Cortical mechanisms in migraine

Saudi clinical practice guidelines for the treatment and prevention of migraine headache

OBJECTIVE

To develop clinical practice guidelines based on evidence based medicine on the use of abortive and preventive therapies for managing migraine headaches. We formulated these guidelines to offer evidence-based recommendations to improve the knowledge of physicians, healthcare professionals, and policymakers in migraine headache management.

METHOD

A panel of 11 experts from different sectors in Saudi Arabia approved 26 questions on abortive and preventive therapies for migraines. To develop each question, we searched "PubMed" and "Cochrane Library" databases for recent relevant systematic reviews published between 2013 and 2024. We employed the Grading Recommendations, Assessment, Development, and Evaluation methodological approach to ensure the certainty of the collated evidence and to formulate the recommendations. The expert panel voted electronically on each recommendation, and a consensus was defined as >70% agreement.

RESULTS

We formulated a total of 26 recommendations. Of these, 14 are focused on abortive therapy for acute migraine attacks, whereas 12 are focused on the prevention of episodic or chronic migraines. These guidelines strongly recommend the use of paracetamol and ibuprofen as the first-line treatment for mild to moderate migraine. Furthermore, we concluded that propranolol should be considered as the first-line preventive intervention for migraine.

CONCLUSION

The Saudi clinical practice guidelines offer systematically validated recommendations of migraine headaches in adults. The recommendations are potentially beneficial for all healthcare professionals managing patients with migraine headaches.

An Overview of Prosopagnosia as a Symptom of Migraine: A Literature Review

PURPOSE OF REVIEW

Prosopagnosia is a neurological phenotype, characterized by the inability to recognize faces, typically resulting from damage or dysfunction in specific brain regions such as the fusiform gyrus. In contrast, migraine is a disease process, a complex neurological disorder with a range of symptoms including severe headache and visual disturbances.

RECENT FINDINGS

The brain regions involved in migraine and prosopagnosia are located in close proximity to each other, and perhaps as an unsurprising yet rarely reported result of this, there have been several cases of migraineurs, the majority presenting with aura, who manifested prosopagnosia as a symptom during an attack. While rarely reported, the fact that prosopagnosia can occasionally manifest during migraine episodes, particularly during the aura phase, emphasizes the importance of exploring the cortical processes involved in both conditions. This review discusses migraine and prosopagnosia in the context of comorbidity, explores and summarizes current and key historical knowledge on the reported occurrences of prosopagnosia manifesting as a symptom of migraine, and emphasizes the importance of reporting this phenomenon.

Peripherally acting anti-CGRP monoclonal antibodies attenuate cortical resting-state connectivity in migraine patients

BACKGROUND

In about half of migraine patients, anti-calcitonin gene-related peptide monoclonal antibodies reduce monthly migraine days by >50%. In these patients, this class of drugs may change cortical functions by decreasing nociceptive afferent barrage. This prospective study investigated functional connectivity changes in treatment responders after three-month treatment with galcanezumab.

METHODS

Resting-state functional magnetic resonance imaging data were acquired for patients with high-frequency episodic or chronic migraine (N = 36) before and after treatment. Of these, 19 patients were classified as treatment responders (≥50% reduction in monthly migraine days) and 17 were considered non-responders (<50% reduction). Functional connectivity across cortical regions was assessed using a region-of-interest (ROI)-to-ROI analysis approach.

RESULTS

At baseline, there were no significant differences between treatment responders and treatment non-responders. In the treatment responder group, reduced functional connectivity was observed after treatment between regions of the primary somatosensory and motor cortices, insula, and several occipital and temporo-occipital areas (within the visual network). In contrast, no such changes were seen in the non-responder group.

CONCLUSION

These findings suggest that even a relatively short period of reduced nociceptive signals may be sufficient to initiate a cortical recovery process in which its resting hyperexcitable mode shifts to a less excitable state.

Disrupted topologic efficiency of white matter structural connectome in migraine: a graph-based connectomics study

OBJECTIVE

To delineate the structural connectome alterations in patients with chronic migraine (CM), episodic migraine (EM), and healthy controls (HCs).

BACKGROUND

The pathogenesis of migraine chronification remains elusive, with structural brain network changes potentially playing a key role. However, there is a paucity of research employing graph theory analysis to explore changes in the whole brain structural networks in patients with CM and EM.

METHODS

The individual structural brain connectome of 60 patients with CM, 34 patients with EM, and 39 healthy control participants were constructed by using deterministic diffusion-tensor tractography. Graph metrics including global efficiency, characteristic path length, local efficiency, clustering coefficient, and small-world parameters were evaluated to describe the topologic organization of the white matter structural networks. Additionally, nodal clustering coefficient and efficiency were considered to assess the regional characteristics of the brain connectome. A graph-based statistic was used to assess brain network properties across the groups.

RESULTS

Graph theory analysis revealed significant disruptions in the structural brain networks of CM patients, characterized by reduced global efficiency, local efficiency, and increased characteristic path length compared to HCs. Additionally, CM patients exhibited significantly lower local efficiency than EM patients. Notably, the CM group demonstrated marked reductions in local clustering coefficient and nodal local efficiency in the frontal and temporal regions compared with the healthy control group and EM group. Nodal local efficiency can effectively distinguish CM from EM and HCs. Moreover, the disrupted topologic efficiency was significantly associated with attack frequency and MIDAS score in patients with migraine after Bonferroni correction.

CONCLUSION

Decreased structural connectivity in the frontal and temporal regions may serve as a neuroimaging marker for migraine chronification and disease progression, providing valuable insights into the pathophysiology of chronic migraine.

Potential of focal cortical dysplasia in migraine pathogenesis

Focal cortical dysplasias are abnormalities of the cerebral cortex associated with an elevated risk of neurological disturbances. Cortical spreading depolarization/depression is a correlate of migraine aura/headache and a trigger of migraine pain mechanisms. However, cortical spreading depolarization/depression is associated with cortical structural changes, which can be classified as transient focal cortical dysplasias. Migraine is reported to be associated with changes in various brain structures, including malformations and lesions in the cortex. Such malformations may be related to focal cortical dysplasias, which may play a role in migraine pathogenesis. Results obtained so far suggest that focal cortical dysplasias may belong to the causes and consequences of migraine. Certain focal cortical dysplasias may lower the threshold of cortical excitability and facilitate the action of migraine triggers. Migraine prevalence in epileptic patients is higher than in the general population, and focal cortical dysplasias are an established element of epilepsy pathogenesis. In this narrative/hypothesis review, we present mainly information on cortical structural changes in migraine, but studies on structural alterations in deep white matter and other brain regions are also presented. We develop the hypothesis that focal cortical dysplasias may be causally associated with migraine and link pathogeneses of migraine and epilepsy.

Differences in Neuropathology between Nitroglycerin-Induced Mouse Models of Episodic and Chronic Migraine

Multiple animal models of migraine have been used to develop new therapies. Understanding the transition from episodic (EM) to chronic migraine (CM) is crucial. We established models mimicking EM and CM pain and assessed neuropathological differences. EM and CM models were induced with single NTG or multiple injections over 9 days. Mechanical hypersensitivity was assessed. Immunofluorescence utilized c-Fos, NeuN, and Iba1. Proinflammatory and anti-inflammatory markers were analyzed. Neuropeptides (CGRP, VIP, PACAP, and substance P) were assessed. Mechanical thresholds were similar. Notable neuropathological distinctions were observed in Sp5C and ACC. ACC showed increased c-Fos and NeuN expression in CM (p < 0.001) and unchanged in EM. Sp5C had higher c-Fos and NeuN expression in EM (p < 0.001). Iba1 was upregulated in Sp5C of EM and ACC of CM (p < 0.001). Proinflammatory markers were strongly expressed in Sp5C of EM and ACC of CM. CGRP expression was elevated in both regions and was higher in CM. VIP exhibited higher levels in the Sp5C of EM and ACC of CM, whereas PACAP and substance P were expressed in the Sp5C in both models. Despite similar thresholds, distinctive neuropathological differences in Sp5C and ACC between EM and CM models suggest a role in the EM to CM transformation.

Visual Snow Syndrome in Patient with Migraine: Case Report and Literature Review

Visual snow syndrome (VSS) is a rarely diagnosed neurological phenomenon. It is a visual disorder characterised by the presence of numerous white, black, or translucent dots in the visual field, resembling the 'snow' of an analogue TV set experiencing reception interference. According to The International Classification of Headache Disorders, 3rd edition, visual snow is defined as a pattern of continuous small dots across the visual field lasting >3 months and accompanied by at least two of the following four additional symptoms: palinopsia, increased entoptic phenomena, photophobia, and nyctalopia. These complaints are not consistent with a typical migraine with visual aura and cannot be better explained by another disorder. The authors present the case of a 39-year-old woman who was diagnosed with VSS. The symptoms appeared after a migraine attack and had not alleviated. The patient reported a sensation of constant 'TV screen snow'. A neurological examination found no signs of focal damage to the nervous system. The results of the ophthalmological examination, MRI of the brain with contrast, MRI of the eye sockets, and EEG were normal. VSS is a phenomenon that is still not fully understood, different from migraine aura and associated with a number of additional symptoms. VSS is very difficult to treat. In this case, a lot of drugs were used without improvement. Further research must be conducted to determine the best treatment options for these patients.

Different vulnerability of fast and slow cortical oscillations to suppressive effect of spreading depolarization: state-dependent features potentially relevant to pathogenesis of migraine aura

BACKGROUND

Spreading depolarization (SD), underlying mechanism of migraine aura and potential activator of pain pathways, is known to elicit transient local silencing cortical activity. Sweeping across the cortex, the electrocorticographic depression is supposed to underlie spreading negative symptoms of migraine aura. Main information about the suppressive effect of SD on cortical oscillations was obtained in anesthetized animals while ictal recordings in conscious patients failed to detect EEG depression during migraine aura. Here, we investigate the suppressive effect of SD on spontaneous cortical activity in awake animals and examine whether the anesthesia modifies the SD effect.

METHODS

Spectral and spatiotemporal characteristics of spontaneous cortical activity following a single unilateral SD elicited by amygdala pinprick were analyzed in awake freely behaving rats and after induction of urethane anesthesia.

RESULTS

In wakefulness, SD transiently suppressed cortical oscillations in all frequency bands except delta. Slow delta activity did not decline its power during SD and even increased it afterwards; high-frequency gamma oscillations showed the strongest and longest depression under awake conditions. Unexpectedly, gamma power reduced not only during SD invasion the recording cortical sites but also when SD occupied distant subcortical/cortical areas. Contralateral cortex not invaded by SD also showed transient depression of gamma activity in awake animals. Introduction of general anesthesia modified the pattern of SD-induced depression: SD evoked the strongest cessation of slow delta activity, milder suppression of fast oscillations and no distant changes in gamma activity.

CONCLUSION

Slow and fast cortical oscillations differ in their vulnerability to SD influence, especially in wakefulness. In the conscious brain, SD produces stronger and spatially broader depression of fast cortical oscillations than slow ones. The frequency-specific effects of SD on cortical activity of awake brain may underlie some previously unexplained clinical features of migraine aura.

Two distinct neuroanatomical subtypes of migraine without aura revealed by heterogeneity through discriminative analysis

The neurobiological heterogeneity in migraine is poorly studied, resulting in conflicting neuroimaging findings. This study used a newly proposed method based on gray matter volumes (GMVs) to investigate objective neuroanatomical subtypes of migraine. Structural MRI and clinical measures of 31 migraine patients without aura and 33 matched healthy controls (HCs) were explored. Firstly, we investigated whether migraine patients exhibited higher interindividual variability than HCs in terms of GMVs. Then, heterogeneity through discriminative analysis (HYDRA) was applied to categorize migraine patients into distinct subtypes by regional volumetric measures of GMVs. Voxel-wise volume and clinical characteristics among different subtypes were also explored. Migraine patients without aura exhibited higher interindividual GMVs variability. Two distinct and reproducible neuroanatomical subtypes of migraine were revealed. These two subtypes exhibited opposite neuroanatomical aberrances compared to HCs. Subtype 1 showed widespread decreased GMVs, while Subtype 2 showed increased GMVs in limited regions. The total intracranial volume was significantly positively correlated with cognitive function in Subtype 2. Subtype 1 showed significantly longer illness duration and less cognitive scores compared to Subtype 2. The present study shows that migraine patients without aura have high structural heterogeneity and uncovers two distinct and robust neuroanatomical subtypes, which provide a possible explanation for conflicting neuroimaging findings.

Unveiling the Role of Contingent Negative Variation (CNV) in Migraine: A Review of Electrophysiological Studies in Adults and Children

Migraine has been considered a chronic neuronal-based pain disorder characterized by the presence of cortical hyperexcitability. The Contingent Negative Variation (CNV) is the most explored electrophysiological index in migraine. However, the findings show inconsistencies regarding its functional significance. To address this, we conducted a review in both adults and children with migraine without aura to gain a deeper understanding of it and to derive clinical implications. The literature search was conducted in the PubMed, SCOPUS and PsycINFO databases until September 2022m and 34 articles were retrieved and considered relevant for further analysis. The main results in adults showed higher CNV amplitudes (with no habituation) in migraine patients. Electrophysiological abnormalities, particularly focused on the early CNV subcomponent (eCNV), were especially prominent a few days before the onset of a migraine attack, normalizing during and after the attack. We also explored various modulatory factors, including pharmacological treatments-CNV amplitude was lower after the intake of drugs targeting neural hyperexcitability-and other factors such as psychological, hormonal or genetic/familial influences on CNV. Although similar patterns were found in children, the evidence is particularly scarce and less consistent, likely due to the brain's maturation process during childhood. As the first review exploring the relationship between CNV and migraine, this study supports the role of the CNV as a potential neural marker for migraine pathophysiology and the prediction of pain attacks. The importance of further exploring the relationship between this neurophysiological index and childhood migraine is critical for identifying potential therapeutic targets for managing migraine symptoms during its development.

Galcanezumab treatment changes visual related EEG connectivity patterns in migraine patients

BACKGROUND

Monoclonal antibodies against calcitonin gene-related peptides (CGRP) are innovative therapies for migraine treatment. Although they are clinically effective, how anti-CGRP treatment reduces migraine attacks still remains unclear.

OBJECTIVE

In this observational case-control study, we aimed to apply graph theory to EEG data from 20 migraine patients and 10 controls to investigate the effects of 3 months of galcanezumab on brain connectivity.

METHODS

We analyzed EEG rhythms during black-white pattern reversal stimulation with 0.5 cycle per degree spatial frequency before (T0) galcanezumab injection, as well as after 3 months (T2). EEG recordings made 1 hour after galcanezumab administration served as the control session (T1). Patients' connectivity patterns obtained at T0, T1 and T2 were compared with normal controls.

RESULTS

We found that galcanezumab increased network integration (with a 5% significance level corrected with the false discovery rate), changing the intensity of connections between the occipital through the frontal areas. At 3 months follow up, patients with persistent high headache intensity had a minor effect on the strength of connections (evaluated using Kendall's rank correlation test and p < 0.05).

CONCLUSIONS

The potent anti-nociceptive action that galcanezumab exerts at a peripheral level could restore cortical connections and possibly factors predisposing to attack onset.

Migraine in the context of chronic primary pain, chronic overlapping pain disorders, and functional somatic disorders: A narrative review

OBJECTIVE

To contextualize migraine as the most common primary headache disorder in relation to other chronic primary pain and non-pain functional somatic and mental conditions.

BACKGROUND

Migraine is increasingly understood as a sensory processing disorder within a broader spectrum of symptom disorders. This has implications for diagnosis and treatment.

METHOD

Narrative review based on a search of the literature of the last 15 years on the overlap of migraine with other symptom disorders.

RESULTS

Migraine as the prototypical primary headache disorder not only comprises many non-headache symptoms in itself, it also shows high comorbidity with other chronic pain and non-pain conditions (e.g., fibromyalgia syndrome, irritable bowel syndrome, functional non-epileptic seizures, depression, anxiety, and posttraumatic stress disorder). Such "symptom disorders" share several etiological factors (e.g., female preponderance, psychological vulnerability) and psychophysiological mechanisms (e.g., altered sensory processing, pain expectancy). These facts are acknowledged by several recent integrative conceptualizations such as chronic primary pain, chronic overlapping pain conditions, or functional somatic disorders. Accordingly, migraine management increasingly addresses the total symptom burden and individual contributors to symptom experience, and thus incorporates centrally acting pharmacological and non-pharmacological, that is, psychological and behavioral, treatment approaches.

CONCLUSIONS

Migraine and also other primary headache disorders should be seen as particular phenotypes within a broader spectrum of symptom perception and processing disorders that require integrative diagnostics and treatment. A harmonization of classifications and better interdisciplinary collaboration are desirable.

Effectiveness of gastrodin for migraine: A meta-analysis

Background

Gastrodia elata Blume (GEB), a traditional Chinese medicine, has been widely used to treat dizziness, numbness of limbs, and infantile convulsion, among other issues. Gastrodin is the main component of GEB. This meta-analysis aimed to evaluate the efficacy and safety of gastrodin in the treatment of migraine.

Methods

Ten electronic databases, namely the Cochrane Library, Embase, EBSCO, PubMed, Web of Science, CENTRAL, CNKI (China National Knowledge Infrastructure), CBM (Chinese Biomedicine Database), WanFang, and VIP (Chinese Scientific Journals Database), were searched for randomized controlled trials (RCTs) of gastrodin for migraine published before September 2021. The data were analyzed by RevMan 5.3 software and evaluated by GRADEpro.

Results

A total of 1,332 subjects were included in 16 RCTs. The meta-analysis showed that gastrodin was significantly effective in treating migraine (RR = 1.21, 95%CI = [1.17, 1.27]), reducing the pain degree (MD = −1.65, 95% CI = [−2.28, −1.02]), reducing the frequency of migraine attack (SMD = −2.77, 95% CI = [−3.92, −1.62]), shortening the duration of migraine attack (SMD = −1.64, 95% CI = [−2.35, −0.93]), and slowing average arterial cerebral blood flow velocity (SMD = −3.19, 95% CI = [−5.21, −1.17]), as well as being safe.

Conclusions

This systematic review revealed gastrodin is effective and safe in the treatment of migraine.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=197094, identifier: CRD42020197094.