Circadian Features of Cluster Headache and Migraine: A Systematic Review, Meta-analysis, and Genetic Analysis

Evening Chronotype Associates With Worse Physical and Mental Health and Headache-Related Disability Among Migraine Patients

Migraine has been linked to chronotype, but with mixed results. Here, we tested chronotype in association with physical and mental health and headache characteristics in a large database of migraine patients and controls. A sample of the UK Biobank (n = 360,081; 58.3% female, mean age: 56.38) was used. Data included self-reported chronotype, mental (neuroticism, depression, stress) and physical (body fat percentage, overall health rating) health factors, and migraine diagnosis based on ICD-10 G43 diagnosis from healthcare data. Morning type controls (Cmorning, n = 210,775), evening type controls (Cevening, n = 129,174), morning type migraine patients (Mmorning, n = 12,194), and evening type migraine patients (Mevening, n = 7938) were compared. Additionally, in a subsample of questionnaire-based migraine (n = 15,356), chronotype was tested in association with headache-related features. One-way ANOVA, Kruskal-Wallis test and chi-squared test were run in SPSS 28 with Bonferroni correction. Evening chronotype was more frequent among migraine patients with an OR = 1.06, 95% CI [1.03; 1.09] compared to controls (χ2 = 16.523, p < 0.001). The Mevening group showed the worst level of all mental and physical health variables, while the Cmorning group reported the best values. Migraine patients with morning or evening chronotype showed a highly similar headache symptom profile, but the Mevening subgroup expressed a higher disability (t = -3.965, p < 0.001). In conclusion, evening chronotype was associated with the worst physical and mental health status and the highest headache-related disability among migraine patients, suggesting a need for elevated medical attention on chronotype in migraine.

Limbic system abnormalities in episodic cluster headache: a 7T MRI multimodal study

BACKGROUND

Although the limbic system has long been thought to be involved in the pathophysiology of cluster headache, inconsistencies in imaging studies of episodic cluster headache (eCH) patients and limited understanding of the specific regions within the limbic system have prevented a full explanation of its involvement in the disease. Therefore, we performed multimodal imaging analysis using 7 T MRI with the aim of exploring structural-functional abnormalities in subregions of the limbic system and their relationship with clinical features.

METHODS

In this cross-sectional study, we employed 7T MRI to investigate structural (volumetric) and functional (fractional amplitude of low-frequency fluctuations (fALFF), regional homogeneity (ReHo)) alterations in limbic subregions (hypothalamus, thalamus, amygdala, hippocampus) among 69 in-bout but outside the attacks eCH patients and 63 healthy controls (HCs). Automated volumetry and resting-state functional MRI analyses were performed after adjusting for age, Generalized Anxiety Disorder scale, sex (and intracranial volume when evaluating volumetric measures). Then functional-structural coupling indices were computed to assess network-level relationships.

RESULTS

In eCH patients, volumes in right anterior inferior and right posterior of hypothalamus, left molecular_layer_hippocampal-head, left lateral-nucleus and left Central-nucleus on the headache side, as well as left tuberal inferior and left tuberal superior of hypothalamus, and right parasubiculum on the contralateral side were significantly altered compared with HCs (P < 0.05). Additionally, the volume of the right anterior inferior was positively correlated with the duration of last headache episode. After false discovery rate correction, widespread alterations in fALFF and ReHo values were observed among hypothalamic, thalamic, hippocampal, and amygdalar subregions, some of which correlated with clinical measures. Furthermore, the structure-function coupling indices in the right anterior inferior and the left lateral geniculate nucleus on the headache side differed significantly between eCH patients and HCs.

CONCLUSIONS

Our findings demonstrate that in-bout but outside the attacks eCH patients present anatomical and functional maladaptation of the limbic system. Moreover, the observed dissociation between localized abnormalities and largely preserved network coupling-except in the hypothalamus and thalamus-suggests that these two regions may be particularly susceptible to eCH-related dysfunction, while broader brain networks retain compensatory capacity in pathological states. These findings refine potential neuromodulation targets and highlight the value of ultrahigh-field imaging in eCH research.

Circadian attributes of neurological and psychiatric disorders as basis for their medication chronotherapy

This review focuses on (i) 24 h patterns in the symptom intensity of common neurologic and psychiatric disorders and (ii) medications prescribed for their management that have a recommended administration time or schedule, presumably to potentiate desired and minimize undesired effects and by definition qualify them as chronotherapies. Predictable-in-time patterning of symptoms is exhibited by many neurologic - headaches, multiple sclerosis, neurogenic orthostatic hypotension, neuropathic pain, Parkinson's disease, epileptic seizure, attention deficit hyperactivity, Alzheimer's disease - and psychiatric - eating, depressive, obsessive-compulsive, post-traumatic stress, anxiety, and panic - disorders, due either to circadian rhythms of disease pathophysiology or inadequacies of medication-delivery systems. Circadian disruption and circadian misalignment of the sleep-wake and other 24 h rhythms plus late chronotype are characteristic of many of these disorders, suggesting involvement in the mechanisms or consequence of their pathology or as an adverse effect of therapy, especially when administered at an inappropriate biological time. The Prescribers' Digital Reference, a compendium of all prescription medications approved for marketing in the US, reveals 65 of them are utilized to manage neurologic and psychiatric disorders by a recommended specified time-of-day or an asymmetrical interval or strength of dose schedule, presumably to optimize beneficial and minimize adverse effects, thereby qualifying them as chronotherapies. Overall, the contents of this review are intended to inform the development of future chronotherapies that incorporate state-of-the-art drug-delivery systems to improve management of neurologic and psychiatric disorders and associated circadian malalignment and disruption.

Dissecting the Circadian Clock and Toll-like Receptor Gene Alterations in Meniere's Disease and Vestibular Migraine

OBJECTIVE

To investigate alterations in the expression of circadian clock and Toll-like receptor (TLR) genes in peripheral blood (PB) leukocytes of patients with Meniere's disease (MD) and vestibular migraine (VM), and determine whether these gene expressions can differentiate MD from VM.

STUDY DESIGN

Observational prospective study.

SETTING

Tertiary academic medical center.

METHODS

PB leukocytes were collected from patients diagnosed with MD and VM during recent vertigo attacks, as well as from healthy controls. The expression levels of 9 circadian clock genes and 6 TLR genes were analyzed using real-time quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Sixty-nine participants were enrolled, including 28 patients with MD, 14 patients with VM, and 27 healthy controls. Both MD and VM groups showed lower expression of PER1 compared to the control group (P < .01). The VM group exhibited significantly lower expression of PER1, PER2, CRY1, BMAL1, CLOCK, and TIM compared to the MD group (all P < .001). The MD group had higher TLR9 expression than the control group, and elevated TLR4, TLR8, and TLR9 expression compared to the VM group (P < .05). In the VM group, patients with severe dizziness handicaps had significantly lower expression of PER2, CRY1, CRY2, and CK1ε compared to those with mild to moderate handicaps (P < .05).

CONCLUSION

This study identifies distinct alterations in the circadian clock and TLR gene expression in MD and VM, suggesting potential differences in the pathogenesis of these 2 vertiginous disorders and highlighting the possibility of these gene expressions as biomarkers for differentiation.

Genomics and pharmacogenomics of cluster headache: implications for personalized management? A systematic review

The role of genetic factors in cluster headache etiology, suggested by familial and twin studies, remains ill-defined, with the exact pathophysiological mechanisms still largely elusive. This systematic review aims to synthesize current knowledge on cluster headache genetics and explore its implications for personalized treatment and prediction of treatment response. Thus, we searched PubMed, Scopus, and the Cochrane Library databases and reference lists of identified research articles, meta-analyses, and reviews to identify relevant studies up to 10 July 2024. The quality of the evidence was assessed using Newcastle-Ottawa Scale for case control studies and NIH Quality Assessment tool for Observational Cohort and Cross-Sectional Studies. The protocol of this study was registered via the Open Science Framework ( https://osf.io/cd4s3 ). Fifty-one studies were selected for the qualitative synthesis: 34 candidate gene studies, 5 GWAS, 7 gene expression studies, 4 pharmacogenetic association studies, and 1 whole genome sequencing study. The bulk of genetic evidence in cluster headache underscores the involvement of genes associated with chronobiological regulation. The most studied gene in cluster headache is the HCRTR2 , which is expressed in the hypothalamus; however, findings across studies continue to be inconclusive. Recent GWAS have uncovered novel risk loci for cluster headache, marking a significant advancement for the field. Nevertheless, there remains a need to investigate various genes involved in specific mechanisms and pathways.

Co-morbid Indomethacin-Responsive Headaches in a Woman in Her Late 60s With Paroxysmal Hemicrania and Hypnic Headache: A Case Report

Paroxysmal hemicrania (PH) and hypnic headache (HH) are rare indomethacin-responsive headache syndromes. This case report details the new onset of both disorders in a woman in her late 60s. One headache type presented as severe pain centered on the right eyebrow, lasting 30 minutes, occurring more than 8 times daily, and associated with ipsilateral lacrimation and rhinorrhea. The second type was a right frontal severe pain, with onset at 4 a.m., occurring only during sleep, lasting 30 minutes, and with no associated factors. The patient's response to indomethacin for both headache types was confirmed through an unblinded ABAB study design: complete resolution of headaches during indomethacin use and recurrence upon discontinuation. This case highlights the rarity of co-morbid indomethacin-responsive headaches and underscores the diagnostic and therapeutic challenges associated with these conditions.

The impact of fear of attacks on pain-related disability in cluster headache: Insights from the fear avoidance model

OBJECTIVE

This study utilized the theoretical framework of the "fear avoidance model" (FAM) and investigated the role of fear of attack in pain-related disability. To this end, a measurement specific to cluster headache (CH) was used to investigate whether fear of attacks, alongside attack frequency, is a significant predictor of pain-related disability in CH.

BACKGROUND

Cluster headache substantially impacts daily functioning, yet empirical research exploring specific contributing factors is limited.

METHODS

A cross-sectional online survey was undertaken in patients with CH, gathering sociodemographic, clinical data, and responses on the Cluster Headache Scale and the Depression, Anxiety and Stress Scale.

RESULTS

Analysis of data from 640 patients (chronic CH: 287/640 [44.8%]; female: 264/640 [41.3%]; male: 373/640 [58.3%]; gender diverse: three of 640 [0.5%]; age range: 18-86 years; mean [standard deviation] Cluster Headache Scales subscale disability score: 36.9 [9.8]; out of 869 respondents) revealed that both attack frequency and fear of attacks significantly predicted pain-related disability (p < 0.001, percentage of variance explained: R2 = 0.24). More variance was explained by fear of attacks (R2 = 0.22) than by attack frequency (R2 = 0.02). This relationship remained significant even when controlling for depression and anxiety, which were also identified as independent predictors of pain-related disability (p < 0.001, R2 = 0.44).

CONCLUSION

This study emphasizes the relevance of psychological factors in CH-related disability. Fear of attacks was found to be an independent predictor, while attack frequency was of minor relevance. Empirical investigation of the FAM in CH could improve the understanding of the mechanisms underlying disability and contribute to the development of CH-specific interventions.

Headaches in Healthcare Workers: A Prospective Study of Precipitating and Maintenance Variables and Their Relationship with Burnout as a Post-COVID Syndrome

BACKGROUND

Headaches are a common symptom in healthcare workers (HCWs), mainly associated with high levels of stress. Different research has studied their incidence during the COVID-19 pandemic, most of them with correlational designs, and at the beginning of the pandemic and focused on the associated occupational variables.

AIMS

(1) To analyze the incidence of headaches in HCWs at the beginning of the COVID-19 pandemic and their maintenance six months later. (2) To explore the risk factors associated with their onset and maintenance, including sociodemographic, occupational, emotional symptomatology, and personality variables. (3) To propose a model to explain the chronification of stress in burnout, including the moderating role of chronic headaches.

METHODS

A prospective study (n = 259 HCWs) at three points in time during the COVID-19 pandemic, from the alarm state phase (T1: May-June 2020) to the post-pandemic stage (T3: April-July 2022), including an intermediate measure six months after T1 (T2). Descriptive analyses, Pearson's chi-square, Student's t, logistic regressions, and moderated mediation models were conducted using the Process package for SPSS. In addition to headaches, socio-demographic, occupational, emotional symptomatology, and personality variables were included.

RESULTS

At T1 the prevalence of headaches was 69.9%. At T2 the prevalence was 73.7%. Of these, 59.5% are T1-T2 sustained headaches. Headaches at T1 were associated with age (p = 0.010) (younger HCWs), professional category (p = 0.049) (nurses), service (p = 0.023) (ICU, COVID hospitalization), non-availability of PPE (p = 0.010), additional COVID-19 symptomatology (p < 0.001), and concern for contagion of family members (p < 0.001) (higher scores). In addition, HCWs with headaches had higher levels of stress (p = 0.001), anxiety (p = 0.001), depression (p = 0.041), and sleep disorders (p < 0.001). A subsequent logistic regression analysis showed that of the above variables, the presence of additional COVID-19 symptoms (p < 0.001) and depression (p = 0.010) were the predictor variables. With regard to the maintenance of headaches (T1-T2), anxiety (p = 0.035), stress (p = 0.001), and cognitive fusion (p = 0.013) were found to be the significant variables. The tested model proposes anxiety (T1) as antecedent, cognitive fusion (T2) as mediator, burnout (T3) as consequent, and chronic headaches (yes/no) as the moderating variable between anxiety and burnout (model 5). The model is significant (F = 19.84, p < 0.001) and contributes to the explanation of 36% of the variance of burnout. The relationships in the model are all statistically significant, and specifically chronic headaches contribute to a 6-fold increase in the likelihood of burnout.

CONCLUSIONS

The present research differentiates between precipitating and maintenance factors of headaches in HCWs. The former, more studied in previous research, are usually related to sociodemographic and occupational variables and levels of anxiety and stress. Maintenance factors, scarcely explored, are related to the maintenance of emotional symptomatology and the inability to manage intrusive thoughts (i.e., cognitive fusion). Of particular interest is that the presence of chronic headaches itself is capable of producing burnout as a post-COVID syndrome.

Circannual worsening in cluster headache correlates with daylight change

Cluster headache attacks typically occur with circadian rhythmicity and seasonal variability.In this article, we show that circannual rhythmicity of cluster headache attacks with its peak occurrence in spring and autumn could be explained by the rapidity in daylight alterations over the photoperiod, which is not constant but maximal at the time of equinoxes in spring. The peak of cluster attack occurrence at the equinoxes in spring and autumn coincides with greater leaps in day length, leading to interfere with synchronization of endogenous pacemaker systems. Interactions with the serotonergic system, also following circannual fluctuations are discussed.

Pre-cluster symptoms in a Taiwanese cohort of cluster headache: symptom profiles and clinical predictions

BACKGROUND

Pre-cluster symptoms (PCSs) are symptoms preceding cluster bouts and might have implications for the treatment of cluster headache (CH). This study investigated the prevalence of PCSs, and their utility in predicting upcoming bouts as well as the associations with therapeutic efficacy.

METHODS

We prospectively collected data from patients with CH. Each patient received a structured interview and completed questionnaire surveys during CH bouts. In sub-study 1, we cross-sectionally analyzed the prevalence, symptomatology, and predictability of upcoming bouts. Overall, 34 PCSs, divided into seven categories, were queried, including head and neck pain, cranial autonomic symptoms, restlessness, fatigue or mood changes, sleep alterations, constitutional symptoms, and generalized pain. In sub-study 2, we recorded the weekly frequency of CH attacks after the initiation of verapamil concurrently with a 14-day transitional therapy based on the patients' headache diary. A responder to verapamil was defined as a patient who have a reduction from baseline of at least 50% in the weekly frequency of CH attacks 4 weeks after the initiation of verapamil.

RESULTS

A total of 168 CH patients (women/men: 39/129) completed the study. In sub-study 1, we found 149 (88.7%) experienced PCSs, with a median of 24 (IQR 18 to 72) hours before the bouts. Up to 57.7% of patients with PCS reported that they could predict upcoming bouts. Among the seven categories of PCSs, head and neck pain was the most common (81.0%) and was associated with a higher predictability of upcoming bouts (odds ratio [OR] = 4.0; 95% confidence interval [CI] 1.7-9.6). In sub-study 2, we found two categories of PCSs were associated with the response to verapamil: sleep alteration (OR = 2.5 [95% CI = 1.3-4.8], p = 0.004) and ≥ 1 cranial autonomic symptoms (OR = 2.7 [95% CI = 1.4-5.1], p = 0.003).

CONCLUSION

PCSs were very common in CH and could be used to predict upcoming bouts. Different symptom categories of PCSs may have different clinical implications.

Acute and preventive medical treatment of cluster headache in Taiwan: A narrative review

Cluster headache (CH) is a debilitating neurological disorder characterized by severe, unilateral pain, and ipsilateral autonomic symptoms. Chronic CH is exceedingly rare in Taiwan, constituting approximately 1% of all CH cases. This narrative review provides an up-to-date overview of the acute and preventive treatment strategies for CH in Taiwan, focusing on currently available pharmacological options in the country. The treatment approach for CH in Taiwan involves a stepwise strategy. High-flow oxygen and triptan nasal sprays are the mainstays of acute treatment, providing rapid relief, and good tolerability. Transitional treatments, such as oral steroids and suboccipital steroid injections, serve as a crucial bridge between acute and long-term preventive therapies, offering temporary relief while minimizing side effects through a carefully limited duration. For preventive treatment, verapamil is the first-line option, with lithium and topiramate being the second-line alternatives. Among the calcitonin gene-related peptide (CGRP) monoclonal antibodies, galcanezumab has demonstrated efficacy in the prevention of episodic CH. Preventive treatments are personalized to individual patients, starting with low doses and close monitoring for adverse effects. Neuromodulatory therapies, such as noninvasive vagus nerve stimulation, show promise for chronic and refractory CH but have limited availability in Taiwan. In conclusion, despite the availability of various acute and preventive treatment options, unmet needs in the management of CH in Taiwan remain. In particular, increased awareness and education among healthcare professionals to improve the diagnosis and management of CH in Taiwan should be implemented.

Cluster headache: understandings of current knowledge and directions for whole process management

Cluster headache (CH) is a common primary headache that severely impacts patients' quality of life, characterized by recurrent, severe, unilateral headaches often centered around the eyes, temples, or forehead. Distinguishing CH from other headache disorders is challenging, and its pathogenesis remains unclear. Notably, patients with CH often experience high levels of depression and suicidal tendencies, necessitating increased clinical attention. This comprehensive assessment combines various reports and the latest scientific literature to evaluate the current state of CH research. It covers epidemiology, population characteristics, predisposing factors, and treatment strategies. Additionally, we provide strategic insights into the holistic management of CH, which involves continuous, individualized care throughout the prevention, treatment, and rehabilitation stages. Recent advances in the field have revealed new insights into the pathophysiology of CH. While these findings are still evolving, they offer a more detailed understanding of the neurobiological mechanisms underlying this disorder. This growing body of knowledge, alongside ongoing research efforts, promises to lead to the development of more targeted and effective treatments in the future.

Sleep Symptoms in Migraine

PURPOSE OF REVIEW

To review replicated and highlight novel studies of sleep in children and adults with episodic and chronic migraine.

RECENT FINDINGS

Attack-related sleep symptoms are most common in the prodrome and may represent early activation of the hypothalamus rather than migraine triggers. Interictally, patients with migraine report poor sleep quality and high rates of insomnia symptoms. Cognitive behavioral therapy for insomnia in adults and adolescents with chronic migraine and comorbid insomnia results in significant improvement on their headache burden. Thus far, objective studies report that migraine per se is a not associated with sleep apnea. At the present time, there is minimal evidence that migraine is under circadian influence. The current body of evidence suggests that the insomnia symptoms and poor sleep quality commonly reported by patients with migraine are not attack-related but occur interictally and are a marker of worsening disease. The development of clinical guidelines to approach sleep symptoms and expansion of CBT-I trials in those with episodic migraine would be clinically valuable.

The Role of Circadian Rhythm in Neurological Diseases: A Translational Perspective

Intrinsic biological clocks drive the circadian rhythm, which coordinates the physiological and pathophysiological processes in the body. Recently, a bidirectional relationship between circadian rhythms and several neurological diseases has been reported. Neurological diseases can lead to the disruption of circadian homeostasis, thereby increasing disease severity. Therefore, optimizing the current treatments through circadian-based approaches, including adjusted dosing, changing lifestyle, and targeted interventions, offer a promising opportunity for better clinical outcomes and precision medicine. In this review, we provide detailed implications of the circadian rhythm in neurological diseases through bench-to-bedside approaches. Furthermore, based on the unsatisfactory clinical outcomes, we critically discuss the potential of circadian-based interventions, which may encourage more studies in this discipline, with the hope of improving treatment efficacy in neurological diseases.

Recent advances in diagnosing, managing, and understanding the pathophysiology of cluster headache

Cluster headache, characterised by attacks of severe, recurrent, unilateral headache and ipsilateral cranial autonomic symptoms, remains a primary headache with an elusive pathophysiology. Recent advances have introduced effective treatments and broadened understanding of the clinical features of cluster headache. These features are similar in patients globally, but regional differences in prevalence and burden exist. International collaborations have led to identification of eight genetic loci associated with cluster headache. The pathophysiological mechanisms are still not fully understood but recent studies show that targeting the trigeminal autonomic reflex by neurostimulation, or targeting the neuropeptide calcitonin gene-related peptide (CGRP), might lessen the attack burden. The US Food and Drug Administration has approved galcanezumab, a monoclonal antibody targeting CGRP, as the first specific preventive treatment for episodic cluster headache. However, a preventive effect was not replicated in chronic cluster headache, and the European Medicines Agency did not approve galcanezumab, restricting its availability in Europe. Owing to the low prevalence of cluster headache, continued collaboration through multicentre clinical trials and data sharing will be imperative for further breakthroughs in understanding and management.

The location of pain in cluster headache: Data from the International Cluster Headache Questionnaire

OBJECTIVE

To identify the most common locations of cluster headache pain from an international, non-clinic-based survey of participants with cluster headache, and to compare these locations to other cluster headache features as well as to somatotopic maps of peripheral, brainstem, thalamic, and cortical areas.

BACKGROUND

Official criteria for cluster headache state pain in the orbital, supraorbital, and/or temporal areas, yet studies have noted pain extending beyond these locations, and the occipital nerve appears relevant, given the effectiveness of suboccipital corticosteroid injections and occipital nerve stimulation. Furthermore, cranial autonomic features vary between patients, and it is not clear if the trigeminovascular reflex is dermatome specific (e.g., do patients with maxillary or V2 division pain have more rhinorrhea?). Finally, functional imaging studies show early activation of the posterior hypothalamus in a cluster headache attack. However, the first somatosensory area to be sensitized is unclear; the first area can be hypothesized based on the complete map of pain locations.

METHODS

The International Cluster Headache Questionnaire was an internet-based cross-sectional survey that included a clickable pain map of the face. These data were compared to several other datasets: (1) a meta-analysis of 22 previous publications of pain location in cluster headache (consisting of 6074 patients); (2) four cephalic dermatome maps; (3) participants' survey responses for demographics, autonomic features, and effective medications; and (4) previously published somatotopic maps of the brainstem, thalamus, primary somatosensory cortex, and higher order somatosensory cortex.

RESULTS

One thousand five hundred eighty-nine participants completed the pain map portion of the survey, and the primary locations of pain across all respondents was the orbital, periorbital, and temporal areas with a secondary location in the lower occiput; these primary and secondary locations were consistent with our meta-analysis of 22 previous publications. Of the four cephalic dermatomes (V1, V2, V3, and a combination of C2-3), our study found that most respondents had pain in two or more dermatomes (range 85.7% to 88.7%, or 1361-1410 of 1589 respondents, across the four dermatome maps). Dermatomes did not correlate with their respective autonomic features or with medication effectiveness. The first area to be sensitized in the canonical somatosensory pathway is either a subcortical (brainstem or thalamus) or higher order somatosensory area (parietal ventral or secondary somatosensory cortices) because the primary somatosensory cortex (area 3b) and somatosensory area 1 have discontinuous face and occipital regions.

CONCLUSIONS

The primary pain locations in cluster headache are the orbital, supraorbital, and temporal areas, consistent with the official International Classification of Headache Disorders criteria. However, activation of the occiput in many participants suggests a role for the occipital nerve, and the pain locations suggest that somatosensory sensitization does not start in the primary somatosensory cortex.

Circadian functional changes of pain-processing brainstem nuclei and implications for cluster headache: A 7 Tesla imaging study

BACKGROUND

Pain thresholds and primary headaches, including cluster headache attacks, have circadian rhythmicity. Thus, they might share a common neuronal mechanism.

OBJECTIVE

This study aimed to elucidate how the modulation of nociceptive input in the brainstem changes from noon to midnight. Insights into the mechanism of these fluctuations could allow for new hypotheses about the pathophysiology of cluster headache.

METHODS

This repeated measure observational study was conducted at the University Hospital Zurich from December 2019 to November 2022. Healthy adults between 18 and 85 years of age were eligible. All participants were examined at noon and midnight. We tested the pain threshold on both sides of the foreheads with quantitative sensory testing, assessed tiredness levels, and obtained high-field (7 Tesla) and high-resolution functional magnetic resonance imaging (MRI) at each visit. Functional connectivity was assessed at the two visits by performing a region-of-interest analysis. We defined nuclei in the brainstem implicated in processing nociceptive input as well as the thalamus and suprachiasmatic nucleus as the region-of-interest.

RESULTS

Ten people were enrolled, and seven participants were included. First, we did not find statistically significant differences between noon and midnight of A-delta-mediated pain thresholds (median mechanical pain threshold at noon: left 9.2, right 9.2; at night: left 6.5, right 6.1). Second, after correction for a false discovery rate, we found changes in the mechanical pain sensitivity to have a statistically significant effect on changes in the functional connectivity between the left parabrachial nucleus and the suprachiasmatic nucleus (T = -40.79).

CONCLUSION

The MRI data analysis suggested that brain stem nuclei and the hypothalamus modulate A-delta-mediated pain perception; however, these changes in pain perception did not lead to statistically significantly differing pain thresholds between noon and midnight. Hence, our findings shed doubt on our hypothesis that the physiologic circadian rhythmicity of pain thresholds could drive the circadian rhythmicity of cluster headache attacks.

Orexins and primary headaches: an overview of the neurobiology and clinical impact

INTRODUCTION

Primary headaches, including migraines and cluster headaches, are highly prevalent disorders that significantly impact quality of life. Several factors suggest a key role for the hypothalamus, including neuroimaging studies, attack periodicity, and the presence of altered homeostatic regulation. The orexins are two neuropeptides synthesized almost exclusively in the lateral hypothalamus with widespread projections across the central nervous system. They are involved in an array of functions including homeostatic regulation and nociception, suggesting a potential role in primary headaches.

AREAS COVERED

This review summarizes current knowledge of the neurobiology of orexins, their involvement in sleep-wake regulation, nociception, and functions relevant to the associated symptomology of headache disorders. Preclinical reports of the antinociceptive effects of orexin-A in preclinical models are discussed, as well as clinical evidence for the potential involvement of the orexinergic system in headache.

EXPERT OPINION

Several lines of evidence support the targeted modulation of orexinergic signaling in primary headaches. Critically, orexins A and B, acting differentially via the orexin 1 and 2 receptors, respectively, demonstrate differential effects on trigeminal pain processing, indicating why dual-receptor antagonists failed to show clinical efficacy. The authors propose that orexin 1 receptor agonists or positive allosteric modulators should be the focus of future research.

Photophobia is associated with lower sleep quality in individuals with migraine: results from the American Registry for Migraine Research (ARMR)

BACKGROUND

Patients with migraine often have poor sleep quality between and during migraine attacks. Furthermore, extensive research has identified photophobia as the most common and most bothersome symptom in individuals with migraine, second only to headache. Seeking the comfort of darkness is a common strategy for managing pain during an attack and preventing its recurrence between episodes. Given the well-established effects of daily light exposure on circadian activity rhythms and sleep quality, this study aimed to investigate the relationship between photophobia symptoms and sleep quality in a cohort of patients with migraine.

METHODS

A cross-sectional observational study was conducted using existing data extracted from the American Registry for Migraine Research (ARMR). Participants with a migraine diagnosis who had completed the baseline questionnaires (Photosensitivity Assessment Questionnaire (PAQ), Generalized Anxiety Disorder-7 (GAD-7), Patient Health Questionnaire-2 (PHQ-2)), and selected questions of the ARMR Sleep questionnaire were included. Models were created to describe the relationship of photophobia and photophilia with various sleep facets, including sleep quality (SQ), sleep disturbance (SDis), sleep onset latency (SOL), sleep-related impairments (SRI), and insomnia. Each model was controlled for age, sex, headache frequency, anxiety, and depression.

RESULTS

A total of 852 patients meeting the inclusion criteria were included in the analysis (mean age (SD) = 49.8 (13.9), 86.6% (n = 738) female). Those with photophobia exhibited significantly poorer sleep quality compared to patients without photophobia (p < 0.001). Photophobia scores were associated with SQ (p < 0.001), SDis (p < 0.001), SOL (p = 0.011), SRI (p = 0.020), and insomnia (p = 0.005) after controlling for age, sex, headache frequency, depression, and anxiety, signifying that higher levels of photophobia were associated with worse sleep-related outcomes. Conversely, photophilia scores were associated with better sleep-related outcomes for SQ (p < 0.007), SOL (p = 0.010), and insomnia (p = 0.014).

CONCLUSION

Results suggest that photophobia is a significant predictor of poor sleep quality and sleep disturbances in migraine. These results underscore the necessity for comprehensive and systematic investigations into the intricate interplay between photophobia and sleep to enhance our understanding and develop tailored solutions for individuals with migraine.

CLOCK gene circannual expression in cluster headache

BACKGROUND

Cluster headache is a primary headache disorder characterized by bouts with circadian and circannual patterns. The CLOCK gene has a central role in regulating circadian rhythms. Here, we investigate the circannual CLOCK expression in a population of cluster headache patients in comparison to matched controls.

METHODS

Patients with cluster headache were sampled two to four times over at least one year, both in or outside bouts, one week after each solstice and equinox. The expression of CLOCK was measured by quantitative real-time polymerase chain reaction (RT-PCR) in the peripheral blood.

RESULTS

This study included 50 patients and 58 matched controls. Among the patient population, composed of 42/50 males (84%) with an average age of 44.6 years, 45/50 (90%) suffered from episodic cluster headache. Two to four samples were collected from each patient adding up to 161 samples, 36 (22.3%) of which were collected within a bout. CLOCK expression for cluster headache patients was considerably different from that of the control population in winter (p-value mean = 0.006283), spring (p-value mean = 0.000006) and summer (p-value mean = 0.000064), but not in autumn (p-value mean = 0.262272). For each season transition, the variations in CLOCK expression were more pronounced in the control group than in the cluster headache population. No statistically significant differences were found between bout and non-bout samples. No individual factors (age, sex, circadian chronotype, smoking and coffee habits or history of migraine) were related to CLOCK expression.

CONCLUSIONS

We observed that CLOCK expression in cluster headache patients fluctuates less throughout the year than in the control population. Bout activity and lifestyle factors do not seem to influence CLOCK expression.

Cluster Headache, SUNCT, and SUNA

OBJECTIVE

This article reviews the epidemiology, clinical features, differential diagnosis, pathophysiology, and management of three types of trigeminal autonomic cephalalgias: cluster headache (the most common), short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT), and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA).

LATEST DEVELOPMENTS

The first-line treatments for trigeminal autonomic cephalalgias have not changed in recent years: cluster headache is managed with oxygen, triptans, and verapamil, and SUNCT and SUNA are managed with lamotrigine. However, new successful clinical trials of high-dose prednisone, high-dose galcanezumab, and occipital nerve stimulation provide additional options for patients with cluster headache. Furthermore, new genetic and imaging tests in patients with cluster headache hold promise for a better understanding of its pathophysiology.

ESSENTIAL POINTS

The trigeminal autonomic cephalalgias are a group of diseases that appear similar to each other and other headache disorders but have important differences. Proper diagnosis is crucial for proper treatment.

Impaired Glymphatic and Meningeal Lymphatic Functions in Patients with Chronic Migraine

OBJECTIVE

This study was undertaken to investigate migraine glymphatic and meningeal lymphatic vessel (mLV) functions.

METHODS

Migraine patients and healthy controls (HCs) were prospectively recruited between 2020 and 2023. Diffusion tensor image analysis along the perivascular space (DTI-ALPS) index for glymphatics and dynamic contrast-enhanced magnetic resonance imaging parameters (time to peak [TTP]/enhancement integral [EI]/mean time to enhance [MTE]) for para-superior sagittal (paraSSS)-mLV or paratransverse sinus (paraTS)-mLV in episodic migraine (EM), chronic migraine (CM), and CM with and without medication-overuse headache (MOH) were analyzed. DTI-ALPS correlations with clinical parameters (migraine severity [numeric rating scale]/disability [Migraine Disability Assessment (MIDAS)]/bodily pain [Widespread Pain Index]/sleep quality [Pittsburgh Sleep Quality Index (PSQI)]) were examined.

RESULTS

In total, 175 subjects (112 migraine + 63 HCs) were investigated. DTI-ALPS values were lower in CM (median [interquartile range] = 0.64 [0.12]) than in EM (0.71 [0.13], p = 0.005) and HCs (0.71 [0.09], p = 0.004). CM with MOH (0.63 [0.07]) had lower DTI-ALPS values than CM without MOH (0.73 [0.12], p < 0.001). Furthermore, CM had longer TTP (paraSSS-mLV: 55.8 [12.9] vs 40.0 [7.6], p < 0.001; paraTS-mLV: 51.2 [8.1] vs 44.0 [3.3], p = 0.002), EI (paraSSS-mLV: 45.5 [42.0] vs 16.1 [9.2], p < 0.001), and MTE (paraSSS-mLV: 253.7 [6.7] vs 248.4 [13.8], p < 0.001; paraTS-mLV: 252.0 [6.2] vs 249.7 [1.2], p < 0.001) than EM patients. The MIDAS (p = 0.002) and PSQI (p = 0.002) were negatively correlated with DTI-ALPS index after Bonferroni corrections (p < q = 0.01).

INTERPRETATION

CM patients, particularly those with MOH, have glymphatic and meningeal lymphatic dysfunctions, which are highly clinically relevant and may implicate pathogenesis for migraine chronification. ANN NEUROL 2024;95:583-595.

Profile of Chinese Cluster Headache Register Individual Study (CHRIS): Clinical characteristics, diagnosis and treatment status data of 816 patients in China

BACKGROUND

The clinical profile of cluster headache may differ among different regions of the world, warranting interest in the data obtained from the initial Chinese Cluster Headache Register Individual Study (CHRIS) for better understanding.

METHODS

We conducted a multicenter, prospective, longitudinal cohort study on cluster headache across all 31 provinces of China, aiming to gather clinical characteristics, treatment approaches, imaging, electrophysiological and biological samples.

RESULTS

In total 816 patients were enrolled with a male-to-female ratio of 4.33:1. The mean age at consultation was 34.98 ± 9.91 years, and 24.89 ± 9.77 years at onset. Only 2.33% were diagnosed with chronic cluster headache, and 6.99% had a family history of the condition. The most common bout was one to two times per year (45.96%), lasting two weeks to one month (44.00%), and occurring frequently in spring (76.23%) and winter (73.04%). Of these, 68.50% experienced one to two attacks per day, with the majority lasting one to two hours (45.59%). The most common time for attacks was between 9 am and 12 pm (75.86%), followed by 1 am and 3 am (43.48%). Lacrimation (78.80%) was the most predominant autonomic symptom reported. Furthermore, 39.22% of patients experienced a delay of 10 years or more in receiving a correct diagnosis. Only 35.67% and 24.26% of patients received common acute and preventive treatments, respectively.

CONCLUSION

Due to differences in ethnicity, genetics and lifestyle conditions, CHRIS has provided valuable baseline data from China. By establishing a dynamic cohort with comprehensive multidimensional data, it aims to advance the management system for cluster headache in China.

Regulation of headache response and transcriptomic network by the trigeminal ganglion clock

OBJECTIVE

To characterize the circadian features of the trigeminal ganglion in a mouse model of headache.

BACKGROUND

Several headache disorders, such as migraine and cluster headache, are known to exhibit distinct circadian rhythms of attacks. The circadian basis for these rhythmic pain responses, however, remains poorly understood.

METHODS

We examined trigeminal ganglion ex vivo and single-cell cultures from Per2::LucSV reporter mice and performed immunohistochemistry. Circadian behavior and transcriptomics were investigated using a novel combination of trigeminovascular and circadian models: a nitroglycerin mouse headache model with mechanical thresholds measured every 6 h, and trigeminal ganglion RNA sequencing measured every 4 h for 24 h. Finally, we performed pharmacogenomic analysis of gene targets for migraine, cluster headache, and trigeminal neuralgia treatments as well as trigeminal ganglion neuropeptides; this information was cross-referenced with our cycling genes from RNA sequencing data to identify potential targets for chronotherapy.

RESULTS

The trigeminal ganglion demonstrates strong circadian rhythms in both ex vivo and single-cell cultures, with core circadian proteins found in both neuronal and non-neuronal cells. Using our novel behavioral model, we showed that nitroglycerin-treated mice display circadian rhythms of pain sensitivity which were abolished in arrhythmic Per1/2 double knockout mice. Furthermore, RNA-sequencing analysis of the trigeminal ganglion revealed 466 genes that displayed circadian oscillations in the control group, including core clock genes and clock-regulated pain neurotransmitters. In the nitroglycerin group, we observed a profound circadian reprogramming of gene expression, as 331 of circadian genes in the control group lost rhythm and another 584 genes gained rhythm. Finally, pharmacogenetics analysis identified 10 genes in our trigeminal ganglion circadian transcriptome that encode target proteins of current medications used to treat migraine, cluster headache, or trigeminal neuralgia.

CONCLUSION

Our study unveiled robust circadian rhythms in the trigeminal ganglion at the behavioral, transcriptomic, and pharmacogenetic levels. These results support a fundamental role of the clock in pain pathophysiology.

PLAIN LANGUAGE SUMMARY

Several headache diseases, such as migraine and cluster headache, have headaches that occur at the same time each day. We learned that the trigeminal ganglion, an important pain structure in several headache diseases, has a 24-hour cycle that might be related to this daily cycle of headaches. Our genetic analysis suggests that some medications may be more effective in treating migraine and cluster headache when taken at specific times of the day.

Pediatric Cluster Headache Case Series: Symptomatic Cases and the Migraine Relationship

BACKGROUND

Current criteria help differentiate cluster headache from migraine. However, children may have overlapping features making it difficult to distinguish the 2 conditions, which may delay diagnosis. Differentiating cluster headache from migraine is important regarding treatment as well as diagnostic workup of secondary headache etiologies.

METHODS

Cases at a single pediatric children's hospital from 2015 to 2023 diagnosed with cluster headache before the age of 18 years were reviewed.

RESULTS

Twenty-five cases were identified of which 22 cases met criteria for either chronic, episodic, or probable cluster headache. Three cases were diagnosed with cluster headache by their provider, but documentation was insufficient to meet criteria for cluster headache. There were 16 females and 9 males between ages 6 and 17 years. Five cases were identified as symptomatic, 2 cases as chronic, 7 cases as episodic, and 13 cases as probable cluster headache. Symptomatic etiologies include Graves disease, optic neuritis, prolactinoma, hypothalamic pilocytic astrocytoma with carotid stenosis, and congenital right eye blindness. Migrainous features were common, including 76% with nausea, 36% with vomiting, 68% with photophobia, and 56% with phonophobia. Patients with cluster headache also had an independent diagnosis of migraine in 64%.

CONCLUSION

Children with cluster headache have a high frequency of migrainous symptoms and co-occurrent diagnosis of migraine. A careful history may differentiate cluster headache from migraine and treated accordingly. Children with cluster headache features should undergo screening for secondary causes with appropriate imaging and other studies. Except for prolactinoma, the symptomatic associations noted in this case series have not been reported before.

The genetics and chronobiology of cluster headache

BACKGROUND/HYPOTHESIS

Cluster headache displays uniquely rhythmic patterns in its attack manifestation. This strong chronobiological influence suggests that part of the pathophysiology of cluster headache is distinctly different from migraine and has prompted genetic investigations probing these systems.

METHODS

This is a narrative overview of the cluster headache chronobiological phenotype from the point of view of genetics covering existing knowledge, highlighting the specific challenges in cluster headache and suggesting novel research approaches to overcome these.

RESULTS

The chronobiological features of cluster headache are a hallmark of the disorder and while discrepancies between study results do exist, the main findings are highly reproducible across populations and time. Particular findings in subgroups indicate that the heritability of the disorder is linked to chronobiological systems. Meanwhile, genetic markers of circadian rhythm genes have been implicated in cluster headache, but with conflicting results. However, in two recently published genome wide association studies two of the identified four loci include genes with an involvement in circadian rhythm, MER proto-oncogene, tyrosine kinase and four and a half LIM domains 5. These findings strengthen the involvement of circadian rhythm in cluster headache pathophysiology.

CONCLUSION/INTERPRETATION

Studying chronobiology and genetics in cluster headache presents challenges unique to the disorder. Researchers are overcoming these challenges by pooling various data from different cohorts and performing meta-analyses providing novel insights into a classically enigmatic disorder. Further progress can likely be made by combining deep pheno- and genotyping.

Effects of Non-Invasive Neuromodulation of the Vagus Nerve for the Management of Cluster Headache: A Systematic Review

BACKGROUND

Cluster headache (CH) is a type of headache that has a global prevalence of 0.5-3/1000 people, provokes severe, strictly unilateral pain through the first branch of the trigeminal nerve, and is associated with observable autonomous responses. CH provokes intense pain and decreases quality of life.

OBJECTIVE

In this study, we aimed to carry out a systematic review of the effectiveness of non-invasive neuromodulation of the vagus nerve in patients with cluster headaches, which was registered on PROSPERO No. CRD42021265126.

METHODS

Six databases were used from their date of inception to February 2023 to obtain studies with the group intervention of non-invasive neuromodulation of the vagus nerve for cluster headache, with outcomes based on pain attacks, duration, and disabilities. Data on the subjects, group intervention, main outcomes, and results were collected by two authors.

RESULTS

The search provided 1003 articles, with three clinical trials being eligible for inclusion in the review. The methodological quality scores ranged from 6 to 8 points (mean: 7.3, SD: 0.8) out of a maximum of 10 points. The post-treatment results showed some positive effects using n-VNS as a treatment for cluster headache, more specifically regarding cervical neuromodulation of the vagus nerve.

CONCLUSIONS

The systematic review found moderate-to-high-quality evidence supporting that n-VNS and cervical n-VNS may have some positive effects at the end of the treatment being effective to relieve the frequency and intensity of cluster headaches. The poor quantity of studies available and the lack of homogeneity in the study protocols did not allow the pooling of data for a meta-analysis.

Patients with cluster headache show signs of insomnia and sleep related stress: results from an actigraphy and self-assessed sleep study

BACKGROUND

Cluster headache (CH) is a primary headache disorder which is characterized by circadian timing of headache attacks, usually at nighttime, in around two thirds of patients. Patients with CH often report sleep difficulties, though it is unknown whether this is a cause or a consequence of nightly headache attacks.

OBJECTIVE

In this case-control study we have assessed sleep quality in study participants with CH in cluster bout respectively in remission, compared to a control group of neurologically healthy individuals to investigate the potential connection between sleep and CH.

METHODS

Fifty study participants with CH and 42 controls were recruited for sleep assessment. Sleep was recorded using MotionWatch 8 actigraphs (CamNTech) for a period of two weeks. Study participants were instructed to wear the unit during rest and sleep and to fill out a sleep diary daily through the two-weeks period.

RESULTS

Results from actigraphy recordings and sleep diaries suggested that patients with CH spend longer time in bed than controls (CH 8.1 hours vs. Controls 7.7 hours, p=0.03), but do not sleep more than controls (CH 6.7 hours vs. controls 6.5 hours, p=0.3). In addition, CH patients reported increased sleep latency (p=0.003), particularly during, but not restricted to, cluster bouts. Study participants with CH further reported higher levels of stress at bedtime (p=0.01), and they felt less well rested than controls (p=0.001).

CONCLUSION

Our analysis suggests that sleep is negatively affected in CH both in cluster bout and in remission, manifesting in symptoms consistent with insomnia such as prolonged sleep latency and increased time in bed.

Management of cluster headache: Treatments and their mechanisms

BACKGROUND

The management of cluster headache is similar to that of other primary headache disorders and can be broadly divided into acute and preventive treatments. Acute treatments for cluster headache are primarily delivered via rapid, non-oral routes (such as inhalation, nasal, or subcutaneous) while preventives include a variety of unrelated treatments such as corticosteroids, verapamil, and galcanezumab. Neuromodulation is becoming an increasingly popular option, both non-invasively such as vagus nerve stimulation when medical treatment is contraindicated or side effects are intolerable, and invasively such as occipital nerve stimulation when medical treatment is ineffective. Clinically, this collection of treatment types provides a range of options for the informed clinician. Scientifically, this collection provides important insights into disease mechanisms.

METHODS

Two authors performed independent narrative reviews of the literature on guideline recommendations, clinical trials, real-world data, and mechanistic studies.

RESULTS

Cluster headache is treated with acute treatments, bridge treatments, and preventive treatments. Common first-line treatments include subcutaneous sumatriptan and high-flow oxygen as acute treatments, corticosteroids (oral or suboccipital injections) as bridge treatments, and verapamil as a preventive treatment. Some newer acute (non-invasive vagus nerve stimulation) and preventive (galcanezumab) treatments have excellent clinical trial data for episodic cluster headache, while other newer treatments (occipital nerve stimulation) have been specifically tested in treatment-refractory chronic cluster headache. Most treatments are suspected to act on the trigeminovascular system, the autonomic system, or the hypothalamus.

CONCLUSIONS

The first-line treatments have not changed in recent years, but new treatments have provided additional options for patients.