Persistence of attacks of cluster headache after trigeminal nerve root section

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.

Pathophysiology of cluster headache: From the trigeminovascular system to the cerebral networks

BACKGROUND

Despite advances in neuroimaging and electrophysiology, cluster headache's pathogenesis remains unclear. This review will examine clinical neurophysiology studies, including electrophysiological and functional neuroimaging, to determine if they might help us construct a neurophysiological model of cluster headache.

RESULTS

Clinical, biochemical, and electrophysiological research have implicated the trigeminal-parasympathetic system in cluster headache pain generation, although the order in which these two systems are activated, which may be somewhat independent, is unknown. Electrophysiology and neuroimaging have found one or more central factors that may cause seasonal and circadian attacks. The well-known posterior hypothalamus, with its primary circadian pacemaker suprachiasmatic nucleus, the brainstem monoaminergic systems, the midbrain, with an emphasis on the dopaminergic system, especially when cluster headache is chronic, and the descending pain control systems appear to be involved. Functional connection investigations have verified electrophysiological evidence of functional changes in distant brain regions connecting to wide cerebral networks other than pain.

CONCLUSION

We propose that under the impact of external time, an inherited misalignment between the primary circadian pacemaker suprachiasmatic nucleus and other secondary extra- suprachiasmatic nucleus clocks may promote disturbance of the body's internal physiological clock, lowering the threshold for bout recurrence.

Central generators of migraine and autonomic cephalalgias as targets for personalized pain management: Translational links

BACKGROUND AND OBJECTIVE

Migraine oscillates between different states in association with internal homeostatic functions and biological rhythms that become more easily dysregulated in genetically susceptible individuals. Clinical and pre-clinical data on migraine pathophysiology support a primary role of the central nervous system (CNS) through 'dysexcitability' of certain brain networks, and a critical contribution of the peripheral sensory and autonomic signalling from the intracranial meningeal innervation. This review focuses on the most relevant back and forward translational studies devoted to the assessment of CNS dysfunctions involved in primary headaches and discusses the role they play in rendering the brain susceptible to headache states.

METHODS AND RESULTS

We collected a body of scientific literature from human and animal investigations that provide a compelling perspective on the anatomical and functional underpinnings of the CNS in migraine and trigeminal autonomic cephalalgias. We focus on medullary, hypothalamic and corticofugal modulation mechanisms that represent strategic neural substrates for elucidating the links between trigeminovascular maladaptive states, migraine triggering and the temporal phenotype of the disease.

CONCLUSION

It is argued that a better understanding of homeostatic dysfunctional states appears fundamental and may benefit the development of personalized therapeutic approaches for improving clinical outcomes in primary headache disorders.

SIGNIFICANCE

This review focuses on the most relevant back and forward translational studies showing the crucial role of top-down brain modulation in triggering and maintaining primary headache states and how these central dysfunctions may interact with personalized pain management strategies.

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.

[Galcanezumab for episodic and chronic cluster headache]

BACKGROUND

Cluster headache (CH) is a highly debilitating headache disorder characterized by frequent attacks of excruciating unilateral pain accompanied by cranial autonomic symptoms. Calcitonin gene-related peptide (CGRP) is implicated in the pathophysiology of CH.

OBJECTIVES

Preventive efficacy and tolerability of the anti-CGRP antibody galcanezumab in patients with episodic (eCH) and chronic CH (cCH). Review of the study results and the challenges in developing drugs for the preventive treatment of CH.

MATERIALS AND METHODS

In two international multicenter phase III trials galcanezumab 300 mg given subcutaneously every 4 weeks was compared with placebo. The double-blind study period (8 weeks in eCH, 12 weeks in cCK) was preceded by a baseline period in both trials. The primary endpoint was the reduction in weekly attack frequency.

RESULTS

In the eCH trial, 106 patients were randomized to either galcanezumab (n = 49) or placebo (n = 57). The mean weekly attack frequency during the first 3 weeks decreased by 52% in the galcanezumab group compared with 27% in the placebo group (p = 0.036). In the cCH trial, 237 patients were randomized to galcanezumab (n = 117) or placebo (n = 120). The primary endpoint was not met in this study. The reduction in mean weekly attack rate was 5.4 with galcanezumab versus 4.6 with placebo (p = 0.334). Galcanezumab was well tolerated in both studies.

CONCLUSIONS

Galcanezumab had a significant effect in the prevention of eCH attacks but not in cCH. Possible reasons for this discrepancy are discussed.

Cranial autonomic symptoms: prevalence, phenotype and laterality in migraine and two potentially new symptoms

Background

Whilst cranial autonomic symptoms (CAS) are typically associated with trigeminal autonomic cephalalgias (TAC’s), they have also been reported in migraine. Identification and understanding of these symptoms in migraine is important to ensure timely diagnosis and effective management.

Methods

Migraineurs seen in a tertiary headache service between 2014 and 2018 (n = 340): cohort one, and a separate cohort of headache patients seen between 2014-May 2021 reporting voice change, or throat swelling, or both, as CAS were selected (n = 64): cohort two. We performed a service evaluation of our records regarding age, sex, diagnosis, headache and CAS frequency and laterality as acquired from the first consultation, during which a detailed headache history is taken by a headache trained physician.

Results

Cohort 1: Mean age 43 (range 14–94, SD 15). The most common diagnosis was chronic migraine (78%). Median monthly headache frequency was 26 days (IQR 15–75). At least one CAS was reported in 74%, with a median of two (IQR 0–3). The most common were nasal congestion (32%), lacrimation (31%) and aural fullness (25%). Most patients reported their most common headache as unilateral (80%) and with it strictly unilateral CAS (64%). There was a positive association between headache and CAS laterality (χ²₁ = 20.7, P < 0.001), with a positive correlation between baseline headache frequency and number of CAS reported (r = 0.11, P = 0.047). Cohort two: mean age 49 (range 23–83, SD 14). Diagnoses were chronic migraine (50%), chronic cluster headache (11%), undifferentiated continuous lateralised headache (9%), SUNCT/SUNA (8%), hemicrania continua (8%), episodic migraine (8%), episodic cluster headache (3%) and trigeminal neuropathies (3%). Most (89%) described trigeminal distribution pain; 25% involving all three divisions. Throat swelling was reported by 54, voice change by 17, and both by 7. The most common CAS reported were lacrimation (n = 47), facial swelling (n = 45) and rhinorrhoea (n = 37). There was significant agreement between the co-reporting of throat swelling (χ²₁ = 7.59, P = 0.013) and voice change (χ²₁ = 6.49, P = 0.02) with aural fullness.

Conclusions

CAS are common in migraine, are associated with increasing headache frequency and tend to lateralise with headache. Voice change and throat swelling should be recognized as possible parasympathetically-mediated CAS. They may be co-associated and associated with aural fullness, suggesting a broadly somatotopic endophenotype.

History of cluster headache

Objective:

To summarise the history of cluster headache evolving concepts and growing insights.

Background:

Excruciating pain, activation of the parasympathetic nervous system, and circadian rhythmicity characterise cluster headache attacks.

Results:

We find the oldest descriptions of patients suffering from the disorder in case reports of the 17th and 18th centuries. Only in the 19th and early 20th centuries did physicians start hypothesizing its cause. Initially, many researchers suspected the origin of the pain in peripheral nerves or blood vessels. However, eventually, they understood that the cause of the disease lies in the brain. In 1998, Positron emission tomography studies revealed increased activity of the posterior hypothalamus, whose role remains incompletely understood. Only recently have researchers realised that being diseased implies more than dysfunction. Recent studies analysed the consequences of cluster headache for each patient. Many struggle to deal with the disorder even in the absence of pain.

Conclusion:

Physicians have been aware of this type of pain for at least 300 years. Only when researchers studied pathological anatomy and physiology did knowledge accrue. A more comprehensive picture of the disease severity emerged when they also considered its consequences.

Cluster Headache Pathophysiology—A Disorder of Network Excitability?

Patients’ accounts of cluster headache attacks, ictal restlessness, and electrophysiological studies suggest that the pathophysiology involves Aδ-fibre nociceptors and the network processing their input. Continuous activity of the trigeminal autonomic reflex throughout the in-bout period results in central sensitization of these networks in many patients. It is likely that several factors force circadian rhythmicity upon the disease. In addition to sensitization, circadian changes in pain perception and autonomic innervation might influence the excitability of the trigeminal cervical complex. Summation of several factors influencing pain perception might render neurons vulnerable to spontaneous depolarization, particularly at the beginning of rapid drops of the pain threshold (“summation headache”). In light of studies suggesting an impairment of short-term synaptic plasticity in CH patients, we suggest that the physiologic basis of CH attacks might be network overactivity—similarly to epileptic seizures. Case reports documenting cluster-like attacks support the idea of distinct factors being transiently able to induce attacks and being relevant in the pathophysiology of the disorder. A sustained and recurring proneness to attacks likely requires changes in the activity of other structures among which the hypothalamus is the most probable candidate.

The neurobiology of cluster headache

Cluster headache is a primary headache form occurring in paroxysmal excruciatingly severe unilateral head pain attacks usually grouped in periods lasting 1-2months, the cluster periods. A genetic component is suggested by the familial occurrence of the disease but a genetic linkage is yet to be identified. Contemporary activation of trigeminal and cranial parasympathetic systems-the so-called trigemino-parasympathetic reflex-during the headache attacks seem to cause the pain and accompanying oculo-facial autonomic phenomena respectively. At peripheral level, the increased calcitonin gene related peptide (CGRP) plasma levels suggests trigeminal system activation during cluster headache attacks. The temporal pattern of the disease both in terms of circadian rhythmicity and seasonal recurrence has suggested involvement of the hypothalamic biological clock in the pathophysiology of cluster headache. The posterior hypothalamus was investigate as the cluster generator leading to activation of the trigemino-parasympathetic reflex, but the accumulated experience after 20 years of hypothalamic electrical stimulation to treat the condition indicate that this brain region rather acts as pain modulator. Efficacy of monoclonal antibodies to treat episodic cluster headache points to a key role of CGRP in the pathophysiology of the condition.

Cluster Headache: What's New?

Background

Cluster headache is a highly disabling primary headache disorder which is widely described as the most painful condition a human can experience.

Aim

To provide an overview of the clinical characteristics, epidemiology, risk factors, differential diagnosis, pathophysiology and treatment options of cluster headache, with a focus on recent developments in the field.

Methods

Structured review of the literature on cluster headache.

Results

Cluster headache affects approximately one in 1000 of the population. It is characterised by attacks of severe unilateral head pain associated with ipsilateral cranial autonomic symptoms, and the tendency for attacks to occur with circadian and circannual periodicity. The pathophysiology of cluster headache and other primary headache disorders has recently become better understood and is thought to involve the hypothalamus and trigeminovascular system. There is good quality evidence for acute treatment of attacks with parenteral triptans and high flow oxygen; preventive treatment with verapamil; and transitional treatment with oral corticosteroids or greater occipital nerve injection. New pharmacological and neuromodulation therapies have recently been developed.

Conclusion

Cluster headache causes distinctive symptoms, which once they are recognised can usually be managed with a variety of established treatments. Recent pathophysiological understanding has led to the development of newer pharmacological and neuromodulation therapies, which may soon become established in clinical practice.

Current advances in the management of cluster headaches

Introduction: Cluster headache (CH) is probably the most severe idiopathic pain condition, yet its current medical management remains poor.Areas covered: Only repurpose medicines are currently in use for the prevention of CH, partially because the pathophysiology of the condition is still elusive. In this article we performed a systematic review to evaluate the evidence for efficacy of the currently available or emerging treatments for CH.Expert opinion: We found several ongoing randomized clinical trials testing prophylactic treatments for CH and only few for the standard ones. Recent data from randomized trials with monoclonal antibodies targeting the calcitonin gene related peptide pathway (anti-CGRP mAbs) are controversial, although its role in the pathogenesis of the condition is well documented. This inconsistency may depict inadequacies in clinical trial designing. Anti-CGRP mAbs and antagonists of pituitary adenylate cyclase-activating polypeptide (PACAP) along with neuromodulation techniques, are curing the necessary valuable evidence that could illuminate the therapeutical future for cluster headache. Orexin pathway is another attractive target for CH treatment. To improve the evidence for efficacy, we further propose that the design of the clinical trials for CH needs to be radically reviewed to allow more patients to participate.

Cluster headache and TACs: state of the art

Cluster headache (CH), paroxysmal hemicrania (PH), short-lasting unilateral neuralgiform headache attacks (including SUNCT and SUNA), and hemicrania continua (HC) compose the group of trigeminal autonomic cephalalgias (TACs). Here, we review the recent advances in the field and summarize the current knowledge about the origin of these headaches. Similar to the other primary headaches, the pathogenesis is still much obscure. However, advances are being made in both animal models and humans studies. Three structures clearly appear to be crucial in the pathophysiology of TACs: the trigeminal nerve, the facial parasympathetic system, and the hypothalamus. The physiologic and pathologic functioning of each of these elements and their interactions is being progressively clarified, but critical questions are still open.

Updated management of occipital nerve stimulator lead migration: case report of a technical challenge

Electrode migration is a challenge, even with adequate anchoring techniques, due to the high mechanical stress on components of occipital nerve stimulation (ONS) for headache disorders. When a lead displacement of an ONS implant is diagnosed, there are currently different approaches described for its management. Nevertheless current neuromodulation devices are designed like a continuum of components without any intermediate connector, and if a lead displacement is diagnosed, the solution is the complete removal of the electrode from its placement, and its repositioning through an ex-novo procedure. The described technique can allow ONS leads to be revised while minimizing the need to reopen incisions over the IPG, thus improving patients' intraoperative and postoperative discomfort, shortening surgical time and medical costs, reasonably reducing the incidence of infective postoperative complications.

Cluster headache not responsive to sumatriptan: A retrospective study

INTRODUCTION

Subcutaneous sumatriptan, a 5HT_1B/1D agonist, is the most effective drug in cluster headache acute treatment. About 25% of the patients do not respond to subcutaneous sumatriptan; the reasons for this are unknown. In this study, we compare clinical characteristics of cluster headache patients responding and non-responding to subcutaneous sumatriptan.

METHODS

We retrospectively investigated the clinical records of 277 cluster headache patients. Patients reporting repeated satisfactory response to subcutaneous sumatriptan within 15 minutes were considered responders.

RESULTS

Of 206 cluster headache patients who had used subcutaneous sumatriptan (mean age 45.6, 16% females, 48% chronic), 91% were responders, and 9% non-responders. Compared to responders, non-responders had longer and more frequent attacks: 60 (median; IQR 38-90) vs. 100 (60-120) minutes (p = 0.028), 4 (2.5-5) vs. 3 (2-4) attacks/day (p = 0.024). No other difference was found.

CONCLUSIONS

In cluster headache attacks with long duration and high frequency, pain mechanisms not involving 5HT_1B/1D receptors may play a more relevant role.

A proposal for a new headache classification system for general practitioners

We proposes a new method of headache classification, which is simpler for use in general practice and is based on a pathophysiological approach, in preference to the International Classification of Headache Disorders (ICHD) broad classification for headaches. In the ICDH classification, three main categories and numerous sub-categories and divisions are available with a view to addressing the symptoms and the aetiology of headache. However, the ICDH classification system is complex, with its many subdivisions, and it is cumbersome to use. Moreover, it is likely that not all medical professionals are readily familiar with it. A new classification system that is easy to learn and clinically user-friendly is necessary for primary care physicians to diagnose and classify headaches. We believe that our study makes a significant contribution to the literature because we propose a new method of classification for headaches that is based on clinical experience and addresses the pathogenesis of headaches.

Pharmacotherapy for Cluster Headache

Cluster headache is characterised by attacks of excruciating unilateral headache or facial pain lasting 15 min to 3 h and is seen as one of the most intense forms of pain. Cluster headache attacks are accompanied by ipsilateral autonomic symptoms such as ptosis, miosis, redness or flushing of the face, nasal congestion, rhinorrhoea, peri-orbital swelling and/or restlessness or agitation. Cluster headache treatment entails fast-acting abortive treatment, transitional treatment and preventive treatment. The primary goal of prophylactic and transitional treatment is to achieve attack freedom, although this is not always possible. Subcutaneous sumatriptan and high-flow oxygen are the most proven abortive treatments for cluster headache attacks, but other treatment options such as intranasal triptans may be effective. Verapamil and lithium are the preventive drugs of first choice and the most widely used in first-line preventive treatment. Given its possible cardiac side effects, electrocardiogram (ECG) is recommended before treating with verapamil. Liver and kidney functioning should be evaluated before and during treatment with lithium. If verapamil and lithium are ineffective, contraindicated or discontinued because of side effects, the second choice is topiramate. If all these drugs fail, other options with lower levels of evidence are available (e.g. melatonin, clomiphene, dihydroergotamine, pizotifen). However, since the evidence level is low, we also recommend considering one of several neuromodulatory options in patients with refractory chronic cluster headache. A new addition to the preventive treatment options in episodic cluster headache is galcanezumab, although the long-term effects remain unknown. Since effective preventive treatment can take several weeks to titrate, transitional treatment can be of great importance in the treatment of cluster headache. At present, greater occipital nerve injection is the most proven transitional treatment. Other options are high-dose prednisone or frovatriptan.

The spectrum of cluster headache: A case report of 4600 attacks

Introduction

Knowledge of the clinical features of cluster headache is mainly based on retrospective and cross-sectional studies. Here, we present a case of a chronic cluster headache patient who prospectively recorded timing and clinical features of all attacks for 6 years, aiming to describe the clinical spectrum and timing of cluster headache symptoms experienced and to identify daily and/or seasonal rhythmicity.

Methods

Registration of attack timing, duration, associated symptoms and severity was done prospectively on a smartphone application. Pain severity was recorded on a 0–10 scale. Attacks were divided into mild, moderate, severe, and very severe. We analysed diurnal rhythmicity by multimodal Gaussian analysis and spectral analysis.

Results

In total, 4600 attacks were registered (mean duration 39.3 (SD 18.5) min. Mean severity 3.6 (SD 1.28)). Mild attacks accounted for 14.2%, moderate 65.7%, severe 16.9% and very severe 3.2% of all attacks. Nocturnal attacks were more severe than daytime attacks. The number of autonomic symptoms and duration of attacks increased with pain severity. Peak chronorisk (risk of attacks occurring according to hour of day) was at 12.48 in the registration period. Over time, circadian rhythmicity and attack frequency varied.

Conclusion

Clinical characteristics of cluster headache attacks can vary greatly within the individual patient. Clinicians attempting to personalise the administration of preventive treatment should pay notice to the variation over time in diurnal rhythmicity. The recorded self-limiting mild attacks that do not fulfill the ICHD-3 criteria for a cluster headache attack warrant further investigation, as they could hold important information about disease activity.

Primary Headaches

The primary headaches are composed of multiple entities that cause episodic and chronic head pain in the absence of an underlying pathologic process, disease, or traumatic injury. The most common of these are migraine, tension-type headache, and the trigeminal autonomic cephalalgias. This article reviews the clinical presentation, pathophysiology, and treatment of each to help in differential diagnosis. These headache types share many common signs and symptoms, thus a clear understanding of each helps prevent a delay in diagnosis and inappropriate or ineffective treatment. Many of these patients seek dental care because orofacial pain is a common presenting symptom.

Deep brain stimulation for trigeminal autonomic cephalalgias

Introduction: Deep brain stimulation (DBS) of the posterior hypothalamic region (pHyr) has been shown to be efficacious for more than a half of patients suffering from trigeminal autonomic cephalalgias (TACs); nonetheless, controversies about the mechanisms of action and the actual site of stimulation have arisen in recent years.Areas covered: Firstly, a review of the most recent literature on the subject is presented, stressing the critical points that could, in the future, make a difference for optimal management of patients afflicted by these life-threating diseases. Hypothalamic functional anatomy, experimental data and pathophysiological hypotheses are reported.Expert commentary: About 32% of patients who underwent DBS for TACs are pain-free. The determination of the pHyr region seems to be crucial for the generation of pain attack in these pathologies, although other structures are involved in complex mechanisms and circuits that interact with each other. Neurophysiological data, combined with more advanced experimental models, are of primary importance regarding our understanding of what the real target is, and how to overcome the issue of refractory patients.

Diagnosis, pathophysiology, and management of cluster headache

Cluster headache is a trigeminal autonomic cephalalgia characterised by extremely painful, strictly unilateral, short-lasting headache attacks accompanied by ipsilateral autonomic symptoms or the sense of restlessness and agitation, or both. The severity of the disorder has major effects on the patient's quality of life and, in some cases, might lead to suicidal ideation. Cluster headache is now thought to involve a synchronised abnormal activity in the hypothalamus, the trigeminovascular system, and the autonomic nervous system. The hypothalamus appears to play a fundamental role in the generation of a permissive state that allows the initiation of an episode, whereas the attacks are likely to require the involvement of the peripheral nervous system. Triptans are the most effective drugs to treat an acute cluster headache attack. Monoclonal antibodies against calcitonin gene-related peptide, a crucial neurotransmitter of the trigeminal system, are under investigation for the preventive treatment of cluster headache. These studies will increase our understanding of the disorder and perhaps reveal other therapeutic targets.

Cranial parasympathetic activation induces autonomic symptoms but no cluster headache attacks

Background

Low frequency (LF) stimulation of the sphenopalatine ganglion (SPG) may increase parasympathetic outflow and provoke cluster headache (CH) attacks in CH patients implanted with an SPG neurostimulator.

Methods

In a double-blind randomized sham-controlled crossover study, 20 CH patients received LF or sham stimulation for 30 min on two separate days. We recorded headache characteristics, cephalic autonomic symptoms (CAS), plasma levels of parasympathetic markers such as pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) and vasoactive intestinal peptide (VIP), and mechanical detection and pain thresholds as a marker of sensory modulation.

Results

In the immediate phase (0–60 min), 16 (80%) patients experienced CAS after LF stimulation, while nine patients (45%) reported CAS after sham ( p = 0.046). We found no difference in induction of cluster-like attacks between LF stimulation (n = 7) and sham stimulation (n = 5) ( p = 0.724). There was no difference in mechanical detection and pain thresholds, and in PACAP and VIP plasma concentrations between LF and sham stimulation ( p ≥ 0.162).

Conclusion

LF stimulation of the SPG induced autonomic symptoms, but no CH attacks. These data suggest that increased parasympathetic outflow is not sufficient to induce CH attacks in patients.

Study protocol

ClinicalTrials.gov registration number NCT02510729

Advances in the understanding of cluster headache

INTRODUCTION

Cluster headache is the worst primary headache form; it occurs in paroxysmal excruciatingly severe unilateral head pain attacks usually grouped in cluster periods. The familial occurrence of the disease indicates a genetic component but a gene abnormality is yet to be disclosed. Activation of trigeminal afferents and cranial parasympathetic efferents, the so-called trigemino-parasympathetic reflex, can explain pain and accompanying oculo-facial autonomic phenomena. In particular, pain in cluster headache is attributed, at least in part, to the increased CGRP plasma levels released by activated trigeminal system. Posterior hypothalamus was hypothesized to be the cluster generator activating the trigemino-parasympathetic reflex. Efficacy of monoclonal antibodies against CRGP is under investigation in randomized clinical trials. Areas covered: This paper will focus on main findings contributing to consider cluster headache as a neurovascular disorder with an origin from within the brain. Expert commentary: Accumulated evidence with hypothalamic stimulation in cluster headache patients indicate that posterior hypothalamus terminates rather than triggers the attacks. More extensive studies on the genetics of cluster headache are necessary to disclose anomalies behind the increased familial risk of the disease. Results from ongoing clinical trials in cluster headache sufferers using monoclonal antibodies against CGRP will open soon a new era.

Cluster Headache Patients Show Marked Intensity Dependence of Cortical Auditory Evoked Potentials during and outside the Bout

Central serotonergic neurotransmission was assessed using intensity dependence of cortical auditory evoked potentials (IDAP) in cluster headache (CH) patients during both the active and interictal period. In 15 episodic CH patients and 13 controls previously described methods were used and amplitude-stimulus intensity function (ASF) slopes were computed. In the cluster group mean ASF slope was significantly steeper than in the control group both during the active period (1.53 + 0.90 vs. 0.77 + 0.85, P = 0031) and interictally (1.85 + 1.20 vs. 0.77 + 0.85, P = 0012). In the cluster group IDAPs of active and interictal period did not differ significantly ( P = 0378). Duration of the disease or the present bout, distance from the last attack did not correlate with ASF slopes. In conclusion, our results are compatible with decreased level of serotonergic neurotransmission in raphe-cortical pathways. Diminished serotonergic activity in raphe-hypothalamic serotonergic pathways might be hypothesized influencing the activity of hypothalamic neurons and thus play a role in the genesis of cluster headache.

Mechanisms of Autonomic Disturbance in the Face During and Between Attacks of Cluster Headache

Lacrimation and nasal secretion during attacks of cluster headache appear to be due to massive trigeminal-parasympathetic discharge. In addition, the presence of oculo-sympathetic deficit and loss of thermoregulatory sweating and flushing on the symptomatic side of the forehead indicate that the cervical sympathetic pathway to the face is injured in a subgroup of cluster headache patients. In this review, it is argued that a peripheral rather than a central lesion produces signs of cervical sympathetic deficit, probably resulting from compression of the sympathetic plexus around the internal carotid artery. Although trigeminal-parasympathetic discharge appears to be the main trigger for vasodilation during attacks, supersensitivity to neurotransmitters such as vasoactive intestinal polypeptide, together with release of sympathetic vasoconstrictor tone, may boost facial blood flow in patients with cervical sympathetic deficit. In addition, parasympathetic neural discharge may provoke aberrant facial sweating during attacks in patients with cervical sympathetic deficit. Although neither trigeminal-parasympathetic discharge nor cervical sympathetic deficit appears to be the primary trigger for attacks of cluster headache, these autonomic disturbances could contribute to the rapid escalation of pain once the attack begins. For example, a pericarotid inflammatory process that excites trigeminal nociceptors might initiate neurogenic inflammation and trigeminal-parasympathetic vasodilation. To complete the loop, neurogenic inflammation and trigeminal-parasympathetic vasodilation could provoke the release of mast cell products, which aggravate inflammation and intensify trigeminal discharge.

Cluster headache: When to worry? Two case reports

Background The clinical criteria for cluster headache (CH) are included in Chapter 3 of the International Classification of Headache Disorders, 3rd beta edition (ICHD-III). CH may sometimes be secondary to other pathologies. Case reports We report two patients in whom the clinical features of CH initially fulfilled the ICHD-III criteria, but who later presented some radical modifications in headache natural history as a result of a secondary pathology. The first case of CH was secondary to a pontine cavernous angioma and the second to a cerebral venous thrombosis. Conclusion We highlight the importance of clinical modifications of CH that could suggest clinical investigations should be performed or repeated to exclude a secondary pathology in a previously diagnosed cluster headache. Some of the pathological mechanisms of CH and brain lesions are discussed.

Evidence-based treatments for cluster headache

Cluster headache (CH), one of the most painful syndromes known to man, is managed with acute and preventive medications. The brief duration and severity of the attacks command the use of rapid-acting pain relievers. Inhalation of oxygen and subcutaneous sumatriptan are the two most effective acute therapeutic options for sufferers of CH. Several preventive medications are available, the most effective of which is verapamil. However, most of these agents are not backed by strong clinical evidence. In some patients, these options can be ineffective, especially in those who develop chronic CH. Surgical procedures for the chronic refractory form of the disorder should then be contemplated, the most promising of which is hypothalamic deep brain stimulation. We hereby review the pathogenesis of CH and the evidence behind the treatment options for this debilitating condition.

Primary Headache Disorders: Focus on Migraine

Migraine is the most common disabling headache disorder.Most patients with disabling tension-type headache are likely to have migraine and accordingly respond to treatments efficacious in migraine.Individuals are genetically predisposed to experiencing recurrent migraine.Evidence supports migraine to be a primarily neural and not vascular mediated disorder.1-2% of the population have chronic daily headache associated with acute-relief medication overuse; the majority are migraineurs.The presence of acute-relief medication overuse renders preventative medication less adequately efficacious.

Evaluation of the new ICHD-III beta cluster headache criteria

Aim

In the revised criteria of the International Classification of Headache Disorders (ICHD-III beta) the following items are added to the diagnostic criteria of cluster headache: ipsilateral sensation of fullness in the ear and ipsilateral forehead/facial flushing. We evaluated the possible additional value of these symptoms for diagnosing cluster headache.

Methods

In this cross-sectional cohort study of (potential) cluster headache patients we investigated these additional symptoms using a Web-based questionnaire. Patients not fulfilling the ICHD-II criteria for cluster headache but fulfilling the ICHD-III beta criteria were interviewed.

Results

Response rate was 916/1138 (80.5%). Of all 573 patients with cluster headache according to ICHD-II criteria, 192 (33.5%) reported ipsilateral ear fullness and 113 (19.7%) facial flushing during attacks. There was no difference in reporting ipsilateral ear fullness and facial flushing between patients who received a diagnosis of cluster headache and patients who did not. None of the patients who did not fulfill all ICHD-II criteria could be categorized as cluster headache according to the ICHD-III beta criteria.

Conclusion

The results of this study do not support the addition of ear fullness and facial flushing to the new ICHD-III beta criteria.

Trigeminal autonomic cephalalgias: beyond the conventional treatments

The trigeminal autonomic cephalalgias include cluster headache, paroxysmal hemicrania, short-lasting unilateral neuralgiform headache attacks, and hemicrania continua. While the majority responds to conventional pharmacological treatments, a small but significant proportion of patients are intractable to these treatments. In these cases, alternative choices for these patients include oral and injectable drugs, lesional or resectional surgery, and neurostimulation. The evidence base for conventional treatments is limited, and the evidence for those used beyond convention is more so. At present, the most evidence exists for nerve blocks, deep brain stimulation, occipital nerve stimulation, sphenopalatine ganglion stimulation in chronic cluster headache, and microvascular decompression of the trigeminal nerve in short-lasting unilateral neuralgiform headache attacks.

Temporal retinal nerve fibre layer thinning in cluster headache patients detected by optical coherence tomography

BACKGROUND

The exact pathophysiology of cluster headache (CH) is still not fully clarified. Various studies confirmed changes in ocular blood flow during CH attacks. Furthermore, vasoconstricting medication influences blood supply to the eye. We investigated the retina of CH patients for structural retinal alterations with optical coherence tomography (OCT), and how these changes correlate to headache characteristics, oxygen use and impaired visual function.

METHODS

Spectral domain OCT of 107 CH patients - 67 episodic, 35 chronic, five former chronic sufferers - were compared to OCT from 65 healthy individuals. Visual function tests with Sloan charts and a substantial ophthalmologic examination were engaged.

RESULTS

Reduction of temporal and temporal-inferior retinal nerve fibre layer (RNFL) thickness was found in both eyes for CH patients with a predominant thinning on the headache side in the temporal-inferior area. Chronic CH patients revealed thinning of the macula compared to episodic suffers and healthy individuals. Bilateral thinning of temporal RNFL was also found in users of 100% oxygen compared to non-users and healthy controls. Visual function did not differ between patients and controls.

DISCUSSION

Our OCT findings show a systemic effect causing temporal retinal thinning in both eyes of CH patients possibly due to attack-inherent or medication-induced frequent bilateral vessel diameter changes. The temporal retina with its thinly myelinated parvo-cellular axons and its more susceptible vessels for the vasoconstricting influence of oxygen inhalation seems to be predisposed for tissue damage-causing processes related to CH.

Strictly unilateral headaches: considerations of a clinician

The aim of the lecture is to draw attention to the role that clinical practice and clinical observation have had in stimulating research on the pathophysiology of cluster headache (CH) and other trigeminal autonomic cephalalgias (TACs). The symptoms of cluster headache-in particular the typical circadian periodicity of the headaches and the seasonal recurrence of cluster periods-were fundamental in shifting attention away from peripheral pathogenetic hypotheses to the idea that cluster headache could have a central origin. Initially, solid neuroendocrinological data pointed to hypothalamic involvement. For example, CH patients were shown to have alterations in biorhythms. Subsequently, modern functional neuroimaging techniques were able to demonstrate that the homolateral posterior hypothalamus is activated during TAC headaches, so implicating this region in TAC pathogenesis. It is known that the hypothalamus has a modulatory effect on nociceptive and autonomic pathways, particularly on the nociceptive trigeminovascular system. Future research should clarify whether the hypothalamus is the generator of TAC headaches, or whether it is activated in response to an alteration of the homeostatic equilibrium between limbic emotional-affective components and autonomic-nociceptive components modulated by the hypothalamus.

Neuromodulation of chronic headaches: position statement from the European Headache Federation

The medical treatment of patients with chronic primary headache syndromes (chronic migraine, chronic tension-type headache, chronic cluster headache, hemicrania continua) is challenging as serious side effects frequently complicate the course of medical treatment and some patients may be even medically intractable. When a definitive lack of responsiveness to conservative treatments is ascertained and medication overuse headache is excluded, neuromodulation options can be considered in selected cases. Here, the various invasive and non-invasive approaches, such as hypothalamic deep brain stimulation, occipital nerve stimulation, stimulation of sphenopalatine ganglion, cervical spinal cord stimulation, vagus nerve stimulation, transcranial direct current stimulation, repetitive transcranial magnetic stimulation, and transcutaneous electrical nerve stimulation are extensively published although proper RCT-based evidence is limited. The European Headache Federation herewith provides a consensus statement on the clinical use of neuromodulation in headache, based on theoretical background, clinical data, and side effect of each method. This international consensus further gives recommendations for future studies on these new approaches. In spite of a growing field of stimulation devices in headaches treatment, further controlled studies to validate, strengthen and disseminate the use of neurostimulation are clearly warranted. Consequently, until these data are available any neurostimulation device should only be used in patients with medically intractable syndromes from tertiary headache centers either as part of a valid study or have shown to be effective in such controlled studies with an acceptable side effect profile.

Pathophysiology of Migraine

Migraine is a serious health problem which impair quality of life. It is the second most common primary headache that affects approximately more than %10 people in general population. Migraine pathophysiology is still unclear. Increasing results of studies suggest to migraine pathophysiology is related with primary neuronal mechanisms. Migraine pain starts in which region of brain and what brain regions are activated in different stages is unenlightened. There is evidences that growing number of studies which using new imaging techniques as positron emission tomography (PET) and functional magnetic resonans imaging (fMRI) show that migraine and cluster headaches are related with neuronal structures and vasodilatation. There are four phases to a migraine. The prodrome phase, aura, the attack, and the postdrome phase. Some datas obtained from last ten years indicate that cortical excitability has increased in interictal phase too. For many years, studies in rodents show trgimenial nerve is activated and it leads to vasodilatation and neurogenic inflammation in the headache phase. Although the majority of patients encountered in clinical practice are migraine without aura or chronic migraine, experimental studies of the migraine pathophysiology are focusing on the aura model which is used cortical spreading depression.

Pain referral patterns of the C1 to C3 nerves: implications for headache disorders

The cervical nerves may play a significant role in primary headache disorders. We reviewed the patterns of pain evoked by stimulation of the first 3 cervical nerves (C1-C3) in 10 patients with chronic occipital pain, 6 of whom also had migraine. Stimulation at the C1 level evoked periorbital and frontal pain in 6 of 6 patients with migraine but evoked occipital or cervical pain in those without migraine. C2 and C3 stimulation resulted in occipital or cervical pain in all patients. The C1 nerve may have an important sensory function in headache disorders that have orbital and frontal pain as a prominent feature.

Neurostimulation in cluster headache: A review of current progress

Purpose of review

Neurostimulation has emerged as a viable treatment for intractable chronic cluster headache. Several therapeutic strategies are being investigated including stimulation of the hypothalamus, occipital nerves and sphenopalatine ganglion. The aim of this review is to provide an overview of the rationale, methods and progress for each of these.

Latest findings

Results from a randomized, controlled trial investigating sphenopalatine ganglion stimulation have just been published. Reportedly the surgery is relatively simple and it is apparently the only therapy that provides relief acutely.

Summary

The rationale behind these therapies is based on growing evidence from clinical, hormonal and neuroimaging studies. The overall results are encouraging, but unfortunately not all patients have benefited. All the mentioned therapies require weeks to months of stimulation for a prophylactic effect to occur, suggesting brain plasticity as a possible mechanism, and only stimulation of the sphenopalatine ganglion has demonstrated an acute, abortive effect. Predictors of effect for all modes of neurostimulation still need to be identified and in the future, the least invasive and most effective strategy must be preferred as first-line therapy for intractable chronic cluster headache.

Paraventricular hypothalamic regulation of trigeminovascular mechanisms involved in headaches

While functional imaging and deep brain stimulation studies point to a pivotal role of the hypothalamus in the pathophysiology of migraine and trigeminal autonomic cephalalgias, the circuitry and the mechanisms underlying the modulation of medullary trigeminovascular (Sp5C) neurons have not been fully identified. We investigated the existence of a direct anatomo-functional relationship between hypothalamic excitability disturbances and modifications of the activities of Sp5C neurons in the rat. Anterograde and retrograde neuronal anatomical tracing, intrahypothalamic microinjections, extracellular single-unit recordings of Sp5C neurons, and behavioral trials were used in this study. We found that neurons of the paraventricular nucleus of the hypothalamus (PVN) send descending projections to the superior salivatory nucleus, a region that gives rise to parasympathetic outflow to cephalic and ocular/nasal structures. PVN cells project also to laminae I and outer II of the Sp5C. Microinjections of the GABAA agonist muscimol into PVN inhibit both basal and meningeal-evoked activities of Sp5C neurons. Such inhibitions were reduced in acutely restrained stressed rats. GABAA antagonist gabazine infusions into the PVN facilitate meningeal-evoked responses of Sp5C neurons. PVN injections of the neuropeptide pituitary adenylate cyclase activating peptide (PACAP38) enhance Sp5C basal activities, whereas the antagonist PACAP6-38 depresses all types of Sp5C activities. 5-HT1B/D receptor agonist naratriptan infusion confined to the PVN depresses both basal and meningeal-evoked Sp5C activities. Our findings suggest that paraventricular hypothalamic neurons directly control both spontaneous and evoked activities of Sp5C neurons and could act either as modulators or triggers of migraine and/or trigeminal autonomic cephalalgias by integrating nociceptive, autonomic, and stress processing mechanisms.

Cluster-tic syndrome as the initial manifestation of multiple sclerosis

We report the case of a patient diagnosed as having cluster-tic syndrome as the initial manifestation of multiple sclerosis (MS). The patient’s headache bouts improved after treatment with antiepileptic drugs, steroids, and beta-interferon. Magnetic resonance imaging (MRI) scans showed a pontine demyelinating lesion involving the area of the trigeminal root inlet and main sensory nucleus. Neurophysiological studies correlated well with MRI lesions. The association between cluster-tic syndrome and MS is an exception, and the mechanism of the pain is still unknown; therefore, this case might suggest a pathophysiological relationship between the trigeminal main sensory nucleus and cluster-tic syndrome.

The lack of peripheral pathology in migraine headache

This article reviews the baffling problem of the pathophysiology behind a peripheral genesis of migraine pain--or more particularly the baffling problem of its absence. I examine a number of pathophysiological states and the effector mechanisms for these states and find most of them very plausible and that they are all supported by abundant evidence. However, this evidence is mostly indirect; to date the occurrence of any of the presumed pathological states has not been convincingly demonstrated. Furthermore, there is little evidence of increased trigeminal sensory traffic into the central nervous system during a migraine attack. The article also examines a number of observations and experimental programs used to bolster a theory of peripheral pathology and suggests reasons why they may in fact not bolster it. I suggest that a pathology, if one exists, may be in the brain and even that it may not be a pathology at all. Migraine headache might just happen because of random noise in an exquisitely sensitive and complex network. The article suggests an experimental program to resolve these issues.