Cluster headache pathophysiology: What we have learned from advanced neuroimaging

Background

Although remarkable progress has been achieved in understanding cluster headache (CH) pathophysiology, there are still several gaps about the mechanisms through which independent subcortical and cortical brain structures interact with each other. These gaps could be partially elucidated by structural and functional advanced neuroimaging investigations.

Objective

Although we are aware that substantial achievements have come from preclinical, neurophysiological, and biochemical experiments, the present narrative review aims to summarize the most significant findings from structural, microstructural, and functional neuroimaging investigations, as well as the consequent progresses in understanding CH pathophysiological mechanisms, to achieve a comprehensive and unifying model.

Results

Advanced neuroimaging techniques have contributed to overcoming the peripheral hypothesis that CH is of cavernous sinus pathology, in transitioning from the pure vascular hypothesis to a more comprehensive trigeminovascular model, and, above all, in clarifying the role of the hypothalamus and its connections in the genesis of CH.

Conclusion

Altogether, neuroimaging findings strongly suggest that, beyond the theoretical model of the “pain matrix,” the model of the “neurolimbic pain network” that is accepted in migraine research could also be extended to CH. Indeed, although the hypothalamus’ role is undeniable, the genesis of CH attacks is complex and seems to not be just the result of a single “generator.” Cortical‐hypothalamic‐brainstem functional interconnections that can switch between out‐of‐bout and in‐bout periods, igniting the trigeminovascular system (probably by means of top‐down mechanisms) and the consensual trigeminal autonomic reflexes, may represent the “neuronal background” of CH.

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.

Caffeine and Primary (Migraine) Headaches-Friend or Foe?

Background: The actions of caffeine as an antagonist of adenosine receptors have been extensively studied, and there is no doubt that both daily and sporadic dietary consumption of caffeine has substantial biological effects on the nervous system. Caffeine influences headaches, the migraine syndrome in particular, but how is unclear. Materials and Methods: This is a narrative review based on selected articles from an extensive literature search. The aim of this study is to elucidate and discuss how caffeine may affect the migraine syndrome and discuss the potential pathophysiological pathways involved. Results: Whether caffeine has any significant analgesic and/or prophylactic effect in migraine remains elusive. Neither is it clear whether caffeine withdrawal is an important trigger for migraine. However, withdrawal after chronic exposure of caffeine may cause migraine-like headache and a syndrome similar to that experienced in the prodromal phase of migraine. Sensory hypersensitivity however, does not seem to be a part of the caffeine withdrawal syndrome. Whether it is among migraineurs is unknown. From a modern viewpoint, the traditional vascular explanation of the withdrawal headache is too simplistic and partly not conceivable. Peripheral mechanisms can hardly explain prodromal symptoms and non-headache withdrawal symptoms. Several lines of evidence point at the hypothalamus as a locus where pivotal actions take place. Conclusion: In general, chronic consumption of caffeine seems to increase the burden of migraine, but a protective effect as an acute treatment or in severely affected patients cannot be excluded. Future clinical trials should explore the relationship between caffeine withdrawal and migraine, and investigate the effects of long-term elimination.

Ventral tegmental area deep brain stimulation for chronic cluster headache: Effects on cognition, mood, pain report behaviour and quality of life

Background

Deep brain stimulation in the ventral tegmental area (VTA-DBS) has provided remarkable therapeutic benefits in decreasing headache frequency and severity in patients with medically refractory chronic cluster headache (CH). However, to date the effects of VTA-DBS on cognition, mood and quality of life have not been examined in detail.

Methods

The aim of the present study was to do so in a case series of 18 consecutive patients with cluster headache who underwent implantation of deep brain stimulation electrodes in the ventral tegmental area. The patients were evaluated preoperatively and after a mean of 14 months of VTA-DBS on tests of global cognition (Mini Mental State Examination), intelligence (Wechsler Abbreviated Scale of Intelligence), verbal memory (California Verbal Learning Test-II), executive function (Delis–Kaplan Executive Function System), and attention (Paced Auditory Serial Addition Test). Depression (Beck Depression Inventory and Hospital Anxiety and Depression Rating Scale-D), anxiety (Hospital Anxiety and Depression Rating Scale-A), apathy (Starkstein Apathy Scale), and hopelessness (Beck Hopelessness Scale) were also assessed. Subjective pain experience (McGill Pain Questionnaire), behaviour (Pain Behaviour Checklist) and quality of life (Short Form-36) were also evaluated at the same time points.

Results

VTA-DBS resulted in significant improvement of headache frequency (from a mean of five to two attacks daily, p < .001) and severity (from mean Verbal Rating Scale [VRS] of 10 to 7, p < .001) which was associated with significant reduction of anxiety (from mean HADS-A of 11.94 to 8.00, p < .001) and help-seeking behaviours (from mean PBC of 4.00 to 2.61, p < .001). VTA-DBS did not produce any significant change to any tests of cognitive function and any other outcome measures (BDI, HADS-D, SAS, BHS, McGill Pain Questionnaire, Short Form-36).

Conclusion

We confirm the efficacy of VTA-DBS in the treatment of medically refractory chronic cluster headache. The reduction of headache frequency and severity was associated with a significant reduction of anxiety. Furthermore, the result suggests that VTA-DBS for chronic cluster headache improves pain-related help-seeking behaviours and does not produce any change in cognition.

Migraine and cluster headache - the common link

Although clinically distinguishable, migraine and cluster headache share prominent features such as unilateral pain, common pharmacological triggers such glyceryl trinitrate, histamine, calcitonin gene-related peptide (CGRP) and response to triptans and neuromodulation. Recent data also suggest efficacy of anti CGRP monoclonal antibodies in both migraine and cluster headache. While exact mechanisms behind both disorders remain to be fully understood, the trigeminovascular system represents one possible common pathophysiological pathway and network of both disorders. Here, we review past and current literature shedding light on similarities and differences in phenotype, heritability, pathophysiology, imaging findings and treatment options of migraine and cluster headache. A continued focus on their shared pathophysiological pathways may be important in paving future treatment avenues that could benefit both migraine and cluster headache patients.

Sensory function in cluster headache: an observational study comparing the symptomatic and asymptomatic sides

BACKGROUND

Based on inconsistent sensory alterations demonstrated in cluster headache (CH), the aim of this study was to determine whether patients with CH develop sensory changes in the symptomatic side compared to the asymptomatic side.

METHODS

Quantitative sensory testing (QST), including pressure pain threshold (PPT), tactile detection threshold (TDT), prick detection threshold (PDT), and two-point detection threshold (2PDT), was evaluated in 16 patients (seven women; age 41.9±6.8 years) with CH. Test sites included the first, second, and third divisions of the trigeminal nerve, cervical spine, and thenar eminence in the symptomatic and asymptomatic sides.

RESULTS

The symptomatic side, compared to the asymptomatic side, presented significantly decreased PPT in the first (P=0.011; 423.81±174.05 kPa vs 480.13±214.99 kPa) and second (P=0.023; 288.88±140.80 kPa vs 326.38±137.33 kPa) divisions of the trigeminal nerve, significantly increased TDT in the first (P=0.002; 2.44±0.40 vs 1.74±0.24) and second (P=0.016; 1.92±0.34 vs 1.67±0.09) divisions, and increased 2PDT in the first division (P=0.004; 18.13±4.70 mm vs 15.0±4.92 mm) and neck (P=0.007; 45.31±20.65 mm vs 38.44±16.10 mm).

CONCLUSION

These results support the prior evidence suggesting a specific pattern of alteration of sensory function with alterations in the symptomatic side compared to the asymptomatic side.

The Neuropharmacology of Cluster Headache and other Trigeminal Autonomic Cephalalgias

Trigeminal autonomic cephalalgias (TACs) are a group of primary headaches including cluster headache (CH), paroxysmal hemicrania (PH) and short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT). Another form, hemicrania continua (HC), is also included this group due to its clinical and pathophysiological similarities. CH is the most common of these syndromes, the others being infrequent in the general population. The pathophysiology of the TACs has been partly elucidated by a number of recent neuroimaging studies, which implicate brain regions associated with nociception (pain matrix). In addition, the hypothalamic activation observed in the course of TAC attacks and the observed efficacy of hypothalamic neurostimulation in CH patients suggest that the hypothalamus is another key structure. Hypothalamic activation may indeed be involved in attack initiation, but it may also lead to a condition of central facilitation underlying the recurrence of pain episodes. The TACs share many pathophysiological features, but are characterised by differences in attack duration and frequency, and to some extent treatment response. Although alternative strategies for the TACs, especially CH, are now emerging (such as neurostimulation techniques), this review focuses on the available pharmacological treatments complying with the most recent guidelines. We discuss the clinical efficacy and tolerability of the currently used drugs. Due to the low frequency of most TACs, few randomised controlled trials have been conducted. The therapies of choice in CH continue to be the triptans and oxygen for acute treatment, and verapamil and lithium for prevention, but promising results have recently been obtained with novel modes of administration of the triptans and other agents, and several other treatments are currently under study. Indomethacin is extremely effective in PH and HC, while antiepileptic drugs (especially lamotrigine) appear to be increasingly useful in SUNCT. We highlight the need for appropriate studies investigating treatments for these rare, but lifelong and disabling conditions.

Cluster belly: a variant of irritable bowel syndrome

Cluster headache (CH) and irritable bowel syndrome (IBS) are pain disorders that possess relationships with circadian rhythms. However, they have not been compared to assess similarities that could yield pathophysiologic insights. A young male adult with periodic episodes of abdominal pain highly reminiscent of CH is described. Since childhood, he experienced severe attacks featuring excruciating, abdominal pain accompanied by prominent restlessness, lasting 30-120 minutes, occurring in the evening and in discrete 2- to 8-week periods, interspersed with remissions where typical triggers did not lead to attacks. Although all of the patient's symptoms fell within the spectrum of IBS, the semiology was highly evocative of CH, based on the attack duration, restlessness, periodicity, and selective vulnerability to particular triggers only during attack periods. A subset of patients thought to have IBS may feature similar attack profiles and could suggest the importance of the hypothalamus in its pathophysiology, akin to CH.

Insomnia and periodicity of headache in an arctic cluster headache population

OBJECTIVE

To assess the prevalence of chronic insomnia and the periodicity of headache attacks in an Arctic cluster headache population.

BACKGROUND

Cluster headache is a sleep-related disorder, and attacks have both circadian and circannual rhythmicity.

METHODS

Through a retrospective hospital chart review, we identified all subjects diagnosed with episodic cluster headache (ICD-10 G 44.0) at the Neurological Departments in Northern Norway (located north of 66°33'N) between January 1, 2000 and December 31, 2010. Patients with a confirmed diagnosis (ICHD-2) received a comprehensive questionnaire covering demographic data, clinical characteristics, sleep, and periodicity of attacks.

RESULTS

A total of 196 subjects were registered, and 178 received the questionnaire. The response rate was 88/178 (49%). Fifty-eight men (aged 49.2 ± 13.6) and 12 women (aged 49.7 ± 15.5) were included. Forty percent of the responders suffered from chronic insomnia (Diagnostic and Statistical Manual of Mental Disorders 4th edition). Forty-nine percent of the responders and 42% of the non-responders were shift workers, which is much higher than compared with the general population (24%). Insomnia was significantly associated with shift work and experiencing longer-lasting cluster bouts. One third attributed their insomnia to the cluster headache. Thirty-seven percent reported a seasonal predilection of the cluster periods, and 58% a diurnal periodicity of attacks. Eighty percent often or always had headache attacks during sleep, the most frequent time interval being at 12:00-4:00 am. Shift workers were significantly more likely to see lack of sleep as a cluster attack trigger than daytime workers.

CONCLUSIONS

Chronic insomnia and shift work seem to be common among Arctic cluster headache patients. The small number of subjects included in this study implies that conclusions should be drawn with caution, but the findings support the idea of cluster headache as a circadian rhythm disorder.

Hypothalamic dopaminergic stimulation in cluster headache

BACKGROUND

Cluster headache is associated with structural abnormalities of the hypothalamus. We were interested in the association of cluster headache with endocrinological functional abnormalities. Therefore, we applied the apomorphine challenge test, which is a specific test of hypothalamic dopaminergic activation.

METHODS

We enrolled 13 patients with cluster headache outside the bout and without medication. They were stimulated with 0.005 mg/kg of body weight subcutaneous apomorphine hydrochloride. After 45 and 60 minutes, growth hormone (GH), prolactin and cortisol were measured. The test was also applied to 14 sex- and age-matched healthy control subjects.

RESULTS

There were significantly higher GH levels in healthy subjects as compared to cluster headache patients 45 minutes after injection (10.8 ± 10.8 versus 4.4 ± 7.4 ng/ml; P  = 0.038). Only in cluster headache, the GH level after 60 minutes was not significantly different from the baseline. The levels of prolactin and cortisol did not show any significant differences between cluster headache patients and in healthy subjects.

DISCUSSION

Our data suggest that cluster headache is associated with an impaired dopaminergic stimulation. This finding supports the body of evidence that cluster headache is associated with a functional abnormality of the hypothalamus and that this association is a primary (i.e. idiopathic) and not a secondary phenomenon during the bout.

Clinical profile of cluster headaches in China - a clinic-based study

BACKGROUND

The clinical profile of cluster headache in Chinese patients have not been fully studied.

METHODS

The classification and clinical features of 120 consecutive patients with cluster headache (105 males, 15 females; mean age, 34.9 ± 10.5 years) visiting at International Headache Center from May 2010 to August 2012 were analyzed.

RESULTS

Patients came from 16 different regions of China. Mean age at onset of cluster headache was 26.7 ± 10.9 years. Only 13 patients (10.8%) had previously been diagnosed with cluster headache. Mean time to diagnosis from first symptoms was 8.2 ± 7.1 years (range, 0-35 years). Chronic cluster headache was observed in only 9 patients (7.5%). The most commonly reported location of cluster headache was temporal region (75.0%), followed by retro-orbital region (68.3%), forehead (32.5%), vertex (32.5%) and occipital (22.5%). Lacrimation was the most consistently reported autonomic feature (72.5%). During acute attacks, 60.0% of patients experienced nausea, and 41.7% experienced photophobia and 40.8% experienced phonophobia. In addition, 38.3% reported restless behavior and 45.8% reported that physical activity exacerbated the pain. None of patients experienced visual or other kinds of aura symptoms before cluster attacks. We found that 38.3% of patients had <1 cluster period and 35.8% for 1-2 cluster periods per year with these periods occurring less frequently during the summer than during other seasons. Cluster duration was 1-2 months in 32.5% of patients. During cluster periods, 73.3% of patients had 1-2 attacks per day, and 39.2% experienced cluster attacks ranging in duration from 1 h to less than 2 h. The duration of attacks were 1.5 (1-2.25) hours for males and 1.5 (1-3) for females respectively. The World Health Organization quality of life-8 questionnaire showed that cluster headache reduced life quality.

CONCLUSIONS

Compared to Western patients, Chinese patients showed a relatively low prevalence of chronic cluster headaches, pain sites mainly focused on areas distributed by the first division of the trigeminal nerve, a low frequency of restlessness and absent aura. These clinical features may be more common in Eastern populations, including mainland Chinese, Japanese and Taiwanese patients, than in Western patients.

Cluster-like headache and a cystic hypothalamic tumour as first presentation of sarcoidosis

INTRODUCTION

Sarcoidosis is a granulomatous, multisystem inflammatory disease of unknown cause, which presents with a wide variety of symptoms. We describe a rare case of a newly diagnosed sarcoidosis, with cluster-like headache as a presenting symptom.

CASE

A 31-year-old man presented with cluster headache with a cystic lesion in the hypothalamus. A non-caseating granuloma consistent with the diagnosis sarcoidosis was found at biopsy. Pulmonary involvement was confirmed on positron electron tomography-computed tomography (PET-CT). Treatment with prednisone led to regression of the hypothalamic lesion. Headache attacks did not recur.

DISCUSSION

Cluster-like headache with a cystic hypothalamic lesion as first presentation of sarcoidosis has never been reported. Their possible relationship seems to underline the role of the hypothalamus in the central pain-regulatory areas in the brain, but is not undisputed. This case clearly demonstrates once again the relevance of neuroimaging in new-onset cluster-like headache.