness in right primary motor cortex, lower LGI in right rostral anterior cingulate and higher sulcal depth in right precuneus (p < 0.05 cluster level family- wise error corrected). In FM patients, correlation analysis showed that the cortical thickness in right primary motor cortex were inversely correlated with scores of pain catastrophizing scale (r = -0.498, p = 0.030) and pain self-perception scale (r = -0.527, p = 0.020), and disease duration (r = -0.488, p = 0.034), respectively.

CONCLUSIONS

Our findings provide evidence of neuroanatomical aberrations in FM patients, which may provide insight into the neuropathology of FM.

The cumulative therapeutic effect of acupuncture in patients with migraine without aura: Evidence from dynamic alterations of intrinsic brain activity and effective connectivity

We explored the dynamic alterations of intrinsic brain activity and effective connectivity after acupuncture treatment to investigate the underlying neurological mechanism of acupuncture treatment in patients with migraine without aura (MwoA). The Functional Magnetic Resonance Imaging (fMRI) scans were separately obtained at baseline, after the first and 12th acupuncture sessions in 40 patients with MwoA. Compared with the healthy controls (HCs), patients with MwoA mostly showed a decreased dynamic amplitude of low-frequency fluctuation (dALFF) variability in the rostral ventromedial medulla (RVM), superior lobe of left cerebellum (Cerebellum_Crus1_L), right precuneus (PCUN.R), and so on. The decreased dALFF variability of RVM, Cerebellum_Crus1_L, and PCUN.R progressively recovered after the first and 12th acupuncture treatment sessions as compared to the baseline. There was gradually increased dynamic effective connectivity (DEC) variability in RVM outflow to the right middle frontal gyrus, left insula, right precentral gyrus, and right supramarginal gyrus, and gradually enhanced DEC variability from the right fusiform gyrus inflow to RVM. Furthermore, the gradually increased DEC variability was found from Cerebellum_Crus1_L outflow to the left middle occipital gyrus and the left precentral gyrus, from PCUN.R outflow to the right thalamus. These dALFF variabilities were positively correlated with the frequency of migraine attacks and negatively correlated with disease duration at baseline. The dynamic Granger causality analysis (GCA) coefficients of this DEC variability were positively correlated with Migraine-Specific Quality of Life Questionnaire scores and negatively correlated with the frequency of migraine attacks and visual analog scale (VAS) scores after 12th acupuncture sessions. Our results were analyzed by a longitudinal fMRI in the absence of a sham acupuncture control group and provided insight into the dynamic alterations of brain activity and effective connectivity in patients with MwoA after acupuncture intervention. Acupuncture might relieve MwoA by increasing the effective connectivity of RVM, Cerebellum_Crus1_L, and PCUN.R to make up for the decreased dALFF variability in these brain areas.

Propagation Structure of Intrinsic Brain Activity in Migraine without Aura

Previous studies have revealed highly reproducible patterns of temporally lagged brain activity in healthy human adults. However, it is unknown whether temporal organization of intrinsic activity is altered in migraines or if it relates to migraine chronification. In this resting-state functional magnetic resonance imaging study, temporal features of intrinsic activity were investigated using resting-state lag analysis, and 39 episodic migraine patients, 17 chronic migraine patients, and 35 healthy controls were assessed. Temporally earlier intrinsic activity in the hippocampal complex was revealed in the chronic migraine group relative to the other two groups. We also found earlier intrinsic activity in the medial prefrontal cortex in chronic compared with episodic migraines. Both migraine groups showed earlier intrinsic activity in the lateral temporal cortex and sensorimotor cortex compared with the healthy control group. Across all patients, headache frequency negatively correlated with temporal lag of the medial prefrontal cortex and hippocampal complex. Disrupted propagation of intrinsic activity in regions involved in sensory, cognitive and affective processing of pain may contribute to abnormal brain function during migraines. Decreased time latency in the lateral temporal cortex and sensorimotor cortex may be common manifestations in episodic and chronic migraines. The temporal features of the medial prefrontal cortex and hippocampal complex were associated with migraine chronification.

Efficacy of contralateral acupuncture in women with migraine without aura: protocol for a randomised controlled trial

INTRODUCTION

Migraine is a common neurological disorder with a higher prevalence occurring in women. Migraine without aura (MwoA) is the most common type of migraine. In recent years, the safety and effectiveness of acupuncture for migraines have been internationally recognised. Contralateral acupuncture (CAT) (Jùcì) is an ancient classic acupuncture technique from Huang Di Nei Jing that refers to the acupoints on the right side (healthy side) selected for diseases on the left (affected side) and vice versa. Some studies have shown that efficacy of CAT on the painful disorder is even better than ipsilateral acupuncture (IAT), but there remains a lack of high-quality evidence to support it.

METHODS AND ANALYSIS

This is a single-centre, randomised and sham-controlled clinical trial in China with three parallel groups that aim to evaluate the efficacy of CAT in women with unilateral MwoA. 243 participants will be randomly divided into the experimental group (CAT group), control group 1 (IAT group) and control group 2 (sham acupuncture group) (1:1:1 allocation ratio). Each group will be given 30-minute treatment sessions, once every other day, approximately three times per week, for a total of 24 treatments and follow-up visits two times. The primary outcome is the changes in days of migraine attacks. The secondary outcomes are frequency of migraine attacks, intensity of migraine, migraine duration, the dose of intake of acute medication, the Migraine-Specific Quality of Life Questionnaire, the Migraine Disability Assessment Score, the Headache Impact Test-6 and the Pittsburgh Sleep Quality Index. The data will be collected at the baseline time (week 0), end of treatment (week 4-8) and the follow-up time (week 12-16). Adverse events will be collected and recorded during each treatment.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the Ethics Committee of the Sports Trauma Specialist Hospital of Yunnan Province (2021-01). All participants will provide written informed consent before randomisation. The results of this study will be published in a peer-reviewed journal and presented at conferences.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registration Center (ChiCTR2100051479).

Tonic pain alters functional connectivity of the descending pain modulatory network involving amygdala, periaqueductal gray, parabrachial nucleus and anterior cingulate cortex

INTRODUCTION

Resting state functional connectivity (FC) is widely used to assess functional brain alterations in patients with chronic pain. However, reports of FC accompanying tonic pain in pain-free persons are rare. A network we term the Descending Pain Modulatory Network (DPMN) is implicated in healthy and pathologic pain modulation. Here, we evaluate the effect of tonic pain on FC of specific nodes of this network: anterior cingulate cortex (ACC), amygdala (AMYG), periaqueductal gray (PAG), and parabrachial nuclei (PBN).

METHODS

In 50 pain-free participants (30F), we induced tonic pain using a capsaicin-heat pain model. functional MRI measured resting BOLD signal during pain-free rest with a 32°C thermode and then tonic pain where participants experienced a previously warm temperature combined with capsaicin. We evaluated FC from ACC, AMYG, PAG, and PBN with correlation of self-report pain intensity during both states. We hypothesized tonic pain would diminish FC dyads within the DPMN.

RESULTS

Of all hypothesized FC dyads, only PAG and subgenual ACC was weakly altered during pain (F=3.34; p=0.074; pain-free>pain d=0.25). After pain induction sACC-PAG FC became positively correlated with pain intensity (R=0.38; t=2.81; p=0.007). Right PBN-PAG FC during pain-free rest positively correlated with subsequently experienced pain (R=0.44; t=3.43; p=0.001). During pain, this connection's FC was diminished (paired t=-3.17; p=0.0026). In whole-brain analyses, during pain-free rest, FC between left AMYG and right superior parietal lobule and caudate nucleus were positively correlated with subsequent pain. During pain, FC between left AMYG and right inferior temporal gyrus negatively correlated with pain. Subsequent pain positively correlated with right AMYG FC with right claustrum; right primary visual cortex and right temporo-occipitoparietal junction Conclusion: We demonstrate sACC-PAG tonic pain FC positively correlates with experienced pain and resting right PBN-PAG FC correlates with subsequent pain and is diminished during tonic pain. Finally, we reveal PAG- and right AMYG-anchored networks which correlate with subsequently experienced pain intensity. Our findings suggest specific connectivity patterns within the DPMN at rest are associated with subsequently experienced pain and modulated by tonic pain. These nodes and their functional modulation may reveal new therapeutic targets for neuromodulation or biomarkers to guide interventions.

Effect of Acupuncture on the Cognitive Control Network of Patients with Knee Osteoarthritis: Study Protocol for a Randomized Controlled Trial

Purpose

Materials and Methods

Discussion

Study Registration

Clinical Effects of Repetitive Transcranial Magnetic Stimulation of the Motor Cortex Are Associated With Changes in Resting-State Functional Connectivity in Patients With Fibromyalgia Syndrome

In this double-blinded, sham-controlled, counterbalanced, and crossover study, we investigated the potential neuroplasticity underlying pain relief and daily function improvements following repetitive transcranial magnetic stimulation of the motor cortex (M1-rTMS) in fibromyalgia syndrome (FMS) patients. Specifically, we used magnetic resonance imaging (MRI) to examine changes in brain structural and resting-state functional connectivity (rsFC) that correlated with improvements in FMS symptomology following M1-rTMS. Twenty-seven women with FMS underwent real and sham treatment series, each consisting of 10 daily treatments of 10Hz M1-rTMS over 2 weeks, with a washout period in between. Before and after each series, participants underwent anatomical and resting-state functional MRI scans and questionnaire assessments of FMS-related clinical pain and functional and psychological burdens. The expected reductions in FMS-related symptomology following M1-rTMS occurred with the real treatment only and correlated with rsFC changes in brain areas associated with pain processing and modulation. Specifically, between the ventromedial prefrontal cortex and the M1 (t = -5.54, corrected P = .002), the amygdala and the posterior insula (t = 5.81, corrected P = .044), and the anterior and posterior insula (t = 6.01, corrected P = .029). Neither treatment significantly changed brain structure. Therefore, we provide the first evidence of an association between the acute clinical effects of M1-rTMS in FMS and functional alterations of brain areas that have a significant role in the experience of chronic pain. Structural changes could potentially occur over a more extended treatment period. PERSPECTIVE: We show that the neurophysiological mechanism of the improvement in fibromyalgia symptoms following active, but not sham, rTMS applied to M1 involves changes in resting-state functional connectivity in sensory, affective and cognitive pain processing brain areas, thus substantiating the essence of fibromyalgia syndrome as a treatable brain-based disorder.

Abnormalities of Thalamic Functional Connectivity in Patients with Migraine: A Resting-State fMRI Study

Introduction

Migraine is a common headache disorder. Many studies have used magnetic resonance imaging (MRI) to explore the possible pathogenesis of migraine, but they have not reached consistent conclusions and lack rigorous multiple comparison correction. Thus, this study investigates the mechanisms of migraine development from the perspective of altered functional connectivity (FC) in brain regions by using data-driven and regions of interest (ROI)-based approaches.

Methods

Resting-state functional MRI data were collected from 30 patients with migraine and 40 healthy controls (HCs) matched for age, gender, and years of education. For the data-driven method, we used a voxel-mirrored homotopic connectivity (VMHC) approach to compare the FC between the patients and HCs. For the ROI-based method, significant differences in VMHC maps between the patients and HCs were defined as ROI. The seed-based approach further revealed significant differences in FC between the seeds and the other brain regions. Furthermore, the correlations between abnormal FC and clinical characteristics of patients were investigated. A rigorous multiple comparison correction was used with false discovery rate and permutation test (5000 times).

Results

In comparison with the controls group, patients showed enhanced VMHC in the bilateral thalamus. We also observed enhanced FC between the left thalamus and the left superior frontal gyrus, and increased FC between the right thalamus and the left middle frontal gyrus (Brodmann area 45 and Brodmann area 8) in patients. Further analysis showed that the FC values in the left superior frontal gyrus and left middle frontal gyrus were negatively corrected with visual analogue scale scores or attack times for headaches.

Conclusions

Patients with migraine showed altered VMHC in the bilateral thalamus, and abnormal FC of bilateral thalamus and other brain regions. The abnormalities in thalamic FC are a likely mechanism for the development of migraine.

Trial Registration

Chinese Clinical Trial Registry, ChiCTR2000033995. Registered on 20 June 2020.

Early Fractional Amplitude of Low Frequency Fluctuation Can Predict the Efficacy of Transcutaneous Auricular Vagus Nerve Stimulation Treatment for Migraine Without Aura

Migraine is a common primary headache disorder. Transcutaneous auricular vagus nerve stimulation (taVNS) has been verified to be effective in patients with migraine without aura (MWoA). However, there are large interindividual differences in patients’ responses to taVNS. This study aimed to explore whether pretreatment fractional amplitude of low frequency fluctuation (fALFF) features could predict clinical outcomes in MWoA patients after 4-week taVNS. Sixty MWoA patients and sixty well-matched healthy controls (HCs) were recruited, and migraineurs received 4-week taVNS treatment. Resting-state functional magnetic resonance imaging (rs-fMRI) data were collected, and the significant differences of fALFF were detected between MWoA patients and HCs using two-sample t-test. A mask of these significant regions was generated and used for subsequent analysis. The abnormal fALFF in the mask was used to predict taVNS efficacy for MWoA using a support vector regression (SVR) model combining with feature select of weight based on the LIBSVM toolbox. We found that (1) compared with HCs, MWoA patients exhibited increased fALFF in the left thalamus, left inferior parietal gyrus (IPG), bilateral precentral gyrus (PreCG), right postcentral gyrus (PoCG), and bilateral supplementary motor areas (SMAs), but decreased in the bilateral precuneus and left superior frontal gyrus (SFG)/medial prefrontal cortex (mPFC); (2) after 4-week taVNS treatment, the fALFF values significantly decreased in these brain regions based on the pretreatment comparison. Importantly, the decreased fALFF in the bilateral precuneus was positively associated with the reduction in the attack times (r = 0.357, p = 0.005, Bonferroni correction, 0.05/5), whereas the reduced fALFF in the right PoCG was negatively associated with reduced visual analog scale (VAS) scores (r = −0.267, p = 0.039, uncorrected); (3) the SVR model exhibited a good performance for prediction (r = 0.411, p < 0.001),which suggests that these extracted fALFF features could be used as reliable biomarkers to predict the treatment response of taVNS for MWoA patients. This study demonstrated that the baseline fALFF features have good potential for predicting individualized treatment response of taVNS in MWoA patients, and those weight brain areas are mainly involved in the thalamocortical (TC) circuits, default mode network (DMN), and descending pain modulation system (DPMS). This will contribute to well understanding the mechanism of taVNS in treating MWoA patients and may help to screen ideal patients who respond well to taVNS treatment.

Efficacy of Acupuncture Treatment of Migraine Delivered by Senior or Junior Acupuncturists: Study Protocol for a Randomized Controlled Trial

INTRODUCTION

Acupuncture is an efficacious and safe treatment choice for migraine prevention. Results from clinical trials have shown that non-specific effects play an important role in acupuncture's efficacy. To date, however, there is no evidence available quantitatively evaluating the effect of non-specific effects, such as patients' expectations and beliefs for acupuncturists, on acupuncture efficacy, necessitating further exploration.

METHODS

A total of 156 patients with migraine without aura (MwoA) will be randomized to either junior or senior acupuncturist group, at a ratio of 1:1. The study will last 24 weeks, for each patient, comprising baseline, treatment, and follow-up phases lasting 4, 8, and 12 weeks, respectively. All patients will undergo 12 sections of acupuncture treatment delivered by either a junior or senior acupuncturist following the same acupuncture prescription and manipulation. The primary outcomes will be changes in the number of migraine days and frequency of attacks per 4 weeks cycle, relative to the baseline. Secondary outcomes will include severity of headache pain, quality of life, anxiety/depression levels, and use of non-steroidal anti-inflammatory drugs (NSAIDs) per 4 weeks cycle, compared to the baseline, as well as adverse events and rate of positive response to treatment. Prior to randomization of patients into junior or senior acupuncturist groups, the Acupuncture Expectations Evaluation Scale (AES) will be used to evaluate their expectations and belief with regards to acupuncture efficacy delivered by senior or junior acupuncturists.

DISCUSSION

Results from this clinical randomized controlled trial will help to quantitatively evaluate the extent of the effect of acupuncture treatment delivered by a senior or junior acupuncturist (high relative to low expectations) in migraine patients.

ETHICS AND DISSEMINATION

This trial has been approved by the Institutional Review Boards and Ethics Committees of Hospital of Chengdu University of Traditional Chinese Medicine (Approval No. 2020KL-058).

Acupuncture Enhances Dorsal Raphe Functional Connectivity in Knee Osteoarthritis With Chronic Pain

INTRODUCTION

Knee osteoarthritis is a common disease in the elderly. Patients suffer from long-term chronic pain and reduced life quality. Acupuncture has been proven to be an effective treatment for KOA. However, the neural mechanism of acupuncture is unclear, so far. Periaqueductal gray (PAG) and raphe nuclei (RPN) are essential structures associated with chronic pain in human brains. This study aims to investigate functional connectivity (FC) changes of PAG and RPN in KOA to interpret the neural mechanism of acupuncture.

METHODS

In 15 patients with KOA and 15 healthy controls (HC), we acquired Visual Analog Scale (VAS) scores and resting-state fMRI images of each participant before and after acupuncture stimulation on EX-LE5 acupoint. Then, PAG and RPN were selected as seeds to perform FC analysis based on resting-state fMRI images. Finally, we compared FC patterns of PAG and RPN between patients with KOA and HC, then between pre-acupuncture and post-acupuncture. Correlations between FC values and VAS scores were calculated as well.

RESULTS

For PAG, FC of patients with KOA was lower in the right lingual gyrus at post-acupuncture compared with HC (p <0.001, uncorrected). For dorsal RPN, FC of patients with KOA was significantly higher in right putamen at post-acupuncture compared with HC (p <0.001, corrected with FDR), and FC changes were significant between pre-acupuncture and post-acupuncture in patients with KOA. Post-acupuncture FC values between dorsal RPN and right putamen were correlated with VAS scores. For medial RPN, FC of patients with KOA was lower in the right cerebellum at post-acupuncture compared with HC (p <0.001, uncorrected), but no significant FC changes were found between pre-acupuncture and post-acupuncture in patients with KOA. FC values between medial RPN and right cerebellum were not correlated with VAS scores at pre-acupuncture and post-acupuncture.

DISCUSSION

Our study demonstrated that acupuncture enhanced FC between dorsal RPN and the right putamen in patients with KOA, which was associated with chronic pain intensity. This result suggests that acupuncture stimulation can enhance FC between dorsal raphe and striatum, illustrating a neural mechanism that acupuncture can drive the patients' brain, with KOA, to perceive pain.

Association of plasma tryptophan concentration with periaqueductal gray matter functional connectivity in migraine patients

Altered periaqueductal gray matter (PAG) functional connectivity contributes to brain hyperexcitability in migraine. Although tryptophan modulates neurotransmission in PAG projections through its metabolic pathways, the effect of plasma tryptophan on PAG functional connectivity (PAG-FC) in migraine has not been investigated yet. In this study, using a matched case-control design PAG-FC was measured during a resting-state functional magnetic resonance imaging session in migraine without aura patients (n = 27) and healthy controls (n = 27), and its relationship with plasma tryptophan concentration (TRP) was assessed. In addition, correlations of PAG-FC with age at migraine onset, migraine frequency, trait-anxiety and depressive symptoms were tested and the effect of TRP on these correlations was explored. Our results demonstrated that migraineurs had higher TRP compared to controls. In addition, altered PAG-FC in regions responsible for fear-cascade and pain modulation correlated with TRP only in migraineurs. There was no significant correlation in controls. It suggests increased sensitivity to TRP in migraine patients compared to controls. Trait-anxiety and depressive symptoms correlated with PAG-FC in migraine patients, and these correlations were modulated by TRP in regions responsible for emotional aspects of pain processing, but TRP did not interfere with processes that contribute to migraine attack generation or attack frequency.

Bibliometric Analysis of Functional Magnetic Resonance Imaging Studies on Acupuncture Analgesia Over the Past 20 Years

BACKGROUND

Researches on the central mechanisms of acupuncture analgesia have been widely conducted worldwide. However, there is no bibliometric analysis of functional magnetic resonance imaging (fMRI) studies on acupuncture analgesia. This study visualized the current status, hot spots and frontiers of fMRI studies on acupuncture analgesia in the past 20 years to provide a theoretical basis for its clinical application.

METHODS

All publications were obtained from Science Citation Index-Expanded (SCI-E) of Web of Science (WOS). We used CiteSpace to analyze publications, journals, cited journals, authors, cited authors, institutions, countries, references, and keywords. We also analyzed collaborative network maps and co-occurrence network maps.

RESULTS

We retrieved a total of 797 articles. Regarding the volume of publications, the total number of annual publications showed a fluctuating but overall increasing trend. Evidence-based Complementary and Alternative Medicine (21 articles) was the most productive journal, and Pain (225 articles) was the most cited journal. The most productive author was Qin W (16 articles), and the most co-cited author was Hui KKS (111). The most prolific institution and country were Massachusetts General Hospital (34 articles) and USA (212 articles). "Pain" was the top-ranked for keyword frequency and centrality. "Functional connectivity" was the frontier hotspot for 2018-2021.

CONCLUSION

First, fMRI researches on acupuncture analgesia involved several countries (regions) and institutions, mainly located in the USA, China and Korea, and most of them were universities. In addition, the USA was a major contributor in this field. Second, in terms of disciplinary distribution, the literatures were mainly from clinical neurology, neuroscience, and radiology nuclear medicine medical imaging. Third, the keyword co-occurrence analysis showed that the hot keywords included pain, fMRI, and lower back pain. Fourth, through keyword clustering analysis, the hot disease was found to be lower back pain, and the hot contents were acupuncture specificity and frequency specificity. Fifth, a timeline analysis of the references identified that chronic low back pain and specificity will remain a hot topic for future research.

A Narrative Review of Neuroimaging Studies in Acupuncture for Migraine

Acupuncture has been widely used as an alternative and complementary therapy for migraine. With the development of neuroimaging techniques, the central mechanism of acupuncture for migraine has gained increasing attention. This review aimed to analyze the study design and main findings of neuroimaging studies of acupuncture for migraine to provide the reference for future research. The original studies were collected and screened in three English databases (PubMed, Embase, and Cochrane Library) and four Chinese databases (Chinese National Knowledge Infrastructure, Chinese Biomedical Literature database, the Chongqing VIP database, and Wanfang database). As a result, a total of 28 articles were included. Functional magnetic resonance imaging was the most used neuroimaging technique to explore the cerebral activities of acupuncture for migraine. This review manifested that acupuncture could elicit cerebral responses on patients with migraine, different from sham acupuncture. The results indicated that the pain systems, including the medial pain pathway, lateral pain pathway, and descending pain modulatory system, participated in the modulation of the cerebral activities of migraine by acupuncture.

Neuroimaging Studies of Acupuncture on Low Back Pain: A Systematic Review

Objectives: This study was conducted in order to investigate the study design and main outcomes of acupuncture neuroimaging studies on low back pain (LBP). Methods: Neuroimaging studies of acupuncture on LBP were collected from three English databases such as PubMed and four Chinese databases such as China National Knowledge Infrastructure (CNKI) from inception to December 31, 2020. Study selection, data extraction, and assessment of risk of bias were performed independently by two investigators. The quality of studies was appraised with the Cochrane's risk of bias tools. Information on basic information, methodology, and brain imaging data were extracted. Results: The literature search returned 310 potentially eligible studies and 19 articles met inclusion criteria; 78.9% of studies chose manual acupuncture as the intervention, 89.5% of studies evaluated functional changes elicited by acupuncture, and 68.4% of studies used resting-state fMRI as imaging condition. The most frequently reported acupuncture-induced brain alterations of LBP patients were in the prefrontal cortex, insula, cerebellum, primary somatosensory cortex, and anterior cingulate cortex. There was a significant correlation between improved clinical outcomes and changes in the brain. Conclusions: The results suggested that improving abnormal structure and functional activities in the brain of the LBP patient is an important mechanism of acupuncture treatment for LBP. The brain regions involved in acupuncture analgesia for LBP were mainly located in the pain matrix, default mode network (DMN), salience network (SN), and descending pain modulatory system (DPMS). However, it was difficult to draw a generalized conclusion due to the heterogeneity of study designs. Further well-designed multimodal neuroimaging studies investigating the mechanism of acupuncture on LBP are warranted.

Modulatory Effects of Actual and Imagined Acupuncture on the Functional Connectivity of the Periaqueductal Gray and Ventral Tegmental Area

OBJECTIVE

Both acupuncture and guided imagery hold promise for treating pain. The mechanisms underlying these alternative interventions remain unclear. The reported study aimed to comparatively investigate the modulation effect of actual and imagined acupuncture on the functional connectivity of descending pain modulation system and reward network.

METHODS

Twenty-four healthy participants (mean [standard error], 25.21 [0.77] years of age; 66.67% female) completed a crossover study that included five sessions, a training session and four intervention sessions administered in randomized order. We investigated the modulation effect of real acupuncture, sham acupuncture, video-guided acupuncture imagery treatment (VGAIT) and VGAIT control on the resting-state functional connectivity (rsFC) of periaqueductal gray (PAG) and ventral tegmental area (VTA). These are key regions of the descending pain modulatory system and dopaminergic reward system, respectively.

RESULTS

Compared with sham acupuncture, real acupuncture produced decreased PAG-precuneus (Pcu) rsFC and increased VTA-amygdala/hippocampus rsFC. Heat pain threshold changes applied on the contralateral forearm were significantly associated with the decreased PAG-Pcu (r = 0.49, p = .016) and increased VTA-hippocampus rsFC (r = -0.77, p < .001). Compared with VGAIT control, VGAIT produced decreased PAG-paracentral lobule/posterior cingulate cortex/Pcu, middle cingulate cortex (MCC), and medial prefrontal cortex rsFC, and decreased VTA-caudate and MCC rsFC. Direct comparison between real acupuncture and VGAIT showed that VGAIT decreased rsFC in PAG-paracentral lobule/MCC, VTA-caudate/anterior cingulate cortex/nucleus accumbens, and VTA-MCC.

CONCLUSIONS

Results suggest that both actual and imagined acupuncture can modulate key regions in the descending pain modulatory system and reward networks, but through different pathways. Identification of different pain relief mechanisms may facilitate the development of new pain management methods.

Progress of Acupuncture Therapy in Diseases Based on Magnetic Resonance Image Studies: A Literature Review

The neural mechanisms of acupuncture are not well-understood. Over the past decades, an increasing number of studies have used MRI to investigate the response of the brain to acupuncture. The current review aims to provide an update on acupuncture therapy in disease. The PubMed, Embase, Web of Science, and Cochrane Library databases were searched from inception to January 31, 2021. Article selection and data extraction were conducted by two review authors. A total of 107 publications about MRI in acupuncture were included, the collective findings of which were as follows: (1) stroke and GB34 (Yanglingquan) are the most studied disease and acupoint. Related studies suggested that the mechanism of acupuncture treatment for stroke may associate with structural and functional plasticity, left and right hemispheres balance, and activation of brain areas related to movement and cognition. GB34 is mainly used in stroke and Parkinson's disease, which mainly activates brain response in the premotor cortex, the supplementary motor area, and the supramarginal gyrus; (2) resting-state functional MRI (rs-fMRI) and functional connectivity (FC) analysis are the most frequently used approaches; (3) estimates of efficacy and brain response to acupuncture depend on the type of sham acupuncture (SA) used for comparison. Brain processing after acupuncture differs between patients and health controls (HC) and occurs mainly in disorder-related areas. Factors that influence the effect of acupuncture include depth of needling, number and locations of acupoints, and deqi and expectation effect, each contributing to the brain response. While studies using MRI have increased understanding of the mechanism underlying the effects of acupuncture, there is scope for development in this field. Due to the small sample sizes, heterogeneous study designs, and analytical methods, the results were inconsistent. Further studies with larger sample sizes, careful experimental design, multimodal neuroimaging techniques, and standardized methods should be conducted to better explain the efficacy and specificity of acupuncture, and to prepare for accurate efficacy prediction in the future.

The anatomy of pain and suffering in the brain and its clinical implications

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Chronic pain, with a prevalence of 20-30 % is the major cause of human suffering worldwide, because effective, specific and safe therapies have yet to be developed. It is unevenly distributed among sexes, with women experiencing more pain and suffering. Chronic pain can be anatomically and phenomenologically dissected into three separable but interacting pathways, a lateral 'painfulness' pathway, a medial 'suffering' pathway and a descending pain inhibitory pathway. One may have pain(fullness) without suffering and suffering without pain(fullness). Pain sensation leads to suffering via a cognitive, emotional and autonomic processing, and is expressed as anger, fear, frustration, anxiety and depression. The medial pathway overlaps with the salience and stress networks, explaining that behavioural relevance or meaning determines the suffering associated with painfulness. Genetic and epigenetic influences trigger chronic neuroinflammatory changes which are involved in transitioning from acute to chronic pain. Based on the concept of the Bayesian brain, pain (and suffering) can be regarded as the consequence of an imbalance between the two ascending and the descending pain inhibitory pathways under control of the reward system. The therapeutic clinical implications of this simple pain model are obvious. After categorizing the working mechanisms of each of the available treatments (pain killers, psychopharmacology, psychotherapy, neuromodulation, psychosurgery, spinal cord stimulation) to 1 or more of the 3 pathways, a rational combination can be proposed of activating the descending pain inhibitory pathway in combination with inhibition of the medial and lateral pathway, so as to rebalance the pain (and suffering) pathways.

Different modulation effects of 1 Hz and 20 Hz transcutaneous auricular vagus nerve stimulation on the functional connectivity of the periaqueductal gray in patients with migraine

Background

A growing body of evidence suggests that transcutaneous auricular vagus nerve stimulation (taVNS) may relieve symptoms of migraineurs. Frequency is one of the key stimulation parameters. The aim of this study is to investigate the modulation effect of taVNS frequency on the descending pain modulation system (DPMS) in patients with migraine.

Methods

Twenty-four episodic migraineurs without aura (21 females) were recruited for the single-blind, crossover, functional magnetic resonance imaging (fMRI) study. Each participant attended two separate fMRI scan sessions, one for 1 Hz and another for 20 Hz taVNS, in a random order. Seed-based functional connectivity analysis was applied using the ventrolateral periaqueductal gray (PAG) as the region of interest.

Results

Compared with the pre-taVNS resting state, continuous 1 Hz taVNS (during) produced a significant increase in functional connectivity between the PAG and the bilateral middle cingulate cortex (MCC), right precuneus, left middle frontal gyrus (MFG), and left cuneus. Compared with 20 Hz taVNS, 1 Hz taVNS produced greater PAG connectivity increases with the MCC, right precuneus/posterior cingulate cortex, left insula, and anterior cingulate cortex (ACC). A significant negative correlation was observed between the number of migraine attacks in the previous 4 weeks and the PAG-MCC functional connectivity in the pre-taVNS resting-state before 1 Hz taVNS.

Conclusions

Our findings suggest that taVNS with different frequencies may produce different modulation effects on the descending pain modulation system, demonstrating the important role of stimulation frequency in taVNS treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03024-9.

Sex hormones regulate NHE1 functional expression and brain endothelial proteome to control paracellular integrity of the blood endothelial barrier

BACKGROUND

Sex hormones have been implicated in pH regulation of numerous physiological systems. One consistent factor of these studies is the sodium-hydrogen exchanger 1 (NHE1). NHE1 has been associated with pH homeostasis at epithelial barriers. Hormone fluctuations have been implicated in protection and risk for breaches in blood brain barrier (BBB)/blood endothelial barrier (BEB) integrity. Few studies, however, have investigated BBB/BEB integrity in neurological disorders in the context of sex-hormone regulation of pH homeostasis.

METHODS//RESULTS

Physiologically relevant concentrations of 17-β-estradiol (E2, 294 pM), progesterone (P, 100 nM), and testosterone (T,3.12 nM) were independently applied to cultured immortalized bEnd.3 brain endothelial cells to study the BEB. Individual gonadal hormones showed preferential effects on extracellular pH (E2), 14C-sucrose uptake (T), stimulated paracellular breaches (P) with dependence on functional NHE1 expression without impacting transendothelial resistance (TEER) or total protein expression. While total NHE1 expression was not changed as determined via whole cell lysate and subcellular fractionation experiment, biotinylation of NHE1 for surface membrane expression showed E2 reduced functional expression. Quantitative proteomic analysis revealed divergent effects of 17-β-estradiol and testosterone on changes in protein abundance in bEnd.3 endothelial cells as compared to untreated controls.

CONCLUSIONS

These data suggest that circulating levels of sex hormones may independently control BEB integrity by 1) regulating pH homeostasis through NHE1 functional expression and 2) modifying the endothelial proteome.

Scientific Knowledge Graph of Acupuncture for Migraine: A Bibliometric Analysis from 2000 to 2019

OBJECTIVE

This study aims to explore the trend and knowledge mapping of acupuncture for migraine through bibliometrics.

METHODS

It retrieved the literature on acupuncture for migraine in the Web of Science database from 2000 to 2019, and then resorted to CiteSpace to conduct bibliometric analysis to attain the knowledge mapping.

RESULTS

The total number of publications each year has increased year by year, and the average annual growth rate from 2000 to 2009 was 15.57%, while from 2010 to 2019 was 6.35%, with a faster growth rate from 2000 to 2009. According to the cluster analysis of institutions, authors, cited references, and keywords, 10, 7, 12, and 10 categories were gained from 2000 to 2019. The most productive countries, institutions, and authors are the USA and China, Technical University of Munich and Beijing University of Chinese Medicine, Linde K and Liang FR from 2000 to 2019, whose frequency is 119/103, 28/24, and 28/24, respectively. However, the most important of them are Canada, Sichuan University, and Witt CM. Owing to their highest centrality, they are 0.86, 0.54, and 0.27 separately. Moreover, cited references that contributed to the most co-citations are Linde K (2005), yet, the most vital cited reference is Karst M (2001). Keywords such as migraine, acupuncture, headache, pain, and randomized controlled trial are the most frequently used. However, needle acupuncture is the crucial keyword. In the cluster analysis of institutions, authors, cited references, and keywords from 2000 to 2019, the largest cluster categories are #0 migraine prophylaxis, #1 randomized controlled trial, #0 episodic migraine, and #0 topiramate treatment. Then, randomized controlled trials of acupuncture prevention and treatment of migraine are the most important research content in this field.

CONCLUSION

Through the bibliometric analysis of the research on acupuncture for migraine in the Web of Science database in the past 20 years, the trends and the Knowledge Graph of the country, institution, author, cited reference, and the keyword are acquired, which have an important guiding significance for quickly and accurately positioning the key information in the field.

Decreased Resting-State Functional Connectivity of Periaqueductal Gray in Temporal Lobe Epilepsy Comorbid With Migraine

Objective: Patients with temporal lobe epilepsy (TLE) are at high risk for having a comorbid condition of migraine, and these two common diseases are proposed to have some shared pathophysiological mechanisms. Our recent study indicated the dysfunction of periaqueductal gray (PAG), a key pain-modulating structure, contributes to the development of pain hypersensitivity and epileptogenesis in epilepsy. This study is to investigate the functional connectivity of PAG network in epilepsy comorbid with migraine.

Methods: Thirty-two patients with TLE, including 16 epilepsy patients without migraine (EwoM) and 16 epilepsy patients with comorbid migraine (EwM), and 14 matched healthy controls (HCs) were recruited and underwent resting functional magnetic resonance imaging (fMRI) scans to measure the resting-state functional connectivity (RsFC) of PAG network. The frequency and severity of migraine attacks were assessed using the Migraine Disability Assessment Questionnaire (MIDAS) and Visual Analog Scale/Score (VAS). In animal experiments, FluoroGold (FG), a retrograde tracing agent, was injected into PPN and its fluorescence detected in vlPAG to trace the neuronal projection from vlPAG to PPN. FG traced neuron number was used to evaluate the neural transmission activity of vlPAG-PPN pathway. The data were processed and analyzed using DPARSF and SPSS17.0 software. Based on the RsFC finding, the excitatory transmission of PAG and the associated brain structure was studied via retrograde tracing in combination with immunohistochemical labeling of excitatory neurons.

Results: Compared to HCs group, the RsFC between PAG and the left pedunculopontine nucleus (PPN), between PAG and the corpus callosum (CC), was decreased both in EwoM and EwM group, while the RsFC between PAG and the right PPN was increased only in EwoM group but not in EwM group. Compared to EwoM group, the RsFC between PAG and the right PPN was decreased in EwM group. Furthermore, the RsFC between PAG and PPN was negatively correlated with the frequency and severity of migraine attacks. In animal study, a seizure stimulation induced excitatory transmission from PAG to PPN was decreased in rats with chronic epilepsy as compared to that in normal control rats.

Conclusion: The comorbidity of epilepsy and migraine is associated with the decreased RsFC between PAG and PPN.

Revealing the Neural Mechanism Underlying the Effects of Acupuncture on Migraine: A Systematic Review

Background: Migraine is a chronic neurological disorder characterized by attacks of moderate or severe headache and various neurological symptoms. Migraine is typically treated by pharmacological or non-pharmacological therapies to relieve pain or prevent migraine attacks. Pharmacological therapies show limited efficacy in relieving headache and are often accompanied by adverse effects, while the benefits of acupuncture, a non-pharmacological therapy, have been well-documented in both the treatment and prevention of acute migraine attacks. However, the underlying mechanism of the effect of acupuncture on relieving migraine remains unclear. Recent advances in neuroimaging technology have offered new opportunities to explore the underlying neural mechanism of acupuncture in treating migraine. To pave the way for future research, this review provides an overview neuroimaging studies on the use of acupuncture for migraine in the last 10 years.

Methods: Using search terms about acupuncture, neuroimaging and migraine, we searched PubMed, Embase, Cochrane Central Register of Controlled Trials, and China National Knowledge Infrastructure from January 2009 to June 2020 for neuroimaging studies that examined the effect of acupuncture in migraine. All published randomized and non-randomized controlled neuroimaging studies were included. We summarized the proposed neural mechanism underlying acupuncture analgesia in acute migraine, and the proposed neural mechanism underlying the sustained effect of acupuncture in migraine prophylaxis.

Results: A total of 619 articles were retrieved. After removing reviews, meta-analyses, animal studies and etc., 15 articles were eligible and included in this review. The methods used were positron emission computed tomography (PET-CT; n = 2 studies), magnetic resonance spectroscopy (n = 1), and functional magnetic resonance imaging (fMRI; n = 12). The analyses used included the regional homogeneity (ReHo) method (n = 3), amplitude of low frequency (ALFF) method (n = 2), independent component analysis (ICA; n = 3), seed-based analysis (SBA; n = 1), both ICA and SBA (n = 1), Pearson's correlation to calculate functional connectivity (FC) between brain regions (n = 1), and a machine learning method (n = 1). Five studies focused on the instant effect of acupuncture, and the research objects were those with acute migraine (n = 2) and migraine in the interictal phase (n = 3). Ten studies focused on the lasting effect of acupuncture, and all the studies selected migraine patients in the interictal phase. This review included five task-based studies and 10 resting-state studies. None of the studies conducted a correlation analysis between functional brain changes and instant clinical efficacy. For studies that performed a correlation analysis between functional brain changes and sustained clinical efficacy, the prophylactic effect of acupuncture on migraine might be through regulation of the visual network, default mode network (DMN), sensory motor network, frontoparietal network (FPN), limbic system, and/or descending pain modulatory system (DPMS).

Conclusion: The neural mechanism underlying the immediate effect of acupuncture analgesia remains unclear, and the neural mechanism of sustained acupuncture treatment for migraine might be related to the regulation of pain-related brain networks. The experimental design of neuroimaging studies that examined the effect of acupuncture in migraine also have some shortcomings, and it is necessary to standardize and optimize the experimental design. Multi-center neuroimaging studies are needed to provide a better insight into the neural mechanism underlying the effect of acupuncture on migraine. Multi-modality neuroimaging studies that integrate multiple data analysis methods are required for cross-validation of the neuroimaging results. In addition, applying machine learning methods in neuroimaging studies can help to predict acupuncture efficacy and screen for migraineurs for whom acupuncture treatment would be suitable.

Neuroimaging in the Understanding of Acupuncture Analgesia: A Review of Acupuncture Neuroimaging Study Based on Experimental Pain Models

With the development of real-time and visualized neuroimaging techniques, the studies on the central mechanism of acupuncture analgesia gain increasing attention. The experimental pain models have been widely used in acupuncture-analgesia neuroimaging studies with quantitative and controlled advantages. This review aimed to analyze the study design and main findings of acupuncture neuroimaging studies to provide reference for future study. The original studies were collected and screened in English databases (PubMed, EMBASE, and Cochrane Library) and Chinese databases (Chinese Nation Knowledge Infrastructure, Chinese Biomedical Literature Database, the Chongqing VIP Database, and Wanfang Database). As a result, a total of 27 articles were included. Heat stimulation and electroacupuncture were the mostly used pain modeling method and acupuncture modality, respectively. The neuroimaging scanning process can be divided into two models and five subtypes. The anterior cingulate cortex and insula were the most commonly reported brain regions involved in acupuncture analgesia with experimental pain models.

The Altered Functional Connectivity With Pain Features Integration and Interaction in Migraine Without Aura

Introduction

Migraine without aura (MwoA) is a primary type of migraine, a common disabling disorder, and a disabling neurological condition. The headache is a complex experience, a common form of pain, in which multiple sensory information dimensions are combined to provide a unified conscious event. Migraine ictal have unique neuroimage biomarkers, but the brain is also affected during the inter-ictal phase. According to the current studies, a hypothesis was constructed that the altered integration of pain spatial and intensity information impacts headache intensity in the inter-ictal period.

Methods

In this study, we applied theory-based region-to-region functional connectivity (FC) analyses to compare the differences in resting-state FC between MwoA participants and healthy controls with the pain integration hypothesis. After the correlation matrices between FC edges and clinical symptoms were constructed, the moderating effect and simple slope tests were investigated to explain whether and how the dysfunction of pain features discrimination affects the clinical symptoms.

Results

Functional connectivity analyses showed significantly decreased FC edges between the left dorsolateral superior frontal gyrus (SFGdor) and left insula, and an increased FC edge between the left SFGdor and bilateral angular gyrus. The correlation matrix showed no significant correlation between significantly altered FC edge and headache duration, frequency, Zung self-rating anxiety scale, and Zung self-rating depression scale. Only one significantly altered edge in the MwoA condition was significantly correlated with headache intensity. Moderating Module 1 and 2 manifested the moderator variable (altered rs-FC edge) moderated the link between the normal edges and headache intensity.

Conclusion

The pain features integration processes in migraineurs vary from HCs, related to the clinical symptoms during a migraine attack. Moreover, the clinical symptoms will be affected by one or more discrimination modules. And the spatial or intensity discrimination modules have a higher impact when combined with another module on clinical symptoms than the single module.

Acupuncture vs. Pharmacological Prophylaxis of Migraine: A Systematic Review of Randomized Controlled Trials

Introduction: Migraine is a chronic paroxymal neurological disorder characterized by attacks of moderate to severe headache and reversible neurological and systemic symptoms. Treatment of migraine includes acute therapies, that aim to reduce the intensity of pain of each attack, and preventive therapies that should decrease the frequency of headache recurrence. The objective of this systematic review was to assess the efficacy and safety of acupuncture for the prophylaxis of episodic or chronic migraine in adult patients compared to pharmacological treatment.

Methods: We included randomized-controlled trials published in western languages that compared any treatment involving needle insertion (with or without manual or electrical stimulation) at acupuncture points, pain points or trigger points, with any pharmacological prophylaxis in adult (≥18 years) with chronic or episodic migraine with or without aura according to the criteria of the International Headache Society.

Results: Nine randomized trials were included encompassing 1,484 patients. At the end of intervention we found a small reduction in favor of acupuncture for the number of days with migraine per month: (SMD: −0.37; 95% CI −1.64 to −0.11), and for response rate (RR: 1.46; 95% CI 1.16–1.84). We found a moderate effect in the reduction of pain intensity in favor of acupuncture (SMD: −0.36; 95% CI −0.60 to −0.13), and a large reduction in favor of acupuncture in both the dropout rate due to any reason (RR 0.39; 95% CI 0.18 to 0.84) and the dropout rate due to adverse event (RR 0.26; 95% CI 0.09 to 0.74). Quality of evidence was moderate for all these primary outcomes. Results at longest follow-up confirmed these effects.

Conclusions: Based on moderate certainty of evidence, we conclude that acupuncture is mildly more effective and much safer than medication for the prophylaxis of migraine.