Migraine pathophysiology: anatomy of the trigeminovascular pathway and associated neurological symptoms, CSD, sensitization and modulation of pain

New Insights on Metabolic and Genetic Basis of Migraine: Novel Impact on Management and Therapeutical Approach

Migraine is a hereditary disease, usually one-sided, sometimes bilateral. It is characterized by moderate to severe pain, which worsens with physical activity and may be associated with nausea and vomiting, may be accompanied by photophobia and phonophobia. The disorder can occur at any time of the day and can last from 4 to 72 h, with and without aura. The pathogenic mechanism is unclear, but extensive preclinical and clinical studies are ongoing. According to electrophysiology and imaging studies, many brain areas are involved, such as cerebral cortex, thalamus, hypothalamus, and brainstem. The activation of the trigeminovascular system has a key role in the headache phase. There also appears to be a genetic basis behind the development of migraine. Numerous alterations have been identified, and in addition to the genetic cause, there is also a close association with the surrounding environment, as if on the one hand, the genetic alterations may be responsible for the onset of migraine, on the other, the environmental factors seem to be more strongly associated with exacerbations. This review is an analysis of neurophysiological mechanisms, neuropeptide activity, and genetic alterations that play a fundamental role in choosing the best therapeutic strategy. To date, the goal is to create a therapy that is as personalized as possible, and for this reason, steps forward have been made in the pharmacological field in order to identify new therapeutic strategies for both acute treatment and prophylaxis.

Real world considerations for newly approved CGRP receptor antagonists in migraine care

INTRODUCTION

Migraine is the leading cause of years lived with disability in people under 50 . Electrophysiological phenomena at the basis of prodromal and headache attack phases and of chronification processes involve calcitonin-gene related peptide (CGRP) as a fundamental player become a game changer of migraine pharmacotherapy.Areas covered: The purpose of the present review is to retrace fundamental stages of CGRP from its discovery to the role in migraine pathogenesis and therapy to underscore the change of paradigm offered by the newly approved small molecules to antagonize CGRP receptor, the gepants. In particular, the development of this new class is gone over from the initial synthesis of C-terminus truncated CGRP antagonists to the development of the first generation of gepants ending with Zavegepant that can be considered the third generation.Expert opinion: The history of CGRP in migraine draws the successful road to follow for key signaling pathways of modulation of nociceptive facilitation by diencephalic and brainstem nuclei, including dopaminergic neurotransmission, orexin A and the large-conductance calcium-activated potassium (BK_Ca) and ATP-sensitive potassium (K_ATP) channels also investigating the potential of essential oils and the role of polymorphisms. Real-world post marketing long-term data are needed for gepants.

The impacts of masks and disinfectants on migraine patients in the COVID-19 pandemic

Since the onset of the COVID-19 pandemic, the use of personal protective equipment (PPE) and disinfectants has become necessary to prevent transmission of the virus. However, the effects of such pandemic obligations on chronic diseases such as migraine have not been fully elucidated. We aimed to investigate the effects of the COVID-19 pandemic, as well as the use of masks and disinfectants, on migraine patients. A total of 310 migraine patients were included. Demographic data, migraine characteristics, and mask and disinfectant use were obtained through a face-to-face survey. Patients were grouped as worsening, stable, or improving according to pre-pandemic and pandemic migraine characteristics. Migraine worsening was found in 177 (57.1%) patients, stable course in 96 (31%) patients, and improvement in 37 (11.9%) patients. The use of scalp contact masks and double masks and daily mask duration were higher in the worsening group (p:0.005, p:0.005 and p:0.001). In addition, the frequency of personal disinfectant use was higher in this group (p:0.011). In regression analysis, mask type, daily mask duration, presence of allodynia, being a health worker, depression score, and odor were determined as independent risk factors for migraine worsening. We found a worsening of migraines in more than half of patients during the COVID-19 pandemic. We also demonstrated a relationship between migraine worsening and mask type, number of masks, and intensive disinfectant use. Migraine patients should be advised of optimal prevention methods based on individual social and working conditions rather than exaggerated preventative measures.

Coronavirus Disease 2019, Eye Pain, Headache, and Beyond

BACKGROUND

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), which causes Coronavirus Disease 2019 (COVID-19), emerged in December 2019 and became a devastating pandemic. Although its respiratory effects can be deadly and debilitating, it can lead to other systemic disorders, such as those causing eye pain and headache. This literature review aims to describe presentations of eye pain and headache in relation to COVID-19, with an emphasis on how these disorders help us to understand the pathophysiology of COVID-19.

EVIDENCE ACQUISITION

Literature was mined from the PubMed database using the key terms: "eye pain," "conjunctivitis," "episcleritis," "optic neuritis," "migraine," and "headache" in conjunction with "COVID-19" and "SARS-CoV-2." With the exception of general background pathology, articles that predated 2006 were excluded. Case reports, literature reviews, and meta-analyses were all included. Where SARS-CoV-2 research was deficient, pathology of other known viruses was considered. Reports of ocular manifestations of vision loss in the absence of eye pain were excluded. The primary search was conducted in June 2021.

RESULTS

The literature search led to a focused review of COVID-19 associated with conjunctivitis, episcleritis, scleritis, optic neuritis, and myelin oligodendrocyte glycoprotein-associated optic neuritis. Four distinct COVID-19-related headache phenotypes were identified and discussed.

CONCLUSIONS

Eye pain in the setting of COVID-19 presents as conjunctivitis, episcleritis, scleritis, or optic neuritis. These presentations add to a more complete picture of SARS-CoV-2 viral transmission and mechanism of host infection. Furthermore, eye pain during COVID-19 may provide evidence of hypersensitivity-type reactions, neurovirulence, and incitement of either novel or subclinical autoimmune processes. In addition, investigation of headaches associated with COVID-19 demonstrated 4 distinct phenotypes that follow third edition of the International Classification of Headache Disorders categories: headaches associated with personal protective equipment, migraine, tension-type headaches, and COVID-19-specific headache. Early identification of headache class could assist in predicting the clinical course of disease. Finally, investigation into the COVID-19-associated headache phenotype of those with a history of migraine may have broader implications, adding to a more general understanding of migraine pathology.

Neurofeedback Therapy for Sensory Over-Responsiveness-A Feasibility Study

Background: Difficulty in modulating multisensory input, specifically the sensory over-responsive (SOR) type, is linked to pain hypersensitivity and anxiety, impacting daily function and quality of life in children and adults. Reduced cortical activity recorded under resting state has been reported, suggestive of neuromodulation as a potential therapeutic modality. This feasibility study aimed to explore neurofeedback intervention in SOR. Methods: Healthy women with SOR (n = 10) underwent an experimental feasibility study comprising four measurement time points (T1—baseline; T2—preintervention; T3—postintervention; T4—follow-up). Outcome measures included resting-state EEG recording, in addition to behavioral assessments of life satisfaction, attaining functional goals, pain sensitivity, and anxiety. Intervention targeted the upregulation of alpha oscillatory power over ten sessions. Results: No changes were detected in all measures between T1 and T2. Exploring the changes in brain activity between T2 and T4 revealed power enhancement in delta, theta, beta, and gamma oscillatory bands, detected in the frontal region (p = 0.03−<0.001; Cohen’s d = 0.637−1.126) but not in alpha oscillations. Furthermore, a large effect was found in enhancing life satisfaction and goal attainment (Cohen’s d = 1.18; 1.04, respectively), and reduced pain sensitivity and anxiety trait (Cohen’s d = 0.70). Conclusion: This is the first study demonstrating the feasibility of neurofeedback intervention in SOR.

Effectiveness and acceptability of noninvasive brain and nerve stimulation techniques for migraine prophylaxis: a network meta-analysis of randomized controlled trials

BACKGROUND

Current pharmacologic prophylactic strategies for migraine have exhibited limited efficacy, with response rates as low as 40%-50%. In addition to the limited efficacy, the acceptability of those pharmacologic prophylactic strategies were unacceptable. Although noninvasive brain/nerve stimulation strategies may be effective, the evidence has been inconsistent. The aim of this network meta-analysis (NMA) was to compare strategies of noninvasive brain/nerve stimulation for migraine prophylaxis with respect to their effectiveness and acceptability.

METHODS

The PubMed, Embase, ScienceDirect, ProQuest, ClinicalTrials.gov , ClinicalKey, Cochrane CENTRAL, Web of Science, and ClinicalTrials.gov databases were systematically searched to date of June 4th, 2021 for randomized controlled trials (RCTs). Patients with diagnosis of migraine, either episodic migraine or chronic migraine, were included. All NMA procedures were conducted under the frequentist model.

RESULTS

Nineteen RCTs were included (N = 1493; mean age = 38.2 years; 82.0% women). We determined that the high frequency repetitive transcranial magnetic stimulation (rTMS) over C3 yielded the most decreased monthly migraine days among all the interventions [mean difference = - 8.70 days, 95% confidence intervals (95%CIs): - 14.45 to - 2.95 compared to sham/control groups]. Only alternating frequency (2/100 Hz) transcutaneous occipital nerve stimulation (tONS) over the Oz (RR = 0.36, 95%CIs: 0.16 to 0.82) yielded a significantly lower drop-out rate than the sham/control groups did.

CONCLUSIONS

The current study provided a new direction for the design of more methodologically robust and larger RCTs based on the findings of the potentially beneficial effect on migraine prophylaxis in participants with migraine by different noninvasive brain/nerve stimulation, especially the application of rTMS and tONS.

TRIAL REGISTRATION

CRD42021252638. The current study had been approval by the Institutional Review Board of the Tri-Service General Hospital, National Defense Medical Center (TSGHIRB No. B-109-29).

Noninvasive intracranial pressure monitoring in women with migraine

This cross-sectional study aimed to compare the waveform morphology through noninvasive intracranial pressure (ICP-NI) measurement between patients with migraine and controls, and to analyze the association with clinical variables. Twenty-nine women with migraine, age 32.4 (11.2) years and headache frequency of 12.6 (7.5) days per month and twenty-nine women without headache, age 32.1 (9.0) years, were evaluated. Pain intensity, migraine disability, allodynia, pain catastrophizing, central sensitization and depression were evaluated. The ICP-NI monitoring was performed by a valid method consisting of an extracranial deformation sensor positioned in the patients’ scalp, which allowed registration of intracranial pressure waveforms. Heart rate and blood pressure measurements were simultaneously recorded during 20 min in the supine position. The analyzed parameter was the P2/P1 ratio based on mean pulse per minute which P1 represents the percussion wave related to the arterial blood pression maximum and P2 the tidal wave, middle point between the P1 maximum and the dicrotic notch. There was no between-groups difference in the P2/P1 ratio (mean difference: 0.04, IC95%: -0.07 to 0.16, p = 0.352, F (1,1) = 0.881) adjusted by body mass index covariable. The Multiple Linear Regression showed non-statistical significance [F (5,44) = 1.104; p = 0.372; R² = 0.11)] between the P2/P1 ratio and body mass index, presence of migraine, central sensitization, pain catastrophizing and depression. We found no correlation (p > 0.05) between P2/P1 ratio and migraine frequency, migraine onset, pain intensity, pain intensity at day of examination, disability, allodynia. Migraine patients did not present alterations in the waveform morphology through ICP-NI compared to women without headache and no association with clinical variables was found.

Serum CGRP Changes following Ultrasound-Guided Bilateral Greater-Occipital-Nerve Block

Background: Calcitonin-gene-related peptide (CGRP) and CGRP receptors are expressed in trigeminal nerve cells, and treatments targeting CGRP are effective in migraines. For headaches that do not respond to pharmacological treatment, minimally invasive techniques such as greater-occipital-nerve block (GONB) can help relieve the pain and reduce the frequency of headaches. Our study assessed the efficacy of ultrasound-guided greater-occipital-nerve block (USgGONB) in chronic migraines (CM) and its relationship to serum CGRP levels. Methods: Forty chronic migraineurs who underwent bilateral USgGONB using 40 mg triamcinolone and 1 mL lidocaine were recruited and interictal serum CGRP samples were collected immediately before and one month after GONB. The clinical response was evaluated using headache diaries before and one month after USgGONB. The patient response was determined after USgGONB according to the reduction in headache days as a good responder (>50% reduction), poor responder (<50%) or non-responder. Results: Monthly headache days after GONB showed a significant reduction (median, 10 days; range, 8−14.7) compared to before the block (median, 18 days; range, 17−22; p < 0.001). Across all patients, interictal serum CGRP levels after USgGONB were significantly lower than before the block (median, 40 pg/mL (range, 25−60) vs. 145 pg/mL (range, 60−380) (p = 0.001). The pre-treatment interictal CGRP levels showed a significant difference (p = 0.003), as their levels in non-responders (median, 310 pg/mL; interquartile range, 262−350) were significantly higher than those seen in responders, whether poor responders (median, 135 pg/mL; interquartile range, 100−200 pg/mL) or good responders (median, 140 pg/mL; interquartile range, 80−150 pg/mL). Conclusion: the study showed the beneficial effect of USgGONB in chronic migraines that was associated with lowering interictal CGRP levels, implying a potential role for CGRP in the mechanism of action of GONB in CM, and the interictal CGRP level may be used as a predictor for the response to GONB.

Evaluating Plasma and Brain TRPV1 Channels in the Animal Model of Episodic and Chronic Migraine: The Possible Role of Somatosensory Cortex TRPV1 in Migraine Transformation

Background: Despite extensive research, the exact molecular mechanisms underlying migraine development and especially its progression and transformation from episodic into chronic is still unknown. Objectives: This study aimed to assess the role of somatosensory cortex and hippocampal transient receptor potential vanilloid 1 (TRPV1) in migraine in a rat model. Methods: This study was an intervention study. Adult male Wistar rats were divided into three groups, including sham, episodic migraine (EM), and chronic migraine (CM). The sham group received normal intraperitoneal (IP) saline injections every two days for 11 days, and the EM group received a single dose of trinitroglycerin (TNG) injection (IP; 10 mg/kg). For the CM group, TNG was administrated every two days (on days 3, 5, 7, 9, and 11; IP; 10 mg/kg). TRPV1 levels in plasma, somatosensory cortex, and hippocampus were detected with an enzyme-linked immunosorbent assay (ELISA) kit. Results: The findings showed that in both CM and EM groups the TRPV1 levels in plasma (P < 0.001 in both groups), somatosensory cortex (P < 0.05 and P < 0.001, respectively), and hippocampus (P < 0.01 in both groups) increased after migraine induction. Interestingly, in the somatosensory cortex, this TRPV1 elevation in the CM group was much greater than the EM group, and a significant difference was observed between the two groups (P < 0.05). Conclusions: Our results suggested that headache severity and frequency may enhance concomitant with the upregulation of somatosensory cortex TRPV1. This new achievement can help to develop new drug approaches to prevent CM.

The Association of Tanacetum parthenium and Salix alba Extracts Reduces Cortex Serotonin Turnover, in an Ex Vivo Experimental Model of Migraine

The mixture of water extracts from Tanacetum parthenium and Salix alba was studied in an ex vivo assessment of neurotoxicity constituted by isolated mouse cortex specimens challenged with K+ 60 mM Krebs–Ringer buffer (neurotoxicity stimulus). The effects of the mixture on lactate dehydrogenase (LDH), nitrite and serotonin levels were investigated. The phytochemical profile of the mixture was also evaluated. A docking approach was conducted to predict, albeit partially, the putative mechanism underlying the observed effects. The extracts displayed a good profile of polyphenolic compounds (22 chromatographic peaks detected), with caftaric acid and epicatechin being the prominent phenols. In isolated cortex, the association of T. parthenium and S. alba extracts was effective in reducing the K+ 60 mM-induced levels of LDH and nitrites, whereas the neurotoxicity stimulus-induced serotonin depletion was prevented by the treatment. Regarding the inhibition of serotonin catabolism, epicatechin (44.65 µg/mg) and caftaric acid (10.51 µg/mg) were putatively the main compounds involved in the inhibition of monoamineoxidase-A, which is known to play a master role in serotonin turnover. Collectively, the results of the present study point to the efficacy of the present extract mixture as an innovative pharmacological tool to prevent the onset of migraine.

Inhibition of Nociception in a Preclinical Episodic Migraine Model by Dietary Supplementation of Grape Seed Extract Involves Activation of Endocannabinoid Receptors

Migraine is associated with peripheral and central sensitization of the trigeminal system and dysfunction of descending pain modulation pathways. Recently, dietary inclusion of grape seed extract (GSE) was shown to inhibit mechanical nociception in a preclinical model of chronic temporomandibular joint disorder, a condition often comorbid with migraine, with the antinociceptive effect mediated, in part, by activation of 5-HT3/7 and GABAB receptors. This study further investigated the mechanisms by which GSE inhibits mechanical nociception in a preclinical model of episodic migraine. Hyperalgesic priming of female and male Sprague Dawley rats was induced by three consecutive daily two-hour episodes of restraint stress. Seven days after the final restraint stress, rats were exposed to pungent odors from an oil extract that contains the compound umbellulone, which stimulates CGRP release and induces migraine-like pain. Some animals received dietary supplementation of GSE in their drinking water beginning one week prior to restraint stress. Changes in mechanical sensitivity in the orofacial region and hindpaw were determined using von Frey filaments. To investigate the role of the endocannabinoid receptors in the effect of GSE, some animals were injected intracisternally with the CB1 antagonist AM 251 or the CB2 antagonist AM 630 prior to odor inhalation. Changes in CGRP expression in the spinal trigeminal nucleus (STN) in response to stress, odor and GSE supplementation were studied using immunohistochemistry. Exposure of stress-primed animals to the odor caused a significant increase in the average number of withdrawal responses to mechanical stimulation in both the orofacial region and hindpaw, and the effect was significantly suppressed by daily supplementation with GSE. The anti-nociceptive effect of GSE was inhibited by intracisternal administration of antagonists of CB1 and CB2 receptors. GSE supplementation inhibited odor-mediated stimulation of CGRP expression in the STN in sensitized animals. These results demonstrate that GSE supplementation inhibits trigeminal pain signaling in an injury-free model of migraine-like pain via activation of endocannabinoid receptors and repression of CGRP expression centrally. Hence, we propose that GSE may be beneficial as a complementary migraine therapeutic.

Cutaneous Allodynia in Migraine: A Narrative Review

Objective

In the present work, we conduct a narrative review of the most relevant literature on cutaneous allodynia (CA) in migraine.

Background

CA is regarded as the perception of pain in response to non-noxious skin stimulation. The number of research studies relating to CA and migraine has increased strikingly over the last few decades. Therefore, the clinician treating migraine patients must recognize this common symptom and have up-to-date knowledge of its importance from the pathophysiological, diagnostic, prognostic and therapeutic point of view.

Methods

We performed a comprehensive narrative review to analyze existing literature regarding CA in migraine, with a special focus on epidemiology, pathophysiology, assessment methods, risk for chronification, diagnosis and management. PubMed and the Cochrane databases were used for the literature search.

Results

The prevalence of CA in patients with migraine is approximately 60%. The mechanisms underlying CA in migraine are not completely clarified but include a sensitization phenomenon at different levels of the trigemino-talamo-cortical nociceptive pathway and dysfunction of brainstem and cortical areas that modulate thalamocortical inputs. The gold standard for the assessment of CA is quantitative sensory testing (QST), but the validated Allodynia 12-item questionnaire is preferred in clinical setting. The presence of CA is associated with an increased risk of migraine chronification and has therapeutic implications.

Conclusions

CA is a marker of central sensitization in patients with migraine that has been associated with an increased risk of chronification and may influence therapeutic decisions.

Altered effective connectivity in migraine patients during emotional stimuli: a multi-frequency magnetoencephalography study

BACKGROUND

Migraine is a common and disabling primary headache, which is associated with a wide range of psychiatric comorbidities. However, the mechanisms of emotion processing in migraine are not fully understood yet. The present study aimed to investigate the neural network during neutral, positive, and negative emotional stimuli in the migraine patients.

METHODS

A total of 24 migraine patients and 24 age- and sex-matching healthy controls were enrolled in this study. Neuromagnetic brain activity was recorded using a whole-head magnetoencephalography (MEG) system upon exposure to human facial expression stimuli. MEG data were analyzed in multi-frequency ranges from 1 to 100 Hz.

RESULTS

The migraine patients exhibited a significant enhancement in the effective connectivity from the prefrontal lobe to the temporal cortex during the negative emotional stimuli in the gamma frequency (30-90 Hz). Graph theory analysis revealed that the migraine patients had an increased degree and clustering coefficient of connectivity in the delta frequency range (1-4 Hz) upon exposure to positive emotional stimuli and an increased degree of connectivity in the delta frequency range (1-4 Hz) upon exposure to negative emotional stimuli. Clinical correlation analysis showed that the history, attack frequency, duration, and neuropsychological scales of the migraine patients had a negative correlation with the network parameters in certain frequency ranges.

CONCLUSIONS

The results suggested that the individuals with migraine showed deviant effective connectivity in viewing the human facial expressions in multi-frequencies. The prefrontal-temporal pathway might be related to the altered negative emotional modulation in migraine. These findings suggested that migraine might be characterized by more universal altered cerebral processing of negative stimuli. Since the significant result in this study was frequency-specific, more independent replicative studies are needed to confirm these results, and to elucidate the neurocircuitry underlying the association between migraine and emotional conditions.

Insulin sensitizes neural and vascular TRPV1 receptors in the trigeminovascular system

Background

Clinical observations suggest that hyperinsulinemia and insulin resistance can be associated with migraine headache. In the present study we examined the effect of insulin on transient receptor potential vanilloid 1 (TRPV1) receptor-dependent meningeal nociceptor functions in rats.

Methods

The effects of insulin on the TRPV1 receptor stimulation-induced release of calcitonin gene related peptide (CGRP) from trigeminal afferents and changes in meningeal blood flow were studied. Colocalization of the insulin receptor, the TRPV1 receptor and CGRP was also analyzed in trigeminal ganglion neurons.

Results

Insulin induced release of CGRP from meningeal afferents and consequent increases in dural blood flow through the activation of TRPV1 receptors of trigeminal afferents. Insulin sensitized both neural and vascular TRPV1 receptors making them more susceptible to the receptor agonist capsaicin. Immunohistochemistry revealed colocalization of the insulin receptor with the TRPV1 receptor and CGRP in a significant proportion of trigeminal ganglion neurons.

Conclusions

Insulin may activate or sensitize meningeal nociceptors that may lead to enhanced headache susceptibility in persons with increased plasma insulin concentration.

Migraine-relevant sex-dependent activation of mouse meningeal afferents by TRPM3 agonists

Background

Migraine is a common brain disorder that predominantly affects women. Migraine pain seems mediated by the activation of mechanosensitive channels in meningeal afferents. Given the role of transient receptor potential melastatin 3 (TRPM3) channels in mechanical activation, as well as hormonal regulation, these channels may play a role in the sex difference in migraine. Therefore, we investigated whether nociceptive firing induced by TRPM3 channel agonists in meningeal afferents was different between male and female mice. In addition, we assessed the relative contribution of mechanosensitive TRPM3 channels and that of mechanosensitive Piezo1 channels and transient receptor potential vanilloid 1 (TRPV1) channels to nociceptive firing relevant to migraine in both sexes.

Methods

Ten- to 13-week-old male and female wildtype (WT) C57BL/6 J mice were used. Nociceptive spikes were recorded directly from nerve terminals in the meninges in the hemiskull preparations.

Results

Selective agonists of TRPM3 channels profoundly activated peripheral trigeminal nerve fibres in mouse meninges. A sex difference was observed for nociceptive firing induced by either PregS or CIM0216, both agonists of TRPM3 channels, with the induced firing being particularly prominent for female mice. Application of Yoda1, an agonist of Piezo1 channels, or capsaicin activating TRPV1 channels, although also leading to increased nociceptive firing of meningeal fibres, did not reveal a sex difference. Cluster analyses of spike activities indicated a massive and long-lasting activation of TRPM3 channels with preferential induction of large-amplitude spikes in female mice. Additional spectral analysis revealed ​a dominant contribution of spiking activity in the α- and β-ranges following TRPM3 agonists in female mice.

Conclusions

Together, we revealed a specific mechanosensitive profile of nociceptive firing in females and suggest TRPM3 channels as a potential novel candidate for the generation of migraine pain, with particular relevance to females.

Decompression of the Greater Occipital Nerve for Occipital Neuralgia and Chronic Occipital Headache Caused by Entrapment of the Greater Occipital Nerve

BACKGROUND

 Chronic entrapment of the greater occipital nerve (GON) can not only manifest in typical stabbing pain of occipital neuralgia (ON) but also lead to continuous ache and pressure-like pain in the occipital and temporal areas. However, the effect of GON decompression on these symptoms has yet to be established. We report the follow-up results of GON decompression in typical cases of ON and chronic occipital headache due to GON entrapment (COHGONE).

METHODS

 A 1-year follow-up study of GON decompression was conducted on 11 patients with typical ON and 39 COHGONE patients with GON entrapment. The degree of pain reduction was analyzed using the numerical rating scale-11 (NRS-11) score and percent pain relief before and 1 year after surgery. A success was defined by at least a 50% reduction in pain measured via NRS-11 during the 12-month follow-up. To assess the degree of subjective satisfaction, a 10-point Likert scale was used. Postoperative outcome was also evaluated using the Barrow Neurological Institute (BNI) pain intensity score. The difference in GON decompression between the patients with typical ON and those with COHGONE was studied.

RESULTS

 GON decompression was successful in 43 of 50 patients (86.0%) and percent pain relief was 72.99 ± 25.53. Subjective improvement based on a 10-point Likert scale was 7.9 ± 2.42 and the BNI grade was 2.06 ± 1.04. It was effective in both the ON and COHGONE groups, but the success rate was higher in the ON group (90.9%) than in the COHGONE group (84.6%), showing statistically significant differences in the results based on average NRS-11 score, percent pain relief, subjective improvement, and BNI grades (p < 0.05, independent t-test).

CONCLUSION

 GON decompression is effective in chronic occipital headache and in ON symptoms induced by GON entrapment.

Evaluation of electrophysiological changes in migraine with visual aura

PURPOSE:

The purpose of this study was to evaluate the electrical responses in the retina and cortex of migraine patients with electrophysiological tests and compare with healthy controls.

MATERIALS AND METHODS:

This prospective study included 18 migraine patients with visual aura and 28 healthy controls. Pattern-reversal visual evoked potentials (VEP) and flash electroretinography (fERG) of migraine patients during the headache-free period were compared with healthy controls.

RESULTS:

There were statistically significant differences in VEP results: P100 and N75 amplitudes increased significantly (P = 0.025 and P = 0.007 respectively) and P100 latency decreased significantly in migraine patients (P = 0.022). Furthermore, fERG scotopic combined cone and rod amplitude increased significantly in migraine patients (P = 0.01).

CONCLUSION:

Migraine brain displays abnormal visual evoked responses in between migraine attacks. In migraine eye, scotopic cone and rod response increased. The results of this study support the hyperexcitability of the retina and cortex in patients with migraine.

Functional connectivity changes in complex migraine aura: beyond the visual network

BACKGROUND AND PURPOSE

Although the majority of migraine with aura (MwA) patients experience simple visual aura, a discrete percentage also report somatosensory, dysphasic or motor symptoms (the so-called complex auras). The wide aura clinical spectrum led to an investigation of whether the heterogeneity of the aura phenomenon could be produced by different neural correlates, suggesting an increased visual cortical excitability in complex MwA. The aim was to explore whether complex MwA patients are characterized by more pronounced connectivity changes of the visual network and whether functional abnormalities may extend beyond the visual network encompassing also the sensorimotor network in complex MwA patients compared to simple visual MwA patients.

METHODS

By using a resting-state functional magnetic resonance imaging approach, the resting-state functional connectivity (RS-Fc) of both visual and sensorimotor networks in 20 complex MwA patients was compared with 20 simple visual MwA patients and 20 migraine without aura patients.

RESULTS

Complex MwA patients showed a significantly higher RS-Fc of the left lingual gyrus, within the visual network, and of the right anterior insula, within the sensorimotor network, compared to both simple visual MwA and migraine without aura patients (p < 0.001). The abnormal right anterior insula RS-Fc was able to discriminate complex MwA patients from simple aura MwA patients as demonstrated by logistic regression analysis (area under the curve 0.83).

CONCLUSION

Our findings suggest that higher extrastriate RS-Fc might promote cortical spreading depression onset representing the neural correlate of simple visual aura that can propagate to sensorimotor regions if an increased insula RS-Fc coexists, leading to complex aura phenotypes.

Exploring the Potential Mechanism of Chuanxiong Rhizoma Treatment for Migraine Based on Systems Pharmacology

Migraine is a disease whose aetiology and mechanism are not yet clear. Chuanxiong Rhizoma (CR) is employed in traditional Chinese medicine (TCM) to treat various disorders. CR is effective for migraine, but its active compounds, drug targets, and exact molecular mechanism remain unclear. In this study, we used the method of systems pharmacology to address the above issues. We first established the drug-compound-target-disease (D-C-T-D) network and protein-protein interaction (PPI) network related to the treatment of migraine with CR and then established gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. The results suggest that the treatment process may be related to the regulation of inflammation and neural activity. The docking results also revealed that PTGS2 and TRPV1 could directly bind to the active compounds that could regulate them. In addition, we found that CR affected 11 targets that were more highly expressed in the liver or heart but were the lowest in the whole brain. It also expounds the description of CR channel tropism in TCM theory from these angles. These findings not only indicate that CR can be developed as a potential effective drug for the treatment of migraine but also demonstrate the application of systems pharmacology in the discovery of herbal-based disease therapies.

The Vitamin D Role in Preventing Primary Headache in Adult and Pediatric Population

Headache is among the main neurological disorders with a great impact on both adults and children. The diagnosis of primary headache and proper management is often delayed with a great impact on work productivity and overall quality of life. Chronic headache often requires prophylactic therapy to reduce the frequency and severity of the attacks and the use of abortive medications. Besides the use of several classes of drugs, another treatment modality is the use of Nutraceuticals. Some studies have suggested a possible role of vitamin D in headache prophylaxis. Indeed, vitamin D is involved in several pathways of brain development, neuroprotection and neurotransmission. Moreover, there is data suggesting a close relationship between primary headache and vitamin D deficiency, both in children and in adults. To date, a few studies have evaluated the effect of vitamin D on headaches. The aim of this review is to summarize the data collected on headache prophylaxis with vitamin D comparing the effects of vitamin D in pediatric and adult populations.

Determination of Current Flow Induced by Transcutaneous Electrical Nerve Stimulation for the Treatment of Migraine: Potential for Optimization

Introduction: Transcutaneous electrical nerve stimulation (TENS) for migraine involves the application of pulsatile stimulation through electrodes placed on the forehead to target the underlying trigeminal nerves. It is a simple, safe modality and has secured clinical approval in several markets including the European Union and the United States. Despite nearing almost 7 years of use (postclinical approval), the exact mechanism of action is not fully known. Guided by the need to stimulate the trigeminal nerves bilaterally, electrode dimensions are simply required to extend enough to cover the underlying nerves. The goal of this study is to examine induced current flow [magnitude and spatial distribution of electric field (EF)] and another driver of stimulation [activating function (AF)] due to TENS therapy for migraine for the first time. We further consider the effect of changing the electrode dimension and shape and propose a design modification to deliver optimal flow. Methods: We developed the first ultra-high-resolution finite element (FE) model of TENS for migraine incorporating the target supratrochlear (ST) and the supraorbital (SO) nerves. We first simulated the clinically approved V-shaped geometry. We then considered three additional designs: extended V-shaped, idealized pill-shaped, and finally an extended V-shaped but with greater contact spacing (extended V-shaped +CS). Results: Our findings revealed that the clinically approved electrode design delivered substantially higher mean current flow to the ST nerve in comparison with the SO nerves (Medial: 53% and Lateral: 194%). Consideration of an extended design (~10 mm longer and ~ 4 mm shorter) and a pill-like design had negligible impact on the induced current flow pattern. The extended V-shaped +CS montage delivered relatively comparable current flow to each of the three target nerves. The EF induced in the ST nerve was 49 and 141% higher in the Medial and Lateral SO nerve, respectively. When considering maximum induced values, the delivery of comparable stimulation was further apparent. Given the existing electrode design's established efficacy, our results imply that preferential targeting of the ST nerve is related to the mechanism of action. Additionally, if comparable targeting of all three nerves continues to hold promise, the extended V-shaped +CS montage presents an optimized configuration to explore in clinical studies.

Hypervigilance, Allostatic Load, and Migraine Prevention: Antibodies to CGRP or Receptor

Migraine involves brain hypersensitivity with episodic dysfunction triggered by behavioral or physiological stressors. During an acute migraine attack the trigeminal nerve is activated (peripheral sensitization). This leads to central sensitization with activation of the central pathways including the trigeminal nucleus caudalis, the trigemino-thalamic tract, and the thalamus. In episodic migraine the sensitization process ends with the individual act, but with chronic migraine central sensitization may continue interictally. Increased allostatic load, the consequence of chronic, repeated exposure to stressors, leads to central sensitization, lowering the threshold for future neuronal activation (hypervigilance). Ostensibly innocuous stressors are then sufficient to trigger an attack. Medications that reduce sensitization may help patients who are hypervigilant and help to balance allostatic load. Acute treatments and drugs for migraine prevention have traditionally been used to reduce attack duration and frequency. However, since many patients do not fully respond, an unmet treatment need remains. Calcitonin gene-related peptide (CGRP) is a vasoactive neuropeptide involved in nociception and in the sensitization of peripheral and central neurons of the trigeminovascular system, which is implicated in migraine pathophysiology. Elevated CGRP levels are associated with dysregulated signaling in the trigeminovascular system, leading to maladaptive responses to behavioral or physiological stressors. CGRP may, therefore, play a key role in the underlying pathophysiology of migraine. Increased understanding of the role of CGRP in migraine led to the development of small-molecule antagonists (gepants) and monoclonal antibodies (mAbs) that target either CGRP or the receptor (CGRP-R) to restore homeostasis, reducing the frequency, duration, and severity of attacks. In clinical trials, US Food and Drug Administration-approved anti-CGRP-R/CGRP mAbs were well tolerated and effective as preventive migraine treatments. Here, we explore the role of CGRP in migraine pathophysiology and the use of gepants or mAbs to suppress CGRP-R signaling via inhibition of the CGRP ligand or receptor.

New Insights and Methods for Recording and Imaging Spontaneous Spreading Depolarizations and Seizure-Like Events in Mouse Hippocampal Slices

Spreading depolarization (SD) is a sudden, large, and synchronous depolarization of principal cells which also involves interneurons and astrocytes. It is followed by depression of neuronal activity, and it slowly propagates across brain regions like cortex or hippocampus. SD is considered to be mechanistically relevant to migraine, epilepsy, and traumatic brain injury (TBI), but there are many questions about its basic neurophysiology and spread. Research into SD in hippocampus using slices is often used to gain insight and SD is usually triggered by a focal stimulus with or without an altered extracellular buffer. Here, we optimize an in vitro experimental model allowing us to record SD without focal stimulation, which we call spontaneous. This method uses only an altered extracellular buffer containing 0 mM Mg2+ and 5 mM K+ and makes it possible for simultaneous patch and extracellular recording in a submerged chamber plus intrinsic optical imaging in slices of either sex. We also add methods for quantification and show the quantified optical signal is much more complex than imaging alone would suggest. In brief, acute hippocampal slices were prepared with a chamber holding a submerged slice but with flow of artificial cerebrospinal fluid (aCSF) above and below, which we call interface-like. As soon as slices were placed in the chamber, aCSF with 0 Mg2+/5 K+ was used. Most mouse slices developed SD and did so in the first hour of 0 Mg2+/5 K+ aCSF exposure. In addition, prolonged bursts we call seizure-like events (SLEs) occurred, and the interactions between SD and SLEs suggest potentially important relationships. Differences between rats and mice in different chambers are described. Regarding optical imaging, SD originated in CA3 and the pattern of spread to CA1 and the dentate gyrus was similar in some ways to prior studies but also showed interesting differences. In summary, the methods are easy to use, provide new opportunities to study SD, new insights, and are inexpensive. They support previous suggestions that SD is diverse, and also suggest that participation by the dentate gyrus merits greater attention.

Role of herbal medicine for prevention and treatment of migraine

Migraine is a disabling neurovascular disease with unilateral or bilateral pulsatile headache, which intensively affects human health and quality of life due to high morbidity worldwide. Migraine is commonly accompanied by abnormal pain sensitization, neuroinflammatory response, and vasomotor dysfunction. Owing to the management dilemmas of migraine, there is an urgent need to develop effective and low-cost therapies. In recent years, herbal medicines as a promising strategy with analgesic activity and minor side effect, have been proposed for the prevention and treatment of migraine. Considering the lack of a review integrating experimental studies regarding the herbal treatment of migraine, this review systematically summarizes the important potential applications of herbal medicines in ameliorating migraine via multiple therapeutic targets and pathways, as well as provides a reference for further development of novel antimigraine drugs.

Tracking tDCS induced grey matter changes in episodic migraine: a randomized controlled trial

BACKGROUND

Occipital transcranial direct current stimulation (tDCS) is an effective and safe treatment for migraine attack prevention. Structural brain alterations have been found in migraineurs in regions related to pain modulation and perception, including occipital areas. However, whether these structural alterations can be dynamically modulated through tDCS treatment is understudied.

OBJECTIVE

To track longitudinally grey matter volume changes in occipital areas in episodic migraineurs during and up to five months after occipital tDCS treatment in a single-blind, and sham-controlled study.

METHODS

24 episodic migraineurs were randomized to either receive verum or sham occipital tDCS treatment for 28 days. To investigate dynamic grey matter volume changes patients underwent structural MRI at baseline (prior to treatment), 1.5 months and 5.5 months (after completion of treatment). 31 healthy controls were scanned with the same MRI protocol. Morphometry measures assessed rate of changes over time and between groups by means of tensor-based morphometry.

RESULTS

Before treatment, migraineurs reported 5.6 monthly migraine days on average. A cross-sectional analysis revealed grey matter volume increases in the left lingual gyrus in migraineurs compared to controls. Four weeks of tDCS application led to a reduction of 1.9 migraine days/month and was paralleled by grey matter volume decreases in the left lingual gyrus in the treatment group; its extent overlapping with that seen at baseline.

CONCLUSION

This study shows that migraineurs have increased grey matter volume in the lingual gyrus, which can be modified by tDCS. Tracking structural plasticity in migraineurs provides a potential neuroimaging biomarker for treatment monitoring.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03237754 . Registered 03 August 2017 - retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03237754 .

TRPA1-Mediated Src Family Kinases Activity Facilitates Cortical Spreading Depression Susceptibility and Trigeminovascular System Sensitization

Transient receptor potential ankyrin 1 (TRPA1) plays a role in migraine and is proposed as a promising target for migraine therapy. However, TRPA1-induced signaling in migraine pathogenesis is poorly understood. In this study, we explored the hypothesis that Src family kinases (SFKs) transmit TRPA1 signaling in regulating cortical spreading depression (CSD), calcitonin gene-related peptide (CGRP) release and neuroinflammation. CSD was monitored in mouse brain slices via intrinsic optical imaging, and in rats using electrophysiology. CGRP level and IL-1β gene expression in mouse trigeminal ganglia (TG) was detected using Enzyme-linked Immunosorbent Assay and Quantitative Polymerase Chain Reaction respectively. The results showed a SFKs activator, pYEEI (EPQY(PO3H2)EEEIPIYL), reversed the reduced cortical susceptibility to CSD by an anti-TRPA1 antibody in mouse brain slices. Additionally, the increased cytosolic phosphorylated SFKs at Y416 induced by CSD in rat ipsilateral cerebral cortices was attenuated by pretreatment of the anti-TRPA1 antibody perfused into contralateral ventricles. In mouse TG, a SFKs inhibitor, saracatinib, restored the CGRP release and IL-1β mRNA level increased by a TRPA1 activator, umbellulone. Moreover, umbellulone promoted SFKs phosphorylation, which was reduced by a PKA inhibitor, PKI (14-22) Amide. These data reveal a novel mechanism of migraine pathogenesis by which TRPA1 transmits signaling to SFKs via PKA facilitating CSD susceptibility and trigeminovascular system sensitization.

Network meta-analysis on efficacy and safety of different anti-CGRP monoclonal antibody regimens for prophylaxis and treatment of episodic migraine

BACKGROUND

Currently, studies have shown that anti-CGRP monoclonal antibodies are effective drugs for the prophylaxis and treatment of episodic migraine. Therefore, for the first time, we classified and concluded 10 treatment regimens according to the different doses, drugs, routes of administration, and courses of treatment, so as to provide a reference for further clinical studies.

METHODS

We studied relevant randomized controlled trials (RCTs) published before August 2020 on PubMed, Embase, Ovid MEDLINE, Web of Science, and the Cochrane Central Register of Controlled Trials.

RESULTS

Eleven RCTs involving 6397 patients were included in our analysis. Network meta-analysis results suggested that in the comparison of the average migraine days per month, Erenumab  (140 mg), Galcanezumab (120 mg, 240 mg), Fremanezumab (225 mg, 675 mg) were superior to placebo, Erenumab(7 mg), and the difference was statistically significant; Fremanezumab (225 mg, 675 mg) was superior to Erenumab (21 mg, 70 mg), and the difference was statistically significant; in the comparison of average medication days of acute migraine-specific drug per month, Erenumab (70 mg, 140 mg), Galcanezumab (120 mg, 240 mg), Fremanezumab (225 mg, 675 mg) was superior to placebo, and Erenumab (140 mg) and Galcanezumab (120 mg, 240 mg) were superior to Erenumab (70 mg), and the difference was statistically significant; there was no statistically significant difference in the average migraine days in the last month or in the medication days of acute migraine-specific drug.

CONCLUSION

Fremanezumab (225 mg) and Galcanezumab (120 mg) may be the best clinical protocol after a comprehensive assessment.

Distortion Product Otoacoustic Emissions and Their Suppression as Predictors of Peripheral Auditory Damage in Migraine: A Case-Control Study

Although several cochleo-vestibular symptoms are commonly associated with migraine, only a limited number of studies have been done in this regard. Some reported abnormalities in audiometry, auditory brainstem response and vestibular tests, considering these manifestations mainly related to central etiology. However, increasing evidence also suggests a peripheral involvement of the inner ear in migraine. The aim of this study was to investigate the peripheral auditory pathway in migraineurs using otoacoustic emissions (OAEs), to detect alteration of cochlear functioning and possible relationship with disease severity. Sixty-two migraineurs and sixty matched controls were enrolled in the study and underwent a routine neuro-otolaryngology examination; self-administered questionnaires were used to evaluate subjective perception of hearing disability. DPOAE and their suppression were lower in migraineurs compared to controls and significantly related to the disease duration. Altered DPOAE exposed migraineurs to the risk of affecting by migraine without aura, of presenting with ocular and/or auditory symptoms during attack and of using more painkillers. Concomitant dopaminergic symptoms and/or allodynia such as the acute non-consumption of triptans were significant determinants of decreased contralateral suppression of DPOAE among migraineurs. This potential subclinical cochlear impairment in migraine detected by OAEs may represent the earliest sign of sensorineural damage in these patients, providing a promising tool for the initial diagnosis and an opportunity to monitor disease course and treatment response over time.

Comparing Perimenstrual and Nonperimenstrual Migraine Attacks Using an e-Diary

BACKGROUND AND OBJECTIVES

Endogenous and exogenous female sex hormones are considered important contributors to migraine pathophysiology. Previous studies have cautiously suggested that perimenstrual migraine attacks have a longer duration and are associated with higher disability compared to nonperimenstrual attacks, but they showed conflicting results on acute therapy efficacy, pain intensity, and associated symptoms. We compared perimenstrual and nonperimenstrual migraine attack characteristics and assessed premenstrual syndrome (PMS) in women with migraine.

METHODS

Women with migraine were invited to complete a headache e-diary. Characteristics of perimenstrual attacks and nonperimenstrual attacks were compared. The primary outcome was attack duration. Secondary outcomes were headache intensity, accompanying symptoms, acute medication intake, and pain coping. Mixed effects models were used to account for multiple attacks within patients. PMS was assessed in patients without hormonal contraceptives. Subgroup analyses were performed for women with menstrually related migraine (MRM) and nonmenstrually related migraine (non-MRM) and women with a natural menstrual cycle and women using hormonal contraceptives.

RESULTS

A representative group of 500 participants completed the e-diary for at least 1 month. Perimenstrual migraine attacks (n = 998) compared with nonperimenstrual attacks (n = 4097) were associated with longer duration (20.0 vs 16.1 hours, 95% confidence interval 0.2-0.4), higher recurrence risk (odds ratio [OR] 2.4 [2.0-2.9]), increased triptan intake (OR 1.2 [1.1-1.4]), higher headache intensity (OR 1.4 [1.2-1.7]), less pain coping (mean difference -0.2 [-0.3 to -0.1]), more pronounced photophobia (OR 1.3 [1.2-1.4]) and phonophobia (OR 1.2 [1.1-1.4]), and less aura (OR 0.8 [0.6-1.0]). In total, 396/500 women completed the diary for ≥3 consecutive menstrual cycles, of whom 56% (221/396) fulfilled MRM criteria. Differences in attack characteristics became more pronounced when focusing on women with MRM and women using hormonal contraceptives. Prevalence of PMS was not different for women with MRM compared to non-MRM (11% vs 15%).

DISCUSSION

The longer duration of perimenstrual migraine attacks in women (with MRM) is associated with higher recurrence risk and increased triptan use. This may increase the risk of medication overuse and emphasizes the need to develop female-specific prophylactic treatment.

SCFA Treatment Alleviates Pathological Signs of Migraine and Related Intestinal Alterations in a Mouse Model of NTG-Induced Migraine

Background: There is a growing realization that the gut–brain axis signaling is critical for maintaining the health and homeostasis of the Central Nervous System (CNS) and the intestinal environment. The role of Short-Chain Fatty Acids (SCFAs), such as Sodium Propionate (SP) and Sodium Butyrate (SB), has been reported to counteract inflammation activation in the central and Enteric Nervous System (ENS). Methods: In this study, we evaluated the role of the SCFAs in regulating the pathophysiology of migraine and correlated dysregulations in the gut environment in a mouse model of Nitroglycerine (NTG)-induced migraine. Results: We showed that, following behavioral tests evaluating pain and photophobia, the SP and SB treatments attenuated pain attacks provoked by NTG. Moreover, treatments with both SCFAs reduced histological damage in the trigeminal nerve nucleus and decreased the expression of proinflammatory mediators. Ileum evaluation following NTG injection reported that SCFA treatments importantly restored intestinal mucosa alterations, as well as the release of neurotransmitters in the ENS. Conclusions: Taken together, these results provide evidence that SCFAs exert powerful effects, preventing inflammation through the gut–brain axis, suggesting a new insight into the potential application of SCFAs as novel supportive therapies for migraine and correlated intestinal alterations.

Clinical correlates of hypothalamic functional changes in migraine patients

OBJECTIVE

To elucidate the hypothalamic involvement in episodic migraine and investigate the association between hypothalamic resting state functional connectivity changes and migraine patients' clinical characteristics and disease progression over the years.

METHODS

Ninety-one patients with episodic migraine and 73 controls underwent interictal resting state functional magnetic resonance imaging. Twenty-three patients and controls were re-examined after a median of 4.5 years. Hypothalamic resting state functional connectivity changes were investigated using a seed-based correlation approach.

RESULTS

At baseline, a decreased functional interaction between the hypothalamus and the parahippocampus, cerebellum, temporal, lingual and orbitofrontal gyrus was found in migraine patients versus controls. Increased resting state functional connectivity between the hypothalamus and bilateral orbitofrontal gyrus was demonstrated in migraine patients at follow-up versus baseline. Migraine patients also experienced decreased right hypothalamic resting state functional connectivity with ipsilateral lingual gyrus. A higher migraine attack frequency was associated with decreased hypothalamic-lingual gyrus resting state functional connectivity at baseline, while greater headache impact at follow-up correlated with decreased hypothalamic-orbitofrontal gyrus resting state functional connectivity at baseline. At follow-up, a lower frequency of migraine attacks was associated with higher hypothalamic-orbitofrontal gyrus resting state functional connectivity.

CONCLUSIONS

During the interictal phase, the hypothalamus modulates the activity of pain and visual processing areas in episodic migraine patients. The hypothalamic-cortical interplay changes dynamically over time according to patients' clinical features.

Prenatal oestrogen-testosterone balance as a risk factor of migraine in adults

BACKGROUND

Migraine is a common neurological disease with extremely debilitating, but fully reversible symptoms. Women suffer from migraine more often than men. It was assumed that fluctuation of oestrogen level during menstrual cycle is one of many factors responsible for more frequent migraine attacks. The second-to-fourth digit ratio (2D:4D) is considered as an indicator of prenatal sex steroids. Balance of prenatal androgens (testosterone) and oestrogen has been studied in numerous diseases that are affected by hormones. However, the relationship between migraine and the sex steroids balance in prenatal development is still unexplained. The aim of this paper is to provide an evidence of relationship between prenatal oestrogen and testosterone exposure following 2D:4D digit ratio, and migraine prevalence in adults.

METHODS

We examined a group of 151 adults (33 males, 118 females) with migraine and a control group of 111 adults (45 males, 66 females). 2D:4D digit ratio of both hands was measured using sliding Vernier calliper.

RESULTS

Significant differences were found in the right hand. Female migraineurs had lower value of 2D:4D ratio than the control group and the right 2D:4D was lower than left 2D:4D (Δ2D:4D), suggesting prenatal testosterone dominance. The opposite relationship was observed in males. Male migraineurs had higher value of 2D:4D ratio and Δ2D:4D was greater than the control group, suggesting prenatal oestrogen dominance.

CONCLUSIONS

Our results suggest that depending on sex, different proportion of prenatal sex steroids might be a risk factor of migraine in adults. Women with migraine were presumably exposed in prenatal life to higher testosterone levels relative to oestrogen, while men with migraine were probably exposed in prenatal life to higher levels of oestrogen relative to testosterone.

Hormonal influences in migraine - interactions of oestrogen, oxytocin and CGRP

Migraine is ranked as the second highest cause of disability worldwide and the first among women aged 15-49 years. Overall, the incidence of migraine is threefold higher among women than men, though the frequency and severity of attacks varies during puberty, the menstrual cycle, pregnancy, the postpartum period and menopause. Reproductive hormones are clearly a key influence in the susceptibility of women to migraine. A fall in plasma oestrogen levels can trigger attacks of migraine without aura, whereas higher oestrogen levels seem to be protective. The basis of these effects is unknown. In this Review, we discuss what is known about sex hormones and their receptors in migraine-related areas in the CNS and the peripheral trigeminovascular pathway. We consider the actions of oestrogen via its multiple receptor subtypes and the involvement of oxytocin, which has been shown to prevent migraine attacks. We also discuss possible interactions of these hormones with the calcitonin gene-related peptide (CGRP) system in light of the success of anti-CGRP treatments. We propose a simple model to explain the hormone withdrawal trigger in menstrual migraine, which could provide a foundation for improved management and therapy for hormone-related migraine in women.

Air Pollutant Particles, PM2.5, Exposure and Glaucoma in Patients with Diabetes: A National Population-Based Nested Case-Control Study

The global prevalence of diabetes mellitus (DM) has reached 20%. Air pollutants with a particle size of less than 2.5 μm (PM2.5) are a globally recognized risk factor for diabetes and glaucoma. We examined whether the risk of glaucoma would decrease or increase when patients with DM were exposed to different PM2.5 concentrations. Data were obtained from the National Health Insurance Research Database (NHIRD) of Taiwan and the Air Quality Monitoring Network between 2008 and 2013. This nested case-control study involved 197 DM patients with glaucoma and 788 DM patients without glaucoma. Cases and controls were matched (1:4) by gender, age (±5 years), and index date (±6 months), and their data were entered in a logistic regression model adjusted for gender, age, urbanization level, income level, and comorbidities. The odds ratio (OR) of glaucoma at PM2.5 exposure concentration in the fourth quartile (Q4) compared with in the first quartile (Q1) was 1.7 (95% CI: 1.084-2.764). For glaucoma risk, the OR was 1.013 (95% CI: 1.006-1.020) at a PM2.5 exposure concentration in Q1, 1.004 (95% CI: 1.001-1.007) in the third quartile (Q3), and 1.003 (95% CI: 1.001-1.004) in Q4. In the subgroup analysis of patients living in non-emerging towns and non-agricultural towns, the OR for glaucoma in Q4 compared with in Q1 was 2.1 (95% CI: 1.229-3.406) and 1.8 (95% CI: 1.091-2.803), respectively (p trend = 0.001 and 0.011). For patients without migraine, the OR for glaucoma was 1.7 (95% CI: 1.074-2.782; p = 0.006). These results demonstrate that, for patients with DM, PM2.5 increased the risk of glaucoma and PM2.5 was an independent risk factor for glaucoma in patients with DM.

The eye in migraine: a review of retinal imaging findings in migraine

Migraine is a common headache disorder with neurovascular involvement. Because eyecare practitioners are likely to encounter people with migraine in their everyday practice, it is important to understand how migraine might impact on ocular health. In this narrative review, we provide an update on the latest ophthalmic imaging evidence for retinal involvement in migraine, derived from studies of retinal structure and retinal vascular perfusion using spectral domain and swept source optical coherence tomography (OCT) and OCT angiography. Combined structural OCT evidence from a recent meta-analysis indicates subtle and non-specific thinning of the peripapillary retinal nerve fibre layer (RNFL) in people with migraine, whereas there is little consistent evidence for structural abnormalities of the macular region. Recent advances in OCT angiography technology have also provided an opportunity to visualise microstructural damage and vascular dysregulation in the eyes of people with migraine. However, given that OCT and OCT angiography studies have been exclusively cross-sectional, it is not possible to demonstrate the causal effect of migraine events. Furthermore, the lack of common methodology (different ophthalmic imaging devices and analysis algorithms), and very limited datasets (small samples, heterogenous migraine groups), lead to an inability to make strong conclusions regarding the nature of altered retinal structure and vascular perfusion in migraine. Nevertheless, we discuss the clinical implications of such observations for eyecare practitioners and provide practical advice for the monitoring and management of patients with a history of migraine.

Bergapten Attenuates Nitroglycerin-Induced Migraine Headaches through Inhibition of Oxidative Stress and Inflammatory Mediators

The present study intended to examine the effect of bergapten and possible mechanisms involved in the treatment of migraine-associated symptoms in the rat model. Five doses of nitroglycerin (10 mg/kg) were injected intraperitoneal to induce migraine headaches in rats with a one-day break between each dose. Treatment groups received nitroglycerin followed after 1 day by bergapten (50 or 100 mg/kg), saline (10 mL/kg), or sumatriptan (50 mg/kg) once daily for 10 days. Behavioral observations were analyzed 2 h after nitroglycerin injections and 1 h 40 min after treatment. The animals were sacrificed 24 h after the last treatment dose. Samples of trigeminal nucleus caudalis (TNC) and cerebral cortex were collected and analyzed for antioxidant activity and expression of inflammatory markers by immunohistochemistry and enzyme-linked immunosorbent assay. Our findings revealed that bergapten notably decreases headache by altering mechanical allodynia, thermal allodynia, light phobicity, and the number of head-scratching incidence in rats. In the cortex and TNC regions, antioxidant factors were restored, and lipid peroxidation was significantly reduced. Furthermore, bergapten decreased the expression of inflammatory markers, such as nuclear factor kappa B (NF-Kb) and tumor necrosis factor-alpha (TNF-α), as evidenced by immunohistochemistry and ELISA. These results suggest that bergapten exhibits headache-relieving activity, possibly mediated through antioxidant and anti-inflammatory pathways.

Acupuncture Modulation Effect on Pain Processing Patterns in Patients With Migraine Without Aura

Introduction

In this retrospective study, resting-state functional connectivity (FC) in patients with migraine was analyzed to identify potential pathological pain processing patterns and compared them to those in healthy controls (HCs). The FC patterns in patients between pre- and post-acupuncture sessions were also analyzed to determine how acupuncture affects neurological activity and pain perception during the migraine interictal period.

Methods

In total, 52 patients with migraine without aura (MwoA) and 60 HCs were recruited. Patients with migraine were given acupuncture treatment sessions for 4 weeks. As a primary observation, functional magnetic resonance images were obtained at the beginning and end of the sessions. HCs received no treatment and underwent one functional magnetic resonance imaging (fMRI) scan after enrollment. After the fMRI data were preprocessed, a region of interest (ROI)-to-ROI analysis was performed with predefined ROIs related to pain processing regions.

Results

The first analysis showed significantly different FCs between patients with MwoA and HCs [false discovery rate corrected p-value (p-FDR) < 0.05]. The FCs were found to be mainly between the cingulate gyrus (CG) and the insular gyrus, the CG and the inferior parietal lobule (IPL), the CG and the superior frontal gyrus, and the middle frontal gyrus and the IPL. The second analysis indicated that acupuncture treatment partly restored the different FCs found in the first analysis (p-FDR < 0.05). Furthermore, subgroup analysis found different brain activity patterns in headache-intensity restored condition and headache-frequency restored condition. Lastly, the correlation analysis suggested a potential correlation between FCs and clinical symptoms (p < 0.05).

Conclusion

This study suggests that pain processing is abnormal in migraine, with significantly abnormal FCs in the frontal, parietal, and limbic regions. This finding could be a typical pathological feature of migraine. Acupuncture has been identified to relieve headache symptoms in two ways: it restores the pain processing function and regulates pain perception.

Nonocular Influencing Factors for Primary Glaucoma: An Umbrella Review of Meta-Analysis

INTRODUCTION

Glaucoma is the main cause of irreversible blindness worldwide. Still, little is known about nonocular risk factors. We use an umbrella review to examine the meta-analytic evidence of the correlation between nonocular factors and glaucoma.

METHOD

We searched PubMed and Embase databases up to July 24, 2020. Eligible meta-analyses (MAs) included cohort, case-control, and randomized controlled study designs. Two authors independently extracted the data and evaluated the methodological quality of the MAs. AMSTAR 2 was used to assess the methodological quality of each included MA.

RESULTS

This umbrella review contains 22 MAs with 22 unique nonocular factors in total. We identified 11 factors that increase the risk of glaucoma: hyperlipidemia, nocturnal dip in blood pressure, infection with Helicobacter pylori, myopia, obstructive sleep apnea syndrome, corneal properties, diabetes, hypertension, hypothyroidism, migraine, and plasma homocysteine. We identified 3 factors that reduce the risk of glaucoma: dietary intake of vitamin A, dietary intake of vitamin C, and short-term statin use. We identified 8 factors that had no association with glaucoma: dietary intake of vitamin B, dietary intake of vitamin E, cigarette smoking, Alzheimer's disease, serum folic acid, serum vitamin B6, serum vitamin B12, and serum vitamin D.

CONCLUSIONS

In this umbrella review of MAs, evidence was found for associations of various nonocular factors with glaucoma to different degrees. However, risk factors were only mildly associated, suggesting low impact of systemic risk factors. Additional higher quality studies are needed to provide robust evidence.

Detecting Abnormal Neuronal Activity in a Chronic Migraine Model by Egr1-EGFP Transgenic Mice

Chronic migraine (CM) is a highly disabling neurological disorder characterized by recurrent headache accompanied by a variety of sensory and/or emotional symptoms. However, the mechanisms of migraine onset and its chronicity have not been elucidated. The present study was designed to search for brain regions and neurons that were abnormally activated by CM and might be related to its pathogenesis and different concomitant symptoms. CM models were established here by repeated intraperitoneal injection of nitroglycerin (NTG) every other day for 9 days to early growth response gene 1 (Egr1)-enhanced green fluorescent protein (EGFP) transgenic mice, which allowed monitoring of neuronal activities in the whole brain. CM-related behaviors were recorded through head grooming test and light aversion assay. Elevation of Egr1 expression signals was detected in trigeminal nucleus caudalis (TNC), primary somatosensory cortex (SSp), lateral amygdala nucleus (LA), primary visual area (VISp), and temporal association areas (TEa) 2 h after the last injection of NTG by immunofluorescence and digital slice scanning technology. Meanwhile, no change of Egr1 expression was found in auditory areas (AUD), CA1, ectorhinal area (ECT), piriform (PIR), and anterior cingulate area (ACC). Furthermore, with the strongest support by evidence-based medicine among the current limited oral treatments of CM, topiramate was administrated every day for 11 days from 2 days before the first NTG injection. The results showed that topiramate partially improved the photophobia behavior of CM models in the short-term with gradually weakened efficacy as the course of the disease prolonged. Meanwhile, NTG-induced increase in Egr1 expression was completely reversed in TNC, SSp, and VISp and partially reduced in LA and TEa by topiramate at the same time point mentioned above. In conclusion, the current results suggested that the abnormal hyperactivities in TNC, SSp and VISp were associated with the pathogenesis of CM.

Chronic Migraine Pathophysiology and Treatment: A Review of Current Perspectives

Chronic migraine is a disabling neurological disorder that imposes a considerable burden on individual and socioeconomic outcomes. Chronic migraine is defined as headaches occurring on at least 15 days per month with at least eight of these fulfilling the criteria for migraine. Chronic migraine typically evolves from episodic migraine as a result of increasing attack frequency and/or several other risk factors that have been implicated with migraine chronification. Despite this evolution, chronic migraine likely develops into its own distinct clinical entity, with unique features and pathophysiology separating it from episodic migraine. Furthermore, chronic migraine is characterized with higher disability and incidence of comorbidities in comparison to episodic migraine. While existing migraine studies primarily focus on episodic migraine, less is known about chronic migraine pathophysiology. Mounting evidence on aberrant alterations suggest that pronounced functional and structural brain changes, central sensitization and neuroinflammation may underlie chronic migraine mechanisms. Current treatment options for chronic migraine include risk factor modification, acute and prophylactic therapies, evidence-based treatments such as onabotulinumtoxinA, topiramate and newly approved calcitonin gene-related peptide or receptor targeted monoclonal antibodies. Unfortunately, treatments are still predominantly ineffective in aborting migraine attacks and decreasing intensity and frequency, and poor adherence and compliance with preventative medications remains a significant challenge. Novel emerging chronic migraine treatments such as neuromodulation offer promising therapeutic approaches that warrant further investigation. The aim of this narrative review is to provide an update of current knowledge and perspectives regarding chronic migraine background, pathophysiology, current and emerging treatment options with the intention of facilitating future research into this debilitating and largely indeterminant disorder.

Intra-arterial injection of lidocaine into middle meningeal artery to treat intractable headaches and severe migraine

BACKGROUND AND PURPOSE

We report the results of intra-arterial injection of lidocaine in the middle meningeal artery in patients with intractable headache or status migrainosus.

METHODS

We treated four patients with intra-arterial lidocaine (2 mg/ml) in doses up to 50 mg in each middle meningeal artery via a microcatheter bilaterally (except in one patient). In two patients with intractable headache, the daily maximum intensity of headache (graded by 11-point numeric rating scale) was recorded for 7 days postprocedure. In two patients with status migrainosus, migraine-related disability 3 months prior and after treatment using MIDAS (Migraine Disability Assessment) questionnaire was recorded.

RESULTS

Intra-arterial lidocaine reduced the headache intensity from 8/10 and 10/10 to 0/10 in the two patients with intractable headaches for 2 days (day 0 and day 1) postprocedure. Despite recurrence of headache on day 2, the intensity was less than preprocedure intensity up to the last day recorded (by 3 and 2 points on day 7). In the two patients with status migrainosus, there was immediate reduction in headache intensity following intra-arterial lidocaine. The post treatment 3-month MIDAS score was lower in both patients compared with pretreatment 3-month score; 3 versus 30 and 55 versus 90. Severe disability preprocedure by MIDAS was reduced to little or no disability postprocedure in one patient.

CONCLUSIONS

Intra-arterial lidocaine resulted in amelioration of headache in patients with intractable headache and those with status migrainosus with improvement lasting longer than the short half-life of lidocaine possibly related to central desensitization.

Associations between diet quality, DASH and Mediterranean dietary patterns and migraine characteristics

This study was conducted to describe the dietary patterns and diet quality and to examine the correlation between diet quality, dietary patterns (Mediterranean or DASH) and migraine attributes.

Individuals between the ages of 18-64 who applied to the headache outpatient clinic and were diagnosed with episodic migraine were evaluated by a neurologist. Healthy Eating Index-2010 was used to determine the diet quality. Dietary Approaches to Stop Hypertension compliance scale and Mediterranean Diet Adherence Screener were used to describe the dietary patterns.

It was found that individuals with a low Mediterranean Diet Adherence Screener score had more severe disability and more severe and frequent attacks (p < 0.05). In addition, a significant negative correlation was found between Mediterranean Diet Adherence Screener score and attack severity (r = -0.733, p < 0.05). Individuals with a low Dietary Approaches to Stop Hypertension compliance scale score had more severe and frequent attacks (p < 0.05). There was a significant negative correlation between attack severity and Dietary Approaches to Stop Hypertension compliance scale scores (r = -0.700, p < 0.001). Individuals with poor diet quality had more severe migraine attacks compared to others (p < 0.05). A significant negative correlation was found between diet quality total score and attack severity (r = 0.458, p < 0.05). High diet quality scores and higher vegetables, fruits, legumes, and oil seeds subscores, DASH and Mediterranean dietary patterns were associated with lower migraine attack severity (p < 0.05).

A nutritional approach that adopts the Mediterranean diet or involves a good diet quality pattern can help alleviate the symptoms of individuals with migraine.

Oral cannabinoid preparations for the treatment of chronic migraine: a retrospective study

OBJECTIVE

To explore the effectiveness and safety of 3 oral cannabinoid preparations (FM2®, Bedrocan® and Bediol®) in the treatment of chronic migraine.

DESIGN

Retrospective, cohort study.

SUBJECTS

Patients with chronic migraine who received FM2®, Bedrocan® or Bediol® daily for the off-label treatment of their headache, up to 6 months.

METHODS

The number of migraine days per month, pain intensity, the number of acute medications taken per month, the number of days per month when the patient took at least one acute medication, and adverse events were recorded at baseline, 3 months, and 6 months after the start of treatment with oral cannabinoid preparations.

RESULTS

The number of migraine days didn't change significantly after the 3rd and the 6th month when compared to baseline (P = 0.1182). The pain intensity (P = 0.0004), the acute medication consumption (P = 0.0006) and the number of days per month in which patients took, at least, one acute medication, (P = 0.0004) significantly decreased when compared to the baseline. No significant differences were found between patients who were still taking a preventive treatment for chronic migraine and those who weren't (all P > 0.05). Different oral cannabinoid preparations displayed similar effectiveness (all P > 0.05). The AEs were mostly mild and occurred in the 43.75% of patients.

CONCLUSIONS

Oral cannabinoid preparations may have a role in reducing pain intensity and acute medication intake in patients with chronic migraine, but the magnitude of the effect seems modest; further studies are needed.

Persistent headache and low back pain after accidental dural puncture in the obstetric population: a prospective, observational, multicentre cohort study

Accidental dural puncture following epidural insertion can cause a post-dural headache that is defined by the International Headache Society as self-limiting. We aimed to confirm if accidental dural puncture could be associated with persistent headache and back pain when compared with matched control parturients. We performed a prospective multicentre cohort study evaluating the incidence of persistent headache following accidental dural puncture at nine UK obstetric units. Parturients who sustained an accidental dural puncture were matched with controls who had undergone an uneventful epidural insertion. Participants were followed-up at six-monthly intervals for 18 months. Primary outcome was the incidence of persistent headache at 18 months. Ninety parturients who had an accidental dural puncture were matched with 180 controls. The complete dataset for primary analysis was available for 256 (95%) participants. Incidence of persistent headache at 18 months was 58.4% (52/89) in the accidental puncture group and 17.4% (29/167) in the control group, odds ratio (95%CI) 18.4 (6.0-56.7), p < 0.001, after adjustment for past history of headache, Hospital Anxiety and Depression Scale (depression) and Hospital Anxiety and Depression Scale (anxiety) scores. Incidence of low back pain at 18 months was 48.3% (43/89) in the accidental puncture group and 17.4% (29/167) in the control group, odds ratio (95%CI) 4.14 (2.11-8.13), with adjustment. We have demonstrated that accidental dural puncture is associated with long-term morbidity including persistent headache in parturients. This challenges the current definition of post-dural puncture headache as a self-limiting condition and raises possible clinical, financial and medicolegal consequences.