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.

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.

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

BACKGROUND AND OBJECTIVES

Cluster headache and migraine have circadian features at multiple levels (cellular, systems, and behavioral). A thorough understanding of their circadian features informs their pathophysiologies.

METHODS

A librarian created search criteria in MEDLINE Ovid, Embase, PsycINFO, Web of Science, and Cochrane Library. Two physicians independently performed the remainder of the systematic review/meta-analysis using Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Separate from the systematic review/meta-analysis, we performed a genetic analysis for genes with a circadian pattern of expression (clock-controlled genes or CCGs) by cross-referencing genome-wide association studies (GWASs) of headache, a nonhuman primate study of CCGs in a variety of tissues, and recent reviews of brain areas relevant in headache disorders. Altogether, this allowed us to catalog circadian features at the behavioral level (circadian timing, time of day, time of year, and chronotype), systems level (relevant brain areas where CCGs are active, melatonin and corticosteroid levels), and cellular level (core circadian genes and CCGs).

RESULTS

For the systematic review and meta-analysis, 1,513 studies were found, and 72 met the inclusion criteria; for the genetic analysis, we found 16 GWASs, 1 nonhuman primate study, and 16 imaging reviews. For cluster headache behavior, meta-analyses showed a circadian pattern of attacks in 70.5% (3,490/4,953) of participants across 16 studies, with a clear circadian peak between 21:00 and 03:00 and circannual peaks in spring and autumn. Chronotype was highly variable across studies. At the systems level, lower melatonin and higher cortisol levels were reported in cluster headache participants. At the cellular level, cluster headache was associated with core circadian genes CLOCK and REV-ERBα, and 5 of the 9 cluster headache susceptibility genes were CCGs. For migraine behavior, meta-analyses showed a circadian pattern of attacks in 50.1% (2,698/5,385) of participants across 8 studies, with a clear circadian trough between 23:00 and 07:00 and a broad circannual peak between April and October. Chronotype was highly variable across studies. At the systems level, urinary melatonin levels were lower in participants with migraine and even lower during an attack. At the cellular level, migraine was associated with core circadian genes CK1δ and RORα, and 110 of the 168 migraine susceptibility genes were CCGs.

DISCUSSION

Cluster headache and migraine are highly circadian at multiple levels, reinforcing the importance of the hypothalamus. This review provides a pathophysiologic foundation for circadian-targeted research into these disorders.

TRIAL REGISTRATION INFORMATION

The study was registered with PROSPERO (registration number CRD42021234238).

Primary headache disorders: From pathophysiology to neurostimulation therapies

Primary headache disorders including migraine, cluster headache, and tension-type headache are among the most common disabling diseases worldwide. The unclear pathogenesis of primary headache disorders has led to high rates of misdiagnosis and limited available treatment options. In this review, we have summarized the pathophysiological factors for a better understanding of primary headache disorders. Advances in functional neuroimaging, genetics, neurophysiology have indicated that cortical hyperexcitability, regional brain dysfunction, central sensitization and neuroplasticity changes play vital roles in the development of primary headache disorders. Moreover, we have also discussed a series of neurostimulation approaches with their stimulation mechanism, safety and efficacy for prevention and treatment of primary headache disorders. Noninvasive or implantable neurostimulation techniques show great promise for treating refractory primary headache disorders.

Sleep and Chronobiology as a Key to Understand Cluster Headache

The cluster headache is a primary headache characterized by attacks of unilateral pain associated with ipsilateral cranial autonomic features. These attacks recur in clusters during the years alternating with periods of complete remission, and their onset is often during the night. This annual and nocturnal periodicity hides a strong and mysterious link among CH, sleep, chronobiology and circadian rhythm. Behind this relationship, there may be the influence of genetic components or of anatomical structures such as the hypothalamus, which are both involved in regulating the biological clock and contributing even to the periodicity of cluster headaches. The bidirectional relationship manifests itself also with the presence of sleep disturbances in patients affected by cluster headaches. What if the key to studying the physiopathology of such disease could rely on the mechanisms of chronobiology? The purpose of this review is to analyze this link in order to interpret the pathophysiology of cluster headaches and the possible therapeutic implications.

Cranial Autonomic Symptoms and Neck Pain in Differential Diagnosis of Migraine

Cranial autonomic symptoms and neck pain have been reported to be highly prevalent in migraine, although they are rarely considered in clinical evaluation. The aim of this review is to focus on the prevalence, pathophysiology, and clinical characteristics of these two symptoms, and their importance in the differential diagnosis between migraines and other headaches. The most common cranial autonomic symptoms are aural fullness, lacrimation, facial/forehead sweating, and conjunctival injection. Migraineurs experiencing cranial autonomic symptoms are more likely to have more severe, frequent, and longer attacks, as well as higher rates of photophobia, phonophobia, osmophobia, and allodynia. Cranial autonomic symptoms occur due to the activation of the trigeminal autonomic reflex, and the differential diagnosis with cluster headaches can be challenging. Neck pain can be part of the migraine prodromal symptoms or act as a trigger for a migraine attack. The prevalence of neck pain correlates with headache frequency and is associated with treatment resistance and greater disability. The convergence between upper cervical and trigeminal nociception via the trigeminal nucleus caudalis is the likely mechanism for neck pain in migraine. The recognition of cranial autonomic symptoms and neck pain as potential migraine features is important because they often contribute to the misdiagnosis of cervicogenic problems, tension-type headache, cluster headache, and rhinosinusitis in migraine patients, delaying appropriate attack and disease management.

Debate: Are cluster headache and migraine distinct headache disorders?

Cluster headache and migraine are regarded as distinct primary headaches. While cluster headache and migraine differ in multiple aspects such as gender-related and headache specific features (e.g., attack duration and frequency), both show clinical similarities in trigger factors (e.g., alcohol) and treatment response (e.g., triptans). Here, we review the similarities and differences in anatomy and pathophysiology that underlie cluster headache and migraine, discuss whether cluster headache and migraine should indeed be considered as two distinct primary headaches, and propose recommendations for future studies. Video recording of the debate held at the 1st International Conference on Advances in Migraine Sciences (ICAMS 2022, Copenhagen, Denmark) is available at https://www.youtube.com/watch?v=uUimmnDVTTE .

Feasibility, Utility, and Interrater Reliability of the Cluster Headache Severity Scale, Cluster Headache Quality of Life, Cluster Headache Index, and 6-Item Headache Impact Test in Pediatric Cluster Headache

Introduction: Cluster headache is rare in children and only a few clinical studies have systematically evaluated cluster headache in children. Methods: This study was conducted between August 2019 and December 2021 with the primary aim to evaluate the feasibility and utility of the Cluster Headache Severity Scale in determining the severity of cluster headache in patients aged less than 18 years and monitoring response to prescribed treatment. Secondary objectives were to evaluate the feasibility and utility of Cluster Headache Quality of Life, Cluster Headache Index, and 6-item Headache Impact Test in pediatric cluster headache patients to assess the quality of life, severity, and impact of cluster headache. Results: A total of 32 children (age of onset 11.9 ± 2.3 years, age of diagnosis 13.7 ± 2.4 years, 68% boys) were enrolled. Although 30 cases had their headache episodes occurring during nighttime, only 16 children had a Children's Sleep Habits Questionnaire (CSHQ) score >41 at baseline. All children responded to prednisolone as bridging therapy and 23 of 32 showed adequate pain relief after sumatriptan nasal spray for an acute attack. The average time taken for completion of Cluster Headache Index, Cluster Headache Severity Scale, Cluster Headache Quality of Life, and Headache Impact Test-6 scores were 5.2 ± 0.7, 5.1 ± 0.8, 27.4 ± 3.5, and 6.2 ± 0.8 minutes, respectively. The interrater reliability was good for Cluster Headache Severity Scale, Cluster Headache Quality of Life, and Headache Impact Test-6 (Cronbach α 0.93, 0.81, and 0.89, respectively). There was a strong positive correlation between the Cluster Headache Severity Scale score with Headache Impact Test-6 score and Cluster Headache Quality of Life score (correlation coefficient r = 0.90 and 0.98). Conclusion: Majority of pediatric cluster headache patients are likely to respond to prednisolone and sumatriptan. Cluster Headache Severity Scale, Cluster Headache Quality of Life, and Headache Impact Test-6 can be used for pediatric cluster headache patients for treatment monitoring.

CGRP-Targeted Therapy for Episodic and Chronic Cluster Headache

PURPOSE OF REVIEW

Chronic cluster headache (CH) substantially affects patients' quality of life, and treatment remains challenging. The current article reviewed controlled studies for new treatment options targeting calcitonin gene-related peptide (CGRP) or its receptors in CH and discussed the current gaps and future directions for the treatment of chronic CH.

RECENT FINDINGS

Two anti-CGRP monoclonal antibodies (i.e., galcanezumab and fremanezumab) completed randomized-control trials for efficacy for the preventive treatment of episodic and chronic CH. Galcanezumab was effective for preventing episodic CH but not chronic CH. Fremanezumab was ineffective in preventing episodic and chronic CH. Studies for other anti-CGRP monoclonal antibodies and CGRP antagonists are still pending for results. There are no randomized controlled trials for CGRP-targeted therapies that showed efficacy for chronic CH prevention. The different responses to galcanezumab between episodic and chronic CH may be due to the study design, i.e., the allowance of concomitant preventive therapies in the chronic CH study but not in the episodic CH study. Another reason for the discrepancies is the different roles and sensitivity of CGRP in chronic CH.

The economic and personal burden of cluster headache: a controlled cross-sectional study

Background

Cluster headache is a less-prevalent primary headache disorder but is overrepresented with regards to use of health care and social services. More insight into the socioeconomic impact is required.

Methods

We investigated both the personal and societal disease burden and cost in 400 patients with well-classified cluster headache according to the ICHD-criteria and 200 sex- and age matched controls. All participants completed a cross sectional questionnaire and semi-structured interview.

Results

Patients with chronic cluster headache constituted 146 out of 400 (37%). Overall, restriction in personal and/or professional life was reported by 94% of patients during attack periods. Even in remission, nine times as many episodic patients rated their health as poor/very poor compared to controls (9% vs 1%, p = 0.002). For chronic patients, the odds of rating health as good/very good were ten times lower compared to controls (OR:10.10, 95%CI:5.29–18.79. p < 0.001) and three times lower compared to episodic patients in remission (OR:3.22, 95%CI:1.90–5.47, p < 0.001). Additionally, chronic cluster headache patients were 5 times more likely to receive disability pension compared to episodic (OR:5.0, 95%CI:2.3–10.9, p < 0.001). The mean direct annual costs amounted to 9,158€ and 2,763€ for chronic and episodic patients, respectively (p < 0.001). We identified a substantial loss of productivity due to absence from work resulting in a higher indirect cost of 11,809 €/year/patient in the chronic population and 3,558 €/year/patient in the episodic population. Presenteeism could not be quantified but productivity was reduced in patients by 65% in periods with attacks compared to controls.

Conclusion

Cluster headache has a major negative impact on personal life, self-perceived health, and societal cost. Patients with the chronic variant are vastly more burdened. Patients with the episodic form were still markedly affected during the remission period. This study highlights the need for more effective therapy to lighten the burden on patients and society.

Cluster headache epidemiology including pediatric onset, sex, and ICHD criteria: Results from the International Cluster Headache Questionnaire

OBJECTIVE

To validate the diagnoses and to investigate epidemiological data from an international, non-clinic-based, and large (n = 1604) survey of participants with cluster headache.

BACKGROUND

There are several limitations in current epidemiological data in cluster headache including a lack of large non-clinic-based studies. There is also limited information on several aspects of cluster headache, such as pediatric incidence.

METHODS

The International Cluster Headache Questionnaire was an internet-based survey that included questions on cluster headache demographics, criteria from the International Classification of Headache Disorders (ICHD), and medications.

RESULTS

A total of 3251 subjects participated in the survey, and 1604 respondents met ICHD criteria for cluster headache. For validation, we interviewed a random sample of 5% (81/1604) of participants and confirmed the diagnosis of cluster headache in 97.5% (79/81). Pediatric onset was found in 27.5% (341/1583) of participants, and only 15.2% (52/341) of participants with pediatric onset were diagnosed before the age of 18. Men were more likely to have episodic cluster headache between ages 10 and 50, but the sex ratio was approximately equal for other ages. An overwhelming majority of respondents had at least one autonomic feature (99.0%, 1588/1604) and had restlessness (96.6%, 1550/1604), but many also had prototypical migrainous features including photophobia or phonophobia (50.1%, 804/1604), pain aggravated by physical activity (31.4%, 503/1604), or nausea and vomiting (27.5%, 441/1604). Interestingly, the first-line medications for acute treatment (oxygen) and preventive treatment (calcium channel blockers) were perceived as significantly less effective in chronic cluster headache (3.2 ± 1.1 and 2.1 ± 1.0 respectively on a 5-point ordinal scale) compared with episodic cluster headache (3.5 ± 1.0 and 2.4 ± 1.1, respectively, p < 0.001 for both comparisons).

CONCLUSIONS

Cluster headache often occurs in the pediatric population, although they are typically not diagnosed until adulthood. The onset of cluster headache is the inverse of that in migraine; in migraine women are more likely to have migraine between ages 10 and 50 but the sex ratio is approximately equal otherwise. Prototypical migrainous features are not useful in differentiating cluster headache from migraine. Participant data from a large international study also suggest that chronic cluster headache is not only less responsive to newer treatments (like noninvasive vagus nerve stimulation and galcanezumab), but to traditional first-line treatments as well.

Reference programme: diagnosis and treatment of headache disorders and facial pain. Danish Headache Society, 3rd edition, 2020

Headache and facial pain are among the most common, disabling and costly diseases in Europe, which demands for high quality health care on all levels within the health system. The role of the Danish Headache Society is to educate and advocate for the needs of patients with headache and facial pain. Therefore, the Danish Headache Society has launched a third version of the guideline for the diagnosis, organization and treatment of the most common types of headaches and facial pain in Denmark. The second edition was published in Danish in 2010 and has been a great success, but as new knowledge and treatments have emerged it was timely to revise the guideline. The recommendations for the primary headaches and facial pain are largely in accordance with the European guidelines produced by the European Academy of Neurology. The guideline should be used a practical tool for use in daily clinical practice for primary care physicians, neurologists with a common interest in headache, as well as other health-care professionals treating headache patients. The guideline first describes how to examine and diagnose the headache patient and how headache treatment is organized in Denmark. This description is followed by sections on the characteristics, diagnosis and treatment of each of the most common primary and secondary headache disorders and trigeminal neuralgia. The guideline includes many tables to facilitate a quick overview. Finally, the particular challenges regarding migraine and female hormones as well as headache in children are addressed.

The first-line cluster headache medication verapamil alters the circadian period and elicits sex-specific sleep changes in mice

Verapamil is the first-line preventive medication for cluster headache, an excruciating disorder with strong circadian features. Whereas second- and third-line preventives include known circadian modulators, such as melatonin, corticosteroids, and lithium, the circadian effects of verapamil are poorly understood. Here, we characterize the circadian features of verapamil using both in vitro and in vivo models. In Per2::LucSV reporter fibroblasts, treatment with verapamil (0.03-10 µM) showed a dose-dependent period shortening of the reporter rhythm which reached a nadir at 1 µM, and altered core clock gene expression at 10 µM. Mouse wheel-running activity with verapamil (1 mg/mL added to the drinking water) also resulted in significant period shortening and activity reduction in both male and female free-running wild-type C57BL6/J mice. The temporal patterns of activity reduction, however, differ between the two sexes. Importantly, piezo sleep recording revealed sexual dimorphism in the effects of verapamil on sleep timing and bout duration, with more pronounced adverse effects in female mice. We also found altered circadian clock gene expression in the cerebellum, hypothalamus, and trigeminal ganglion of verapamil-treated mice. Verapamil did not affect reporter rhythms in ex vivo suprachiasmatic nucleus (SCN) slices from Per2:Luc reporter mice, perhaps due to the exceptionally tight coupling in the SCN. Thus, verapamil affects both peripheral (trigeminal ganglion) and central (hypothalamus and cerebellum) nervous system structures involved in cluster headache pathophysiology, possibly with network effects instead of isolated SCN effects. These studies suggest that verapamil is a circadian modulator in laboratory models at both molecular and behavioral levels, and sex is an important biological variable for cluster headache medications. These observations highlight the circadian system as a potential convergent target for cluster headache medications with different primary mechanisms of action.

Temporal distribution of emergency room visits in patients with migraine and other headaches

Background: Headache is a leading reason for presentation to the emergency department (ED) with migraine being the most frequently headache. To ensure the adequate staffing of healthcare providers during peak times of headache visits, we analyzed the temporal distribution of emergency department visits in patients presenting with headache and/or migraine.Research design and methods: The authors conducted an ecological study, including all consecutive visits to the ED for headache. Patients were classified according to the IHS Classification. We analyzed circadian, circaseptan and circannual patterns for number of visits, comparing migraine patients with other headache patients.Results: There were 2132 ED visits for headache, including primary headache in 1367 (64.1%) cases; migraine in 963 (45.2%); secondary headache in 404 (18.9%); and unspecified headache in 366 (17.1%). The circadian pattern showed peaks around 11:00-13:00 and 17:00-19:00, with visits during the night shift 45% less frequent (p < 0.001). The circaseptan pattern showed a peak on Monday-Tuesday and a low point on Sunday (p < 0.007). The circannual pattern peaked in March and decreased in June.Conclusions: ED visits for headache showed specific circadian, circaseptan and circannual variations. No differences were found in these patterns when comparing migraine patients to other headache patients.

Current Understanding of the Chronobiology of Cluster Headache and the Role of Sleep in Its Management

Cluster headache is uniquely rhythmic in its occurrence both diurnally and annually. This has implications for the clinical approach to the patient but also for our understanding of the role of central structures in its pathological basis. Many intrinsic and extrinsic factors seem to influence CH rhythmicity, including genetics. The proclivity for attacks to occur at night and the possible association with particular sleep phenomena, including sleep apnea, have motivated a number of studies which has improved our understanding but many questions remain unanswered. The sleep-headache interaction seems to be bidirectional and possibly both direct and indirect. The latter could involve more disperse networks of homeostatic regulation, which may better encompass recent observations. Treatment of the headache patient with concurrent sleep problems can be particularly challenging, especially considering side-effects and interactions of commonly used medications. While current treatment guidelines do not incorporate chronotherapeutic thinking, some evidence may suggest that application of such principles on an individual level may be beneficial.

Real-life treatment of cluster headache in a tertiary headache center - results from the Danish Cluster Headache Survey

BACKGROUND

Pharmacological treatment of cluster headache constitutes the core of clinical management, but evidence is sparse. We aimed to generate insight in the existing treatment and identify associations between clinical features and treatment response.

METHODS

Patients aged 18-65 diagnosed with cluster headache according to the ICHD-2 completed a questionnaire followed by a structured interview. Multiple logistic regression was used to identify associations.

RESULTS

The population consisted of 400 patients with an episodic: chronic ratio of 1.7:1. Episodic patients were more likely to respond to triptans (odds ratio = 1.77, confidence interval: 1.08-2.91, p = 0.023) and oxygen (odds ratio = 1.64, confidence interval: 1.05-2.57, p = 0.031) than chronic. Oxygen response was less likely if pain intensity was very severe (odds ratio = 0.53, confidence interval: 0.33-2.57, p = 0.006) and the risk of a poor response increased with disease duration (odds ratio = 0.79, confidence interval: 0.65-0.96, p = 0.016). Among current users of sumatriptan injection and oxygen, the proportion achieving 100% relief was higher with sumatriptan injection (p > 0.001) than with oxygen. No associations were identified regarding verapamil. Only 57% of current users of preventive medication responded at a 50% level.

CONCLUSION

Episodic cluster headache is more responsive to acute therapy than chronic. Further, sumatriptan injection was more effective than oxygen and the responder-rate was limited with verapamil. More effective acute and preventive therapies are needed for cluster headache patients.

Cluster headache in Asian populations: Similarities, disparities, and a narrative review of the mechanisms of the chronic subtype

OBJECTIVE

Headache disorders like migraine show geographic and ethnic differences between Asian and European/North American countries. In cluster headache, these differences are rarely mentioned and discussed. This article aimed to review the characteristics of cluster headache in Asian countries and compare the clinical features to those in European and North American populations.

METHODS

We conducted a narrative literature review on the demographics, clinical presentations, and treatments of cluster headache in Asian countries.

RESULTS

Patients with cluster headache in Asian populations showed a stronger male predominance compared to European and North American populations. Chronic cluster headache was rare in Asian countries. The clinical presentation of restlessness was not as common in Asian as it was in European and North American countries, and Asian patients with aura were extremely rare. Patients in Asian countries may have a lower circadian rhythmicity of cluster headache and a lower headache load, as demonstrated by lower attack frequencies per day, bout frequencies, and bout durations.

CONCLUSIONS

Regional differences in the presentation of cluster headache exist. Greater awareness for cluster headache should be raised in Asian regions, and further studies are warranted to elucidate the mechanisms behind observed differences.

Phase 3 randomized, placebo-controlled study of galcanezumab in patients with chronic cluster headache: Results from 3-month double-blind treatment

Objective

To report efficacy and safety of galcanezumab in adults with chronic cluster headache.

Background

Galcanezumab is a humanized monoclonal antibody that binds to calcitonin gene-related peptide and inhibits its biological activity.

Methods

This study comprised a prospective baseline period, a 12-week double-blind, placebo-controlled treatment period, and a 52-week open-label period. Up to six protocol-specified concomitant preventive medications were allowed if patients were on a stable dose for 2 months prior to the prospective baseline period. Patients were randomized 1:1 to monthly subcutaneous galcanezumab (300 mg) or placebo. The primary endpoint was overall mean change from baseline in weekly attack frequency with galcanezumab compared to placebo. Key secondary endpoints were ≥50% response rate and percentage of patients meeting sustained response. Results from the double-blind treatment period are reported.

Results

A total of 237 patients were randomized and treated (120 placebo; 117 galcanezumab). At baseline, the mean age was 45 years and 63% were using ≥1 preventive drug. The primary endpoint was not met; mean change in weekly attack frequency was −4.6 placebo versus −5.4 galcanezumab (p = 0.334). Key secondary endpoints also were not met. Injection site-related treatment-emergent adverse events were more common in the galcanezumab than the placebo group, with significantly more injection site erythema.

Conclusion

Treatment with galcanezumab 300 mg did not achieve its primary and key secondary endpoints. This study underscores the potential distinct biology of cCH as well as the significant unmet need for safe, effective, and well-tolerated preventive treatment. The safety profile of galcanezumab in cCH is consistent with that observed in trials of episodic CH and migraine.

Trial registration

NCT02438826; https://www.clinicaltrials.gov/ct2/show/NCT02438826.

Clinical features of chronic cluster headache based on the third edition of the International Classification of Headache Disorders: A prospective multicentre study

The criterion for the remission period of chronic cluster headache (CCH) was recently revised from < 1 month to < 3 months in the third edition of the International Classification of Headache Disorders (ICHD-3). However, information on the clinical features of CCH based on the ICHD-3 criteria is currently limited. The present study aimed to investigate the clinical features of CCH based on ICHD-3 using data from the Korean Cluster Headache Registry (KCHR). The KCHR is a multicentre prospective registry of patients with cluster headache (CH) from 15 hospitals. Among the 250 participants with CH, 12 and 176 participants were classified as having CCH and episodic cluster headache (ECH), respectively. Among 12 participants with CCH, 6 (50%) had remission periods of < 1 month, and the remaining 6 (50%) had a remission period of 1–3 months. Six participants had CCH from the time of onset of CH, and in the other 6 participants, CCH evolved from ECH. CCH subjects had later age of onset of CH, developed the condition after a longer interval after CH onset, and had more migraine and less nasal congestion and/or rhinorrhoea than ECH subjects. Clinical features of CCH with remission periods < 1 month were not significantly different from those of CCH with remission periods of 1–3 months, except for the total number of bouts. More current smoking and less diurnal rhythmicity were observed in participants with CCH evolved from ECH compared to those with ECH. In conclusion, the number of subjects with CCH doubled when the revised ICHD-3 criteria were used. Most of clinical characteristics of CCH did not differ when the previous and current version of ICHD was applied and compared. Some clinical features of CCH were different from those of ECH, and smoking may have a role in CH chronification.

Chronobiology and Sleep in Cluster Headache

Background

Cluster headache attacks follow a striking circadian rhythm with an intriguing influence of sleep. We aim to investigate differences in sleep quality, chronotype, and the ability to alter individual sleep rhythms in episodic and chronic cluster headache patients vs controls.

Methods

Cluster headache patients and non‐headache controls from the Dutch Leiden University Cluster headache neuro‐Analysis program aged 18 and above completed web‐based questionnaires in a cross‐sectional study.

Results

A total of 478 episodic, 147 chronic cluster headache patients and 367 controls participated. Chronic cluster headache patients had more often early chronotypes than controls, as measured by mid‐sleep phase (P = .021 adjusted B −15.85 minutes CI −29.30; −2.40). Compared to controls, chronic cluster headache participants were less able to alter their sleep rhythms (P < .001 adjusted B −1.65 CI −2.55; 0.74), while episodic cluster headache participants reported more difficulty in coping with reduced sleep (P = .025 adjusted B 0.75 CI 0.09; 1.40). Sleep quality was reduced in both types of cluster headache compared to controls (“poor sleepers”: 71.4% (105/147) in chronic and 48.3% (235/367) in episodic cluster headache vs 25.6% (94/367) in controls; both P < .001; episodic adjusted B −1.71 CI 0.10; 0.32; chronic adjusted B −0.93 CI 0.24; 0.65).

Conclusion

Sleep quality is decreased in both episodic and chronic cluster headache, most likely caused by cluster headache attacks that strike during the night. Episodic cluster headache patients report more difficulty in coping with reduced sleep, while chronic patients are less able to alter their sleep rhythm. Although not directly proven, cluster headache patients will likely benefit from a structured, regular daily schedule.

Genetics of cluster headache

BACKGROUND

Cluster headache is the most severe primary headache disorder. A genetic basis has long been suggested by family and twin studies; however, little is understood about the genetic variants that contribute to cluster headache susceptibility.

METHODS

We conducted a literature search of the MEDLINE database using the PubMed search engine to identify all human genetic studies for cluster headache. In this article we provide a review of those genetic studies, along with an overview of the pathophysiology of cluster headache and a brief review of migraine genetics, which have both been significant drivers of cluster headache candidate gene selection.

RESULTS

The investigation of cluster headache genetic etiology has been dominated by candidate gene studies. Candidate selection has largely been driven by the pathophysiology, such as the striking rhythmic nature of the attacks, which spurred close examination of the circadian rhythm genes CLOCK and HCRTR2. More recently, unbiased genetic approaches such as genome-wide association studies (GWAS) have yielded new genetic avenues of interest including ADCYAP1R1 and MME.

CONCLUSIONS

The majority of candidate genes studied for cluster headache suffer from poor reproducibility. Broader genetic interrogation through larger unbiased GWAS, exome, and whole genome studies may provide more robust candidates, and in turn provide a clearer understanding of the causes of cluster headache.

Sleep in cluster headache revisited: Results from a controlled actigraphic study

Background and aim

Cluster headache attacks exhibit a nocturnal predilection, but little is known of long-term sleep and circadian rhythm. The aim was to compare actigraphy measures, firstly in episodic cluster headache patients in bout and in remission and, secondly, to compare each disease phase with controls.

Methods

Episodic cluster headache patients (ICHD III-beta), from the Danish Headache Center and healthy, age- and sex-matched controls participated. Sleep and activity were measured using actigraphy continuously for 2 weeks, along with sleep diaries and, for patients, also attack registration.

Results

Patients in bout (n = 17, 2.3 attacks/day) spent more time in bed (8.4 vs. 7.7 hours, p = 0.021) and slept more (7.2 vs. 6.6 hours, p = 0.036) than controls (n = 15). In remission (n = 11), there were no differences compared with controls. Neither were there differences between patients in the two disease phases. In five patients, attacks/awakenings occurred at the same hour several nights in a row.

Conclusion

Actigraphy offers the possibility of a continuous and long study period in a natural (non-hospital) environment. The study indicates that sleep does not differ between the bout and remission phase of episodic cluster headache. The repeated attacks/awakenings substantiate that circadian or homeostatic mechanisms are involved in the pathophysiology. The protocol was made available at ClinicalTrials.gov (NCT02853487).