Safety and efficacy of sphenopalatine ganglion stimulation for chronic cluster headache: a double-blind, randomised controlled trial

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

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

Sphenopalatine ganglion stimulation: a comprehensive evaluation across diseases in randomized controlled trials

Background

Current literature extensively covers the use of sphenopalatine ganglion stimulation (SPGs) in treating a broad spectrum of medical conditions, such as allergic rhinitis, cluster headaches, and strokes. Nevertheless, a discernible gap in the systematic organization and analysis of these studies is evident. This paper aims to bridge this gap by conducting a comprehensive review and analysis of existing literature on SPGs across various medical conditions.

Methods

This study meticulously constructed a comprehensive database through systematic computerized searches conducted on PubMed, Embase, CNKI, Wanfang, VIP, and CBM up to May 2022. The inclusion criteria encompassed randomized controlled trials (RCTs) published in either Chinese or English, focusing on the therapeutic applications of SPGs for various medical conditions. Both qualitative and quantitative outcome indicators were considered eligible for inclusion.

Results

This comprehensive study reviewed 36 publications, comprising 10 high-quality, 23 medium-quality, and three low-quality articles. The study investigated various diseases, including allergic rhinitis (AR), ischemic strokes (IS), cluster headache (CH), primary trigeminal neuralgia (PTN), pediatric chronic secretory otitis (PCSO), refractory facial paralysis (RFP), chronic tension-type headache (CTTH), as well as the analysis of low-frequency sphenopalatine ganglion stimulation (LF-SPGs) in chronic cluster headache (CCH) and the impact of SPGs on Normal nasal cavity function (NNCF). SPGs demonstrate efficacy in the treatment of AR. Regarding the improvement of rhinoconjunctivitis quality of life questionnaire (RQLQ) scores, SPGs are considered the optimal intervention according to the SUCRA ranking. Concerning the improvement in Total Nasal Symptom Score (TNSS), Conventional Acupuncture Combined with Tradiational Chinese Medicine (CA-TCM) holds a significant advantage in the SUCRA ranking and is deemed the best intervention. In terms of increasing Effective Rate (ER), SPGs outperformed both conventional acupuncture (CA) and Western Medicine (WM; P < 0.05). In the context of SPGs treatment for IS, the results indicate a significant improvement in the 3-month outcomes, as evaluated by the modified Rankin Scale (mRS) in the context of Cerebral Cortical Infarction (CCI; P < 0.05). In the treatment of CH with SPGs, the treatment has been shown to have a statistically significant effect on the relief and disappearance of headaches (P < 0.05). The impact of SPGs on NNCF reveals statistically significant improvements (P < 0.05) in nasal airway resistance (NAR), nasal cavity volume (NCV), exhaled nitric oxide (eNO), substance P (SP), vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY). SPGs treatments for PCSO, RFP, and CTTH, when compared to control groups, yielded statistically significant results (P < 0.05).

Conclusion

SPGs demonstrate significant effectiveness in the treatment of AR, IS, and CH. Effective management of CCH may require addressing both autonomic dysregulation and deeper neural pathways. However, additional high-quality research is essential to clarify its effects on NNCF, PTN, PCSO, RFP, and CTTH.

Systematic Review Registration

PROSPERO, identifier CRD42021252073, https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=312429.

Neuromodulation for Craniofacial Pain and Headaches

Headaches and facial pain are highly prevalent diseases but are often difficult to treat. Though there have been significant advances in medical management, many continue to suffer from refractory pain. Neuromodulation has been gaining interest for its therapeutic purposes in many chronic pain conditions, including headaches and facial pain. There are many potential targets of neuromodulation for headache and facial pain, and some have more robust evidence in favor of their use than others. Despite the need for more high-quality research, the available evidence for the use of neuromodulation in treating headaches and facial pain is promising. Considering the suffering that afflicts patients with intractable headache, neuromodulation may be an appropriate tool to improve not only pain but also disability and quality of life.

A prospective open label 2-8 year extension of the randomised controlled ICON trial on the long-term efficacy and safety of occipital nerve stimulation in medically intractable chronic cluster headache

BACKGROUND

We demonstrated in the randomised controlled ICON study that 48-week treatment of medically intractable chronic cluster headache (MICCH) with occipital nerve stimulation (ONS) is safe and effective. In L-ICON we prospectively evaluate its long-term effectiveness and safety.

METHODS

ICON participants were enrolled in L-ICON immediately after completing ICON. Therefore, earlier ICON participants could be followed longer than later ones. L-ICON inclusion was stopped after the last ICON participant was enrolled in L-ICON and followed for ≥2 years by completing six-monthly questionnaires on attack frequency, side effects, subjective improvement and whether they would recommend ONS to others. Primary outcome was the change in mean weekly attack frequency 2 years after completion of the ICON study compared to baseline. Missing values for log-transformed attack-frequency were imputed for up to 5 years of follow-up. Descriptive analyses are presented as (pooled) geometric or arithmetic means and 95% confidence intervals.

FINDINGS

Of 103 eligible participants, 88 (85%) gave informed consent and 73 (83%) were followed for ≥2 year, 61 (69%) ≥ 3 year, 33 (38%) ≥ 5 years and 3 (3%) ≥ 8.5 years. Mean (±SD) follow-up was 4.2 ± 2.2 years for a total of 370 person years (84% of potentially 442 years). The pooled geometric mean (95% CI) weekly attack frequency remained considerably lower after one (4.2; 2.8-6.3), two (5.1; 3.5-7.6) and five years (4.1; 3.0-5.5) compared to baseline (16.2; 14.4-18.3). Of the 49/88 (56%) ICON ≥50% responders, 35/49 (71%) retained this response and 15/39 (38%) ICON non-responders still became a ≥50% responder for at least half the follow-up period. Most participants (69/88; 78% [0.68-0.86]) reported a subjective improvement from baseline at last follow-up and 70/88 (81% [0.70-0.87]) would recommend ONS to others. Hardware-related surgery was required in 44/88 (50%) participants in 112/122 (92%) events (0.35 person-year-1 [0.28-0.41]). We didn't find predictive factors for effectiveness.

INTERPRETATION

ONS is a safe, well-tolerated and long-term effective treatment for MICCH.

FUNDING

The Netherlands Organisation for Scientific Research, the Dutch Ministry of Health, the NutsOhra Foundation from the Dutch Health Insurance Companies, and Medtronic.

Neuromodulation for the Sphenopalatine Ganglion-a Narrative Review

PURPOSE OF REVIEW

To provide an integrated overview of the current state of knowledge of neuromodulation for the sphenopalatine ganglion (SPG) by reviewing relevant and significant literature.

RECENT FINDINGS

There are several case reports and clinical trials evaluating neuromodulation for the SPG. We identified two blinded, randomized clinical trials for patients with chronic cluster headache. The randomized trials and additional studies demonstrated the long-term safety, efficacy, and cost-effectiveness of neuromodulation for the SPG. Recent studies in Europe and the USA suggest that SPG neuromodulation is a novel modality with clinical importance for treating acute cluster headaches and reducing the frequency of attacks.

European Academy of Neurology guidelines on the treatment of cluster headache

BACKGROUND AND PURPOSE

Cluster headache is a relatively rare, disabling primary headache disorder with a major impact on patients' quality of life. This work presents evidence-based recommendations for the treatment of cluster headache derived from a systematic review of the literature and consensus among a panel of experts.

METHODS

The databases PubMed (Medline), Science Citation Index, and Cochrane Library were screened for studies on the efficacy of interventions (last access July 2022). The findings in these studies were evaluated according to the recommendations of the European Academy of Neurology, and the level of evidence was established using GRADE (Grading of Recommendations Assessment, Development, and Evaluation).

RECOMMENDATIONS

For the acute treatment of cluster headache attacks, there is a strong recommendation for oxygen (100%) with a flow of at least 12 L/min over 15 min and 6 mg subcutaneous sumatriptan. Prophylaxis of cluster headache attacks with verapamil at a daily dose of at least 240 mg (maximum dose depends on efficacy and tolerability) is recommended. Corticosteroids are efficacious in cluster headache. To reach an effect, the use of at least 100 mg prednisone (or equivalent corticosteroid) given orally or at up to 500 mg iv per day over 5 days is recommended. Lithium, topiramate, and galcanezumab (only for episodic cluster headache) are recommended as alternative treatments. Noninvasive vagus nerve stimulation is efficacious in episodic but not chronic cluster headache. Greater occipital nerve block is recommended, but electrical stimulation of the greater occipital nerve is not recommended due to the side effect profile.

Current treatment options for cluster headache: limitations and the unmet need for better and specific treatments-a consensus article

AIM

Treatment for cluster headache is currently based on a trial-and-error approach. The available preventive treatment is unspecific and based on few and small studies not adhering to modern standards. Therefore, the authors collaborated to discuss acute and preventive treatment in cluster headache, addressing the unmet need of safe and tolerable preventive medication from the perspectives of people with cluster headache and society, headache specialist and cardiologist.

FINDINGS

The impact of cluster headache on personal life is substantial. Mean annual direct and indirect costs of cluster headache are more than 11,000 Euros per patient. For acute treatment, the main problems are treatment response, availability, costs and, for triptans, contraindications and the maximum use allowed. Intermediate treatment with steroids and greater occipital nerve blocks are effective but cannot be used continuously. Preventive treatment is sparsely studied and overall limited by relatively low efficacy and side effects. Neurostimulation is a relevant option for treatment-refractory chronic patients. From a cardiologist's perspective use of verapamil and triptans may be worrisome and regular follow-up is essential when using verapamil and lithium.

CONCLUSION

We find that there is a great and unmet need to pursue novel and targeted preventive modalities to suppress the horrific pain attacks for people with cluster headache.

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.

Obstetric and Gynecologic Disorders and the Nervous System

OBJECTIVE

This article discusses obstetric and gynecologic associations with common neurologic disorders.

LATEST DEVELOPMENTS

Neurologic complications of obstetric and gynecologic disorders can arise throughout the lifespan. Caution should be exercised when prescribing fingolimod and natalizumab to patients with multiple sclerosis who are of childbearing potential because of the risk of disease rebound when they are discontinued. OnabotulinumtoxinA is considered safe in pregnancy and lactation based on long-term observational data. Hypertensive disorders of pregnancy are associated with higher subsequent cerebrovascular risk, likely via multiple mechanisms.

ESSENTIAL POINTS

Neurologic disorders may present in a variety of obstetric and gynecologic contexts, with meaningful implications for recognition and treatment. These interactions must be considered when treating women with neurologic conditions.

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.

Management of Trigeminal Autonomic Cephalalgias Including Chronic Cluster: A Review

Importance

Trigeminal autonomic cephalalgias (TACs) comprise a unique collection of primary headache disorders characterized by moderate or severe unilateral pain, localized in in the area of distribution of the first branch of the trigeminal nerve, accompanied by cranial autonomic symptoms and signs. Most TACs are rare diseases, which hampers the possibility of performing randomized clinical trials and large studies. Therefore, knowledge of treatment efficacy must be based only on observational studies, rare disease registries, and case reports, where real-world data and evidence play an important role in health care decisions.

Observations

Chronic cluster headache is the most common of these disorders, and the literature offers some evidence from randomized clinical trials to support the use of pharmacologic and neurostimulation treatments. Galcanezumab, a monoclonal antibody targeting the calcitonin gene-related peptide, was not effective at 3 months in a randomized clinical trial but showed efficacy at 12 months in a large case series. For the other TACs (ie, paroxysmal hemicrania, hemicrania continua, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing, and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms), only case reports and case series are available to guide physicians in everyday management.

Conclusions and Relevance

The accumulation of epidemiologic, pathophysiologic, natural history knowledge, and data from case series and small controlled trials, especially over the past 20 years from investigators around the world, has added to the previously limited evidence and has helped advance and inform the treatment approach to rare TACs, which can be extremely challenging for clinicians.

Preventive treatment of refractory chronic cluster headache: systematic review and meta-analysis

BACKGROUND

Preventive treatment for refractory chronic cluster headache (rCCH) is challenging and many therapies have been tried.

OBJECTIVE

To study what could be considered the therapy of choice in rCCH through a systematic review and meta-analysis.

METHODS

This review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol was registered in PROSPERO (ID CRD42021290983). A systematic search was performed in MEDLINE, Embase, Cochrane, clinicaltrials.gov, and the WHO's-International-Clinical-Trials-Registry-Platform. Studies on the preventive treatment for rCCH as defined by the European Headache Federation consensus statement were included. A meta-analysis of the pooled response rate was conducted for the different therapies.

RESULTS

Of 336 results, 45 were eligible for inclusion. Most articles studied the effect of neuromodulation as a preventive treatment for rCCH. The most studied neuromodulation technique was occipital nerve stimulation (ONS), with a pooled response rate in the meta-analysis of 57.3% (95% CI 0.481-0.665). Deep brain stimulation (DBS) was the second most studied treatment with a pooled response rate of 77.0% (95% CI 0.594-0.957). DBS results were more heterogeneous than ONS, which could be related to the different stimulation targets in DBS studies, and reported more serious adverse events than in ONS studies. The remaining therapies (anti-CGRP pathway drugs, warfarin, ketamine-magnesium infusions, serial occipital nerve blocks, clomiphene, onabotulinum toxin A, ketogenic diet, sphenopalatine ganglion radiofrequency or stimulation, vagus nerve stimulation, percutaneous bioelectric current stimulation, upper cervical cord stimulation, and vidian neurectomy) present weaker results or have less quality of evidence.

CONCLUSIONS

The results of this systematic review and meta-analysis suggest that ONS could be the first therapeutic strategy for patients with rCCH based on the current evidence.

Transnasal endoscopy-guided percutaneous access to the sphenopalatine ganglion for neurostimulation in the treatment of primary headache: operative technique and feasibility

OBJECTIVES

Cluster headache is considered a trigeminal autonomic cephalalgia and may present with characteristic symptoms of sympathetic/parasympathetic activation on the affected side of the face, such as nasal discharge, tearing, and conjunctival injection. Invasive therapies targeting the sphenopalatine ganglion have been performed in these headache syndromes and can have a medication-sparing effect, especially in refractory, difficult-to-manage cases. The gate control theory of pain suggests that electric pulses delivered to nerve tissues can modulate neuronal activity, thus aiding in management of nociceptive or neuropathic pain, and studies have demonstrated the efficacy and safety of sphenopalatine ganglion neurostimulation. Within this context, we sought to assess the feasibility of a new surgical technique for neurostimulation of the sphenopalatine ganglion in a cadaver dissection model.

METHODS

The technique was developed through dissection of two cadaver heads. We divided the procedure into two stages: an endonasal endoscopic approach to expose the sphenopalatine ganglion and confirm electrode placement, and a cervicofacial approach to introduce the electrode array and position the internal pulse-generator unit. Computed tomography was performed to confirm implant placement at the end of the procedure.

RESULTS

The pulse-generator unit was successfully placed through a retroauricular incision, as is already standard for cochlear implant placement. This should reduce the incidence of perioperative sequelae, especially pain and swelling in the oral region, which are a common complication of previous approaches used for this purpose. Control imaging confirmed proper electrode placement. The device used in this study allows the patient to modulate the intensity of the stimulus, reducing or even obviating the need for drug therapy.

CONCLUSION

The novel technique described herein, based on percutaneous access guided by transmaxillary endoscopy, can provide great precision in electrode array positioning and decreased perioperative morbidity, combining the advantages of endoscopic approaches with those of the retroauricular route.

LEVEL OF EVIDENCE: 3

Effect of acupuncture at the sphenopalatine ganglion for the treatment of moderate to severe seasonal allergic rhinitis: Study protocol for a three-armed randomized controlled trial

Introduction

Seasonal allergic rhinitis (SAR) is a major health problem with a relatively high worldwide prevalence that severely limits the quality of life for sufferers. Acupuncture is widely used for SAR treatment in China; however, the evidence on the efficacy of acupuncture at the sphenopalatine ganglion (SPG) for SAR is inconclusive. Therefore, this study aims to investigate the efficacy and safety of acupuncture at the SPG acupoint for the treatment of SAR.

Methods and analysis

A total of 120 participants with SAR will be recruited and randomly assigned to the acupuncture group, placebo acupuncture (PA) group, or rescue medication (RM) group with a 1:1:1 allocation ratio. Participants in the acupuncture group and PA group will receive 8 sessions of acupuncture stimulus at the SPG plus RM or 8 sessions of shallow needling at the SPG acupoint plus RM for 4 weeks with a 4-week follow-up in the first year and a 1-week follow-up in the second year. Participants in the RM group will only receive RM throughout the study. The primary outcome is the change from baseline in the average daily combined symptoms and medication score (CSMS) over weeks 1–4. All analysis will be based on an intention-to-treat principle. All statistical tests will be two-sided and a p-value < 0.05 will be considered to be statistically significant.

Guidelines of the International Headache Society for Controlled Clinical Trials in Cluster Headache

In 1995, a committee of the International Headache Society developed and published the first edition of the Guidelines for Controlled Trials of Drugs in Cluster Headache. These have not been revised. With the emergence of new medications, neuromodulation devices and trial designs, an updated version of the International Headache Society Guidelines for Controlled Clinical Trials in Cluster Headache is warranted. Given the scarcity of evidence-based data for cluster headache therapies, the update is largely consensus-based, but takes into account lessons learned from recent trials and demands by patients. It is intended to apply to both drug and neuromodulation treatments, with specific proposals for the latter when needed. The primary objective is to propose a template for designing high quality, state-of-the-art, controlled clinical trials of acute and preventive treatments in episodic and chronic cluster headache. The recommendations should not be regarded as dogma and alternative solutions to particular methodological problems should be explored in the future and scientifically validated.

Patient-identified burden and unmet needs in patients with cluster headache: An evidence-based qualitative literature review

Objectives:

To qualitatively identify evidence-based literature related to the daily burden and unmet treatment and psychosocial needs of patients with cluster headache (CH).

Methods:

A literature search was conducted through October 20, 2020 across MEDLINE, EMBASE, CINAHL, and PsychInfo databases exploring quality of life (QoL) and disease burden in adults with CH. The search was restricted to full-text reports in peer-reviewed journals. Methodologic quality was assessed using the Critical Skills Appraisal Program.

Results:

From 11 identified publications, QoL was reduced in persons living with CH, with significant psychological, social, and socio-economic burdens, and work-related disability. The CH disease trajectory is complex, with patients experiencing the impact of their disease across multiple domains beyond the biological manifestation of the disease including stigma, employment limitations, and suicidal ideation, and with a lack of effective treatment from the patient perspective.

Discussion:

These findings strengthen comprehension of the CH patient experience, enabling a deeper understanding of the patients’ perspective and experience of their disease andunmet needs, providing a basis for future research into this debilitating condition. Minor limitations of this study include data extraction and study selection biases.

Recent advances in the diagnosis and management of cluster headache

Cluster headache, a primary headache disorder, consists of short (15-180 minutes), frequent (up to eight a day), unilateral attacks of facial pain with associated ipsilateral autonomic features and restlessness. The attacks are suspected to be one of the most painful human experiences, and the disorder is associated with a high rate of suicidal ideation. Proper diagnosis is key, as some of the most effective treatments, such as high flow oxygen gas, are rarely used in other headache disorders. Yet diagnostic delay is typically years for this disorder, as it is often confused with migraine and trigeminal neuralgia, and secondary causes may be overlooked. This review covers the clinical, pathophysiologic, and therapeutic features of cluster headache. Recent updates in diagnosis include the redefinition of chronic cluster headache (remission periods lasting less than three months instead of the previous one month), and recent advances in management include new treatments for episodic cluster headache (galcanezumab and non-invasive vagus nerve stimulation).

Effects of acute and preventive therapies for episodic and chronic cluster headache: A scoping review of the literature

BACKGROUND

Cluster headache is the most common primary headache disorder of the trigeminal autonomic cephalalgias, and it is highly disabling.

OBJECTIVE

We undertake a scoping review to characterize therapies to prevent and acutely treat cluster headache, characterize trial methodology utilized in studies, and recommend future trial "good practices." We also assess homogeneity of studies and feasibility for future network meta-analyses (NMAs) to compare acute and preventive treatments for cluster headache.

METHODS

A priori protocol for this scoping review was registered and available on Open Science Forum. We sought studies that enrolled adult patients with cluster headache as identified by accepted diagnostic criteria. Both randomized controlled trials (RCTs) and observational studies (with a control group) were included. The interventions of interest were medications, procedures, devices, surgeries, and behavioral/psychological interventions, whereas comparators of interest were placebo, sham, or other active treatments. Outcomes were predefined; however, we did not exclude studies lacking these outcomes. A systemic search was conducted in Ovid Medline, Embase, and Cochrane. We performed a targeted search for conference abstracts from journals prominent in the field.

RESULTS

We identified 56 studies: 45 RCTs, four studies only available in clinical trial registries, and seven observational studies. Of the 45 RCTs, 20 focused on acute therapies and 25 on preventive therapies. Overall, we determined that it is feasible to pursue a NMA for acute therapy focusing on 15 or 30-min headache reduction for acute trials, as we identified 11 trials in the combined population of patients with either episodic or chronic cluster headache (2 trials in populations with chronic cluster headache were also found). For preventive therapy of cluster headache, we identified trials with common outcomes that may be considered for NMA, however, as these trials had differences in treatment effect modifiers that could not be corrected, NMAs appear infeasible for this indication. We identified new studies looking at noninvasive vagal nerve stimulation, sphenopalatine ganglion stimulation, prednisone, and oxygen published since the most recent systematic review in the field, although these acute treatments were previously identified as effective. However, for calcitonin gene-related peptide (CGRP) monoclonal antibodies, galcanezumab demonstrated effectiveness in episodic cluster headache, but a lack of effectiveness in chronic cluster headache, and fremanezumab was not effective for episodic nor chronic cluster headache. This finding highlights that CGRP monoclonal antibodies may not show a class effect in cluster headache prevention and need to be considered individually.

CONCLUSIONS

We describe the treatment landscape of cluster headache for both acute and preventive treatments. Last, we present the NMAs we will undertake in acute therapies of cluster headache.

Osteopathic Manipulation of the Sphenopalatine Ganglia Versus Sham Manipulation, in Obstructive Sleep Apnoea Syndrom: A Randomised Controlled Trial

(1) Background: osteopathic manipulation of the sphenopalatine ganglia (SPG) blocks the action of postganglionic sensory fibres. This neuromodulation can reduce nasal obstruction and enhance upper airway stability. We investigated the manipulation of the SPG in 31 patients with obstructive sleep apnoea syndrome (OSAS); (2) Methods: Randomised, controlled, double-blind, crossover study. Participants received active (AM), then sham manipulation (SM), or vice versa. The primary endpoint was apnoea-hypopnoea index (AHI). Secondary endpoints were variation of nasal obstruction evaluated by peak nasal inspiratory flow (PNIF) and upper airways stability evaluated by awake critical closing pressure [awake Pcrit]), at 30 min and 24 h. Schirmer’s test and pain were assessed immediately post-manipulation. Tactile/gustatory/olfactory/auditory/nociceptive/visual sensations were recorded. Adverse events were collected throughout. (3) Results: SPG manipulation did not reduce AHI (p = 0.670). PNIF increased post-AM but not post-SM at 30 min (AM-SM: 18 [10; 38] L/min, p = 0.0001) and 24 h (23 [10; 30] L/min, p = 0.001). There was no significant difference on awake Pcrit (AM-SM) at 30 min or 24 h). Sensations were more commonly reported post-AM (100% of patients) than post-SM (37%). Few adverse events and no serious adverse events were reported. (4) Conclusions: SPG manipulation is not supported as a treatment for OSAS but reduced nasal obstruction. This effect remains to be confirmed in a larger sample before using this approach to reduce nasal congestion in CPAP-treated patients or in mild OSAS.

Neurostimulation Treatment in Chronic Cluster Headache-a Narrative Review

PURPOSE OF REVIEW

In this narrative review, the current literature on neurostimulation methods in the treatment of chronic cluster headache is evaluated. These neurostimulation methods include deep brain stimulation, vagus nerve stimulation, greater occipital nerve stimulation, sphenopalatine ganglion stimulation, transcranial magnetic stimulation, transcranial direct current stimulation, supraorbital nerve stimulation, and cervical spinal cord stimulation.

RECENT FINDINGS

Altogether, only nVNS and SPG stimulation are supported by at least one positive sham-controlled clinical trial for preventive and acute attack (only SPG stimulation) treatment. Other clinical trials either did not control at all or controlled by differences in the stimulation technique itself but not by a sham-control. Case series report higher responder rates. The evidence for these neurostimulation methods in the treatment of chronic cluster headache is poor and in part contradictive. However, except deep brain stimulation, tolerability and safety of these methods are good so that in refractory situations application might be justified in individual cases.

Safety and efficacy of occipital nerve stimulation for attack prevention in medically intractable chronic cluster headache (ICON): a randomised, double-blind, multicentre, phase 3, electrical dose-controlled trial

BACKGROUND

Occipital nerve stimulation (ONS) has shown promising results in small uncontrolled trials in patients with medically intractable chronic cluster headache (MICCH). We aimed to establish whether ONS could serve as an effective treatment for patients with MICCH.

METHODS

The ONS in MICCH (ICON) study is an investigator-initiated, international, multicentre, randomised, double-blind, phase 3, electrical dose-controlled clinical trial. The study took place at four hospitals in the Netherlands, one hospital in Belgium, one in Germany, and one in Hungary. After 12 weeks' baseline observation, patients with MICCH, at least four attacks per week, and history of being non-responsive to at least three standard preventive drugs, were randomly allocated (at a 1:1 ratio using a computer-generated permuted block) to 24 weeks of occipital nerve stimulation at either 100% or 30% of the individually determined range between paraesthesia threshold and near-discomfort (double-blind study phase). Because ONS causes paraesthesia, preventing masked comparison versus placebo, we compared high-intensity versus low-intensity ONS, which are hypothesised to cause similar paraesthesia, but with different efficacy. In weeks 25-48, participants received individually optimised open-label ONS. The primary outcome was the weekly mean attack frequency in weeks 21-24 compared with baseline across all patients and, if a decrease was shown, to show a group-wise difference. The trial is closed to recruitment (ClinicalTrials.gov NCT01151631).

FINDINGS

Patients were enrolled between Oct 12, 2010, and Dec 3, 2017. We enrolled 150 patients and randomly assigned 131 (87%) to treatment; 65 (50%) patients to 100% ONS and 66 (50%) to 30% ONS. One of the 66 patients assigned to 30% ONS was not implanted and was therefore excluded from the intention-to-treat analysis. Because the weekly mean attack frequencies at baseline were skewed (median 15·75; IQR 9·44 to 24·75) we used log transformation to analyse the data and medians to present the results. Median weekly mean attack frequencies in the total population decreased from baseline to 7·38 (2·50 to 18·50; p<0·0001) in weeks 21-24, a median change of -5·21 (-11·18 to -0·19; p<0·0001) attacks per week. In the 100% ONS stimulation group, mean attack frequency decreased from 17·58 (9·83 to 29·33) at baseline to 9·50 (3·00 to 21·25) at 21-24 weeks (median change from baseline -4·08, -11·92 to -0·25), and for the 30% ONS stimulation group, mean attack frequency decreased from 15·00 (9·25 to 22·33) to 6·75 (1·50 to 16·50; -6·50, -10·83 to -0·08). The difference in median weekly mean attack frequency between groups at the end of the masked phase in weeks 21-24 was -2·42 (95% CI -5·17 to 3·33). In the masked study phase, 129 adverse events occurred with 100% ONS and 95 occurred with 30% ONS. None of the adverse events was unexpected but 17 with 100% ONS and eight with 30% ONS were labelled as serious, given they required brief hospital admission for minor hardware-related issues. The most common adverse events were local pain, impaired wound healing, neck stiffness, and hardware damage.

INTERPRETATION

In patients with MICCH, both 100% ONS intensity and 30% ONS intensity substantially reduced attack frequency and were safe and well tolerated. Future research should focus on optimising stimulation protocols and disentangling the underlying mechanism of action.

FUNDING

The Netherlands Organisation for Scientific Research, the Dutch Ministry of Health, the NutsOhra Foundation from the Dutch Health Insurance Companies, and Medtronic.

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.

Cluster Headache and Other Trigeminal Autonomic Cephalalgias

PURPOSE OF REVIEW

The trigeminal autonomic cephalalgias (TACs) are relatively rare, but they represent a distinct set of syndromes that are important to recognize. Despite their unique features, TACs often go undiagnosed or misdiagnosed for several years, leading to unnecessary pain and suffering. A significant proportion of TAC presentations may have secondary causes.

RECENT FINDINGS

The underlying pathophysiology of TACs is likely rooted in hypothalamic dysfunction and derangements in the interplay of circuitry involving trigeminovascular, trigeminocervical, trigeminoautonomic, circadian, and nociceptive systems. Recent therapeutic advancements include a better understanding of how to use older therapies more effectively and the identification of new approaches.

SUMMARY

TAC syndromes are rare but important to recognize because of their debilitating nature and greater likelihood for having potentially serious underlying causes. Although treatment options have remained somewhat limited, scientific inquiry is continually advancing our understanding of these syndromes and how best to manage them.

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 pathophysiology - insights from current and emerging treatments

Cluster headache is a debilitating primary headache disorder that affects approximately 0.1% of the population worldwide. Cluster headache attacks involve severe unilateral pain in the trigeminal distribution together with ipsilateral cranial autonomic features and a sense of agitation. Acute treatments are available and are effective in just over half of the patients. Until recently, preventive medications were borrowed from non-headache indications, so management of cluster headache is challenging. However, as our understanding of cluster headache pathophysiology has evolved on the basis of key bench and neuroimaging studies, crucial neuropeptides and brain structures have been identified as emerging treatment targets. In this Review, we provide an overview of what is known about the pathophysiology of cluster headache and discuss the existing treatment options and their mechanisms of action. Existing acute treatments include triptans and high-flow oxygen, interim treatment options include corticosteroids in oral form or for greater occipital nerve block, and preventive treatments include verapamil, lithium, melatonin and topiramate. We also consider emerging treatment options, including calcitonin gene-related peptide antibodies, non-invasive vagus nerve stimulation, sphenopalatine ganglion stimulation and somatostatin receptor agonists, discuss how evidence from trials of these emerging treatments provides insights into the pathophysiology of cluster headache and highlight areas for future research.

Recently available and emerging therapeutic strategies for the acute and prophylactic management of cluster headache: a systematic review and expert opinion

Introduction: Although it causes a huge burden to sufferers, cluster headache (CH), remains an undertreated condition, partly due to the absence of established acute and prophylactic treatment options. New therapeutic approaches providing fast and safe relief from CH are needed. Areas covered: A systematic review was conducted, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendation on recently published (last 5 years) papers on CH treatment. The authors also collected preliminary results from ongoing trials on emerging therapeutic/preventive pharmacological and interventional approaches for CH. Studies and results are reviewed and discussed. Expert opinion: The complexity of CH pathophysiology prevents the definition of reliable acute and preventive treatments. In the real-world clinical setting, several treatments are combined to provide relief to patients and increase their quality of life. Drugs targeting neuropeptides or their receptors within the trigeminovascular network are of particular interest to prevent CH attacks. Calcitonin gene-related peptide (CGRP) blockade seems attractive and promising, but studies on anti-CGRP monoclonal antibodies indicated rather modest or even absence of a prophylactic effect. A deeper insight into CH pathophysiology, and combined approaches may lead the path to new, more effective, and personalized CH therapies.

Trigeminocardiac Reflex Induced by Maxillary Nerve Stimulation during Sphenopalatine Ganglion Implantation: A Case Series

BACKGROUND

The trigeminocardiac reflex (TCR) is a brainstem reflex following stimulation of the trigeminal nerve, resulting in bradycardia, asystole and hypotension. It has been described in maxillofacial and craniofacial surgeries. This case series highlights TCR events occurring during sphenopalatine ganglion (SPJ) neurostimulator implantation as part of the Pathway CH-2 clinical trial "Sphenopalatine ganglion Stimulation for Treatment of Chronic Cluster Headache".

METHODS

This is a case series discussing sphenopalatine ganglion neurostimulator implantation in the pterygopalatine fossa as treatment for intractable cluster headaches. Eight cases are discussed with three demonstrating TCR events. All cases received remifentanil and desflurane for anesthetic maintenance.

RESULTS

Each patient with a TCR event experienced severe bradycardia. In two cases, TCR resolved with removal of the introducer, while the third case's TCR event resolved with both anticholinergic treatment and surgical stimulation cessation.

CONCLUSION

Each TCR event occurred before stimulation of the fixed introducer device, suggesting the cause for the TCR events was mechanical in origin. Due to heightened concern for further TCR events, all subsequent cases had pre-anesthesia external pacing pads placed. Resolution can occur with cessation of surgical manipulation and/or anticholinergic treatment. Management of TCR events requires communication between surgical teams and anesthesia providers, especially during sphenopalatine ganglion implantation when maxillary nerve stimulation is possible.

Recent Advances in the Management of Cluster Headache

Purpose of review

Among the spectrum of pain conditions, cluster headache represents one of the most severe. Targeted therapies for cluster headache are evolving thus improving the available therapeutic armamentarium. A better understanding of the currently available therapies, as well as new and emerging options, may aide physicians to manage affected sufferers better by evolving treatment guidance.

Recent findings

While classic first-line medications are useful in some patients with cluster headache, they are often accompanied by significant side effects that limit their use. Recently, novel treatments with better tolerability and decreased medication interactions have proven to be effective. A remarkable example of this is the blockage of the calcitonin gene-related peptide pathway with monoclonal antibodies, which may be a key element in the future treatment of cluster headache. The sphenopalatine ganglion and vagus nerve perform a critical role in the regulation of pain and the trigeminal autonomic reflex. Neuromodulation therapies targeting these structures have shown excellent tolerability and few significant adverse events, constituting a promising form of treatment. Finally, several potential therapeutic targets are examined in this review, such as small molecule CGRP receptor antagonists, known as gepants, and serotonin receptor 5-HT1F receptor agonists: ditans.

Summary

In summary, a deepening of the understanding of cluster headache mechanisms in recent years has driven the evolution of sophisticated therapeutic approaches that could allow a new era in the treatment of this difficult condition.

Ketamine-Magnesium for Refractory Chronic Cluster Headache: A Case Series

OBJECTIVES

To evaluate the safety and efficacy of ketamine-magnesium combination to reduce attacks in a series of patients with refractory chronic cluster headache (rCCH).

BACKGROUND

Refractory chronic cluster headache (CCH) is a rare but highly debilitating condition that needs new treatment options. A previous publication reported that a single infusion of ketamine-magnesium combination was effective in 2 patients with rCCH.

METHODS

The treatment was proposed to consecutive patients with rCCH seen in 2 French hospitals between November 2015 and February 2020 and who were resistant to at least 3 preventive treatments. They received a single ketamine infusion (0.5 mg/kg over 2 hours) combined with magnesium sulfate (3000 mg). The main outcome was a comparison of the number of daily attacks 2 weeks prior to the ketamine-magnesium infusion and 1 week after (on days 7 and 8). The second outcome was the percentage of responders (patients with ≥50% reduction in the frequency of daily attacks). Safety was assessed by the recording of adverse events during infusion. Descriptive statistics are presented as mean ± standard deviation.

RESULTS

Seventeen patients (14 men), with an age of 35.2 ± 8.1 years, were included. They presented with CCH for 6.6 ± 4.3 years. The number of daily attacks decreased from 4.3 ± 2.4 before treatment to 1.3 ± 1.0 after treatment (difference: -3.1 (95% CI: -4.5 to -1.6), P < .001). Seventy six percent (13/17) were responders. Transient and mild sedation was reported by 7/17 patients (41.2%).

CONCLUSIONS

The ketamine-magnesium combination seems an effective and well-tolerated therapy for rCCH. Placebo-controlled studies should be conducted to further confirm these findings.

Primaries non-migraine headaches treatment: a review

In the "headache world," great attention has always been paid to migraine patients, especially for the research and development of new therapies. For the other forms of primary headaches, especially those of Chapters 2 and 3 of the classification, there are however therapies that, even if not specific, can give significant results. Tension-type headache recognizes in NSAIDs the most effective drugs to treat acute attack, while prevention is based on the use of tricyclic antidepressants and muscle relaxants. For TACs, the discussion is more complex: first of all, there are two forms of primary headache that respond absolutely to indomethacin. For these, the main problem is how to manage the possible side effects arising from prolonged treatments and possibly what to use as an alternative. For cluster headaches and short-lasting unilateral neuralgiform headache attacks, we have drugs with good efficacy as regards medical therapy, such as verapamil or lamotrigine, but in recent years, neuromodulation techniques, both surgical and non-invasive, have also been affirming themselves, which represent a more possibility for forms of headache that are often very disabling and resistant to common analgesics.

Reducing Episodic Cluster Headaches: Focus on Galcanezumab

The involvement of calcitonin gene-related peptide in migraine and cluster headache has led to the recent development of new therapies. Galcanezumab, a novel monoclonal antibody targeting the calcitonin gene-related peptide, is approved for the migraine prevention and has recently been tested for the prevention of cluster headache. Two clinical trials have been conducted to investigate the efficacy and safety of galcanezumab in episodic cluster headache and chronic cluster headache. While efficacy endpoints were not met in the chronic subtype, galcanezumab reduced the weekly frequency of attacks in patients with episodic cluster headaches. In both studies, the antibody was well tolerated. This review summarizes and critically reviews the available data regarding the rationale behind targeting the calcitonin gene-related peptide with galcanezumab for the prevention of cluster headache.

CGRP pathway monoclonal antibodies for cluster headache

INTRODUCTION

The involvement of the calcitonin gene-related peptide (CGRP) pathway in primary headache disorders, especially migraine, had led to recent success in the development of new migraine therapies. The CGRP pathway also plays a role in the pathophysiology of cluster headache, so CGRP pathway monoclonal antibodies have been studied in the prevention of cluster headache attacks.

AREAS COVERED

This review will outline the trials of fremanezumab and galcanezumab, the two CGRP pathway monoclonal antibodies that have undergone trials in cluster headache prevention. This review will highlight key efficacy and safety outcomes from the trials.

EXPERT OPINION

Galcanezumab was shown to be efficacious, reducing the frequency of attacks in episodic cluster headache, while fremanezumab failed its primary endpoint in episodic cluster headache. Both fremanezumab and galcanezumab trials in chronic cluster headache were terminated after futility analysis predicting the failure of both trials to fulfil their primary endpoint. The role of CGRP in cluster headache supports ongoing trials of the remaining CGRP pathway monoclonal antibodies and gepants for preventive and acute treatment. A broad view would include targeting neuropeptides involved in parasympathetic signaling in cluster headache, such as pituitary adenylate cyclase-activating peptide (PACAP); such targets warrant exploration in the search of new treatments.