Comparative Impact of Pharmacological Therapies on Cluster Headache Management: A Systematic Review and Network Meta-Analysis

It is important to find effective and safe pharmacological options for managing cluster headache (CH) because there is limited evidence from studies supporting the general efficacy and safety of pharmacological therapies. This systematic review and network meta-analysis (NMA) analyzed published randomized controlled trials (RCTs) to evaluate the efficacy and safety of pharmacological treatments in patients with CH. The PubMed and Embase databases were searched to identify RCTs that evaluated the efficacy and safety of pharmacological treatments for CH. Efficacy outcomes included frequency and duration of attacks, pain-free rate, and the use of rescue agents. Safety outcomes were evaluated based on the number of patients who experienced adverse events. A total of 23 studies were included in the analysis. The frequency of attacks was reduced (mean difference (MD) = −1.05, 95% confidence interval (CI) = −1.62 to −0.47; p = 0.0004), and the pain-free rate was increased (odds ratio (OR) = 3.89, 95% CI = 2.76−5.48; p < 0.00001) in the pharmacological treatment group, with a lower frequency of rescue agent use than the placebo group. Preventive, acute, and triptan or non-triptan therapies did not show significant differences in efficacy (p > 0.05). In the NMA, different results were shown among the interventions; for example, zolmitriptan 5 mg was more effective than zolmitriptan 10 mg in the pain-free outcome (OR = 0.40, 95% CI = 0.19−0.82; p < 0.05). Pharmacological treatment was shown to be more effective than placebo to manage CH with differences among types of therapies and individual interventions, and it was consistently shown to be associated with the development of adverse events. Thus, individualized therapy approaches should be applied to treat CH in real-world practice.

Headache as a Presenting Symptom of Deep Brain Stimulator Generator Failure

While a headache can have a wide variety of clinical presentations, it may occasionally be a red flag for underlying pathology that should prompt further investigation. Here, we present a case report demonstrating headache as an uncommon symptom of deep brain stimulation (DBS) device failure and discuss its clinical significance in the rapidly expanding list of current indications of DBS treatment. A 61-year-old female underwent bilateral hypothalamic DBS implantation for refractory morbid obesity. After a successful course involving significant weight loss, the patient began to experience worsening of her chronic headaches, refractory to her existing regiment. On interrogation, her generator was found to be depleted and its subsequent replacement led to a near total resolution of her headaches. This represents one of the few reported instances of headache as a sign of device failure in DBS treatment, thus adding to the wide possibility of headache presentations and their underlying pathology.

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.

Sphenopalatine Ganglion Stimulation Upregulates Transport of Temozolomide across the Blood-Brain Barrier

Sphenopalatine ganglion (SPG) stimulation has been shown to reversibly alter blood-brain barrier (BBB) permeability. It is widely used for the treatment of cluster headaches in Europe and is well tolerated in humans. The therapeutic potential for SPG stimulation in other central nervous system (CNS) diseases has yet to be explored. Glioblastoma Multiforme (GBM) remains one of the most difficult primary CNS neoplasms to treat, with an average survival of approximately 18 months at the time of diagnosis. Since 2004, the gold standard of treatment for GBM in the United States includes surgery followed by treatment with temozolomide (TMZ) and radiation. We sought to determine if SPG stimulation could increase chemotherapy concentrations in rodent brains with an intact BBB. Here, we show a statistically significant (p = 0.0006), five-fold upregulation of TMZ crossing the BBB and reaching brain parenchyma in rats receiving low-frequency (LF, 10 Hz) SPG stimulation. All the measurements were performed using a highly sensitive liquid chromatography mass spectrometry (LCMS) method that was developed for quantitation of TMZ in plasma and brain tissue. Our treatment paradigm shows novel delivery route by which we could more effectively and safely deliver TMZ in a targeted manner, to minimize systemic toxicity and maximize action at the target tissue.

The fifth cranial nerve in headaches

The fifth cranial nerve is the common denominator for many headaches and facial pain pathologies currently known. Projecting from the trigeminal ganglion, in a bipolar manner, it connects to the brainstem and supplies various parts of the head and face with sensory innervation. In this review, we describe the neuroanatomical structures and pathways implicated in the sensation of the trigeminal system. Furthermore, we present the current understanding of several primary headaches, painful neuropathies and their pharmacological treatments. We hope that this overview can elucidate the complex field of headache pathologies, and their link to the trigeminal nerve, to a broader field of young scientists.

Sphenopalatine ganglion stimulation is a reversible and frequency-dependent modulator of the blood-brain barrier

BACKGROUND

The sphenopalatine ganglion (SPG) is a vasoactive mediator of the anterior intracranial circulation in mammals. SPG stimulation has been demonstrated to alter blood-brain barrier (BBB) permeability, although this phenomenon is not well characterized.

OBJECTIVE

To determine the effect of SPG stimulation on the BBB using rat models.

METHODS

Extravasation of fluorescent tracer 70 kDa FITC-dextran into rat brain specimens was measured across a range of stimulation parameters to assess BBB permeability. Tight junction (TJ) morphology was compared by assessing differences in the staining of proteins occludin and ZO-1 and analyzing ultrastructural changes on transmission electron microscopy (TEM) between stimulated and unstimulated specimens.

RESULTS

SPG stimulation at 10 Hz maximally increased BBB permeability, exhibiting a 6-fold increase in fluorescent traceruptake (1.66% vs 0.28%, p < 0.0001). This effect was reversed 4-hours after stimulation (0.36% uptake, p = 0.99). High-frequency stimulation at 20 Hz and 200 Hz did not increase tracer extravasation, (0.26% and 0.28% uptake, p = >0.999 and p = 0.998, respectively). Stimulation was associated a significant decrease in the colocalization of occludin and ZO-1 with endothelial markers in stimulated brains compared to control (74.6% vs. 39.7% and 67.2% vs. 60.4% colocalization, respectively, p < 0.0001), and ultrastructural changes in TJ morphology associated with increased BBB permeability were observed on TEM.

CONCLUSION

This study is the first to show a reversible, frequency-dependent increase in BBB permeability with SPG stimulation and introduces a putative mechanism of action through TJ disruption. Bypassing the BBB with SPG stimulation could enable new paradigms in delivering therapeutics to the CNS. Further study of this technology is needed.

Endogenous Neurostimulation and Physiotherapy in Cluster Headache: A Clinical Case

OBJECTIVE

The aim of this paper is to describe the progressive changes of chronic cluster headaches (CHs) in a patient who is being treated by a multimodal approach, using pharmacology, neurostimulation and physiotherapy.

SUBJECT

A male patient, 42 years of age was diagnosed with left-sided refractory chronic CH by a neurologist in November 2009. In June 2014, the patient underwent a surgical intervention in which a bilateral occipital nerve neurostimulator was implanted as a treatment for headache.

METHODS

Case report.

RESULTS

Primary findings included a decreased frequency of CH which lasted up to 2 months and sometimes even without pain. Besides this, there were decreased levels of anxiety, helplessness (PCS subscale) and a decreased impact of headache (HIT-6 scale). Bilateral pressure pain thresholds (PPTs) were improved along with an increase in strength and motor control of the neck muscles. These improvements were present at the conclusion of the treatment and maintained up to 4 months after the treatment.

CONCLUSIONS

A multimodal approach, including pharmacology, neurostimulation and physiotherapy may be beneficial for patients with chronic CHs. Further studies such as case series and clinical trials are needed to confirm these results.

Efficacy of Sphenopalatine Ganglion Radiofrequency in Refractory Chronic Cluster Headache

BACKGROUND

In the literature, there are only short series of radiofrequency of the sphenopalatine ganglion (SPG) to treat chronic refractory cluster headache (CCHr) with variable results. Furthermore, there is no consensus on which methodology to use: radiofrequency ablation (RFA) or pulsed radiofrequency (PRF).

METHODS

We conducted a prospective analysis of 37 patients with CCHr who underwent RFA or PRF of the SPG in our center between 2004 and 2015.

RESULTS

The mean age of the patients was 40 years (range, 26-59 years). PRF was performed in 24 patients, and RFA was performed in 13 patients. A total of 5 patients (13.5%) experienced complete clinical relief of both pain and parasympathetic symptoms, 21 patients (56.8%) had partial and transient relief, and 11 patients (29.7%) did not improve. There was no evidence of significant superiority of one radiofrequency modality over the other (P = 0.48). There were no complications associated with the technique. The passage of time tended to decrease the efficacy of both techniques (P < 0.001). The mean follow-up was 68.1 months (range, 15-148 months). To our knowledge, this is the series with the largest number of patients and the longest follow-up period published in the literature.

CONCLUSIONS

Radiofrequency of the SPG is a safe, fast, and partially effective method for the treatment of CCHr. Given its low rate of complications and its low economic cost, we think it should be one of the first invasive treatment options, prior to techniques with greater morbidity and mortality, such as neuromodulation.

Sphenopalatine ganglion stimulation for cluster headache, results from a large, open-label European registry

Background

Cluster headache (CH) is a disabling primary headache disorder characterized by severe periorbital pain. A subset of patients does not respond to established pharmacological therapy. This study examines outcomes of a cohort of mainly chronic CH patients treated with sphenopalatine ganglion (SPG) stimulation.

Methods

Patients were followed in an open-label prospective study for 12 months. Ninety-seven CH patients (88 chronic, 9 episodic) underwent trans-oral insertion of a microstimulator targeting the SPG. Patients recorded stimulation effect prospectively for individual attacks. Frequency, use of preventive and acute medications, headache impact (HIT-6) and quality of life measures (SF-36v2) were monitored at clinic visits. Per protocol, frequency responders experienced ≥ 50% reduction in attack frequency and acute responders treated ≥ 50% of attacks. HIT-6 responders experienced an improvement ≥ 2.3 units and SF-36 responders ≥ 4 units vs. baseline.

Results

Eighty-five patients (78 chronic, 7 episodic) remained implanted and were evaluated for effectiveness at 12 months. In total, 68% of all patients were responders, 55% of chronic patients were frequency responders and 32% of all patients were acute responders. 67% of patients using acute treatments were able to reduce the use of these by 52% and 74% of chronic patients were able to stop, reduce or remain off all preventive medications. 59% of all patients were HIT-6 responders, 67% were SF-36 responders.

Conclusions

This open-label registry corroborates that SPG stimulation is an effective therapy for CH patients providing therapeutic benefits and improvements in use of medication as well as headache impact and quality of life.

Electronic supplementary material

The online version of this article (10.1186/s10194-017-0828-9) contains supplementary material, which is available to authorized users.

Long-term effectiveness of sphenopalatine ganglion stimulation for cluster headache

Objectives

The sphenopalatine ganglion (SPG) plays a pivotal role in cluster headache (CH) pathophysiology as the major efferent parasympathetic relay. We evaluated the long-term effectiveness of SPG stimulation in medically refractory, chronic CH patients.

Methods

Thirty-three patients were enrolled in an open-label follow-up study of the original Pathway CH-1 study, and participated through 24 months post-insertion of a microstimulator. Response to therapy was defined as acute effectiveness in ≥ 50% of attacks or a ≥ 50% reduction in attack frequency versus baseline.

Results

In total, 5956 attacks (180.5 ± 344.8, range 2–1581 per patient) were evaluated. At 24 months, 45% (n = 15) of patients were acute responders. Among acute responders, a total of 4340 attacks had been treated, and in 78% of these, effective therapy was achieved using only SPG stimulation (relief from moderate or greater pain or freedom from mild pain or greater). A frequency response was observed in 33% (n = 11) of patients with a mean reduction of attack frequency of 83% versus baseline. In total, 61% (20/33) of all patients were either acute or frequency responders or both. The majority maintained their therapeutic response through the 24-month evaluation.

Conclusions

In the population of disabled, medically refractory chronic CH patients treated in this study, SPG stimulation is an effective acute therapy in 45% of patients, offering sustained effectiveness over 24 months of observation. In addition, a maintained, clinically relevant reduction of attack frequency was observed in a third of patients. These long-term data provide support for the use of SPG stimulation for disabled patients and should be considered after medical treatments fail, are not tolerated or are inconvenient for the patients.

Diagnosis and Management of Childhood Headache

Headache is one of the most common chief complaints seen in the pediatrician's office. Oftentimes, identifying the etiology of headache and differentiating primary and secondary causes can present a diagnostic conundrum. Understanding the most common causes of primary and secondary headache is vital to making a correct diagnosis. Here we review the typical presentations of the most common primary headache disorders and the approach to evaluation of the pediatric patient presenting with headache. Diagnostic workup, including the key features to elicit on physical examination, when to order head imaging, and the use of other ancillary tests, is discussed. Current treatment modalities and their indications are reviewed. We will also describe some of the new, emerging therapies that may alter the way we manage headache in the pediatric population. Headache can, at times, be a frustrating symptom seen in the pediatrician's office, but here we hope to better elucidate the approach to evaluation, management, and treatment as well as provide some hope in regards to more effective upcoming therapies.

A Review of Cardiovascular Autonomic Control in Cluster Headache

OBJECTIVE

This review aims to evaluate existing literature concerning cardiovascular autonomic function and CH. Suggestions about future research are offered and known difficulties in investigating the autonomic nervous system in cluster headache are discussed.

BACKGROUND

Little is known of the pathophysiological mechanisms behind cluster headache. Cranial autonomic features are an inherent and diagnostic feature; however, a number of studies and clinical observations support the involvement of systemic autonomic control in its pathophysiology. Further, cluster headache attacks are apparently more easily triggered during periods of parasympathetic dominance. A better understanding of this interaction may provide insight into central autonomic regulation and its role in cluster headache.

METHODS

A PubMed search was performed in April 2015 using the search terms "cluster headache," "cardiovascular," "autonomic nervous system," and "cardiac." References of identified articles were also searched for relevant articles. Studies were included if they contained data on cardiovascular or autonomic responses to autonomic tests, induced or spontaneous attacks.

RESULTS

In total, 22 studies investigating cardiac autonomic control in cluster headache were identified. Three overall categories of investigations exist: (1) Those studying changes in heart rate, blood pressure, and electrocardiographic changes; (2) those employing various clinical autonomic tests; and finally (3) those using spectral and nonlinear analysis of heart rate variability. Although not completely congruent, overall, results suggest ictal hyperactivation of the parasympathetic branch and a sympathetic deficit. Subclinical autonomic dysregulation is also present in the pain-free state.

CONCLUSION

Cardiac autonomic control is subclinically affected in cluster headache. The changes could be attributed to the suggested central dysregulation present in this disorder.

[Cluster headache treatment]

Acute treatment: sumatriptan, oxygen inhalation. Prophylactic treatment: verapamil, lithium carbonate. Transitional treatment.

SURGICAL TREATMENT

deep brain stimulation, occipital nerve stimulation, stimulation of the sphenopalatin ganglion.

Mechanisms of deep brain stimulation

Deep brain stimulation (DBS) is widely used for the treatment of movement disorders including Parkinson's disease, essential tremor, and dystonia and, to a lesser extent, certain treatment-resistant neuropsychiatric disorders including obsessive-compulsive disorder. Rather than a single unifying mechanism, DBS likely acts via several, nonexclusive mechanisms including local and network-wide electrical and neurochemical effects of stimulation, modulation of oscillatory activity, synaptic plasticity, and, potentially, neuroprotection and neurogenesis. These different mechanisms vary in importance depending on the condition being treated and the target being stimulated. Here we review each of these in turn and illustrate how an understanding of these mechanisms is inspiring next-generation approaches to DBS.

Unsuccessful pulsed radiofrequency of the sphenopalatine ganglion in patients with chronic cluster headache and subsequent successful thermocoagulation

We present the results of pulsed and continuous radiofrequency (CRF) of the sphenopalatine ganglion in a case series of 3 patients with chronic cluster headache (CCH). Three patients were referred to our neurosurgical department because of CCH, which was refractory to pharmacological treatment. They underwent pulsed radiofrequency of the sphenopalatine ganglion (PRF-SPG), and the procedure was performed through an infrazygomatic approach. In the PRF procedures, we applied 2 cycles of PRF at 42°C and 45 V for 120 seconds, with a pulse frequency of 2 Hz and a pulse width of 20 ms. In those procedures where thermocoagulation was carried out, 2 CRF lesions at 80°C for 90 seconds each were performed. Following corticosteroid and local anesthetic (40 mg of methylprednisolone and 1 mL of 1% lidocaine) injection, 2 patients had no pain relief at all, whereas the third one experienced a partial response, which lasted only 1 month and his pain then returned to its baseline level. Thus, this outcome was assessed as a nonsustained partial response. Therefore, all of them underwent a CRF lesioning of the SPG, and after this procedure, they achieved complete pain relief until the end of the follow-up period. Furthermore, the associated autonomic manifestations disappeared. The 3 patients presented in this case series failed to achieve adequate pain relief after PRF-SPG. However, these same patients subsequently underwent a successful CRF of the SPG.

Treatment of hemicrania continua with radiofrequency ablation and long-term follow-up

OBJECTIVE

The objective of this research is to describe novel procedural treatments for hemicrania continua that allow patients to remain off indomethacin.

METHODS

Case reports are presented.

RESULTS

We describe four distinct patients with indomethacin-responsive hemicrania continua who were unable to discontinue the use of indomethacin without headache recurrence. No other medications were effective for their syndrome. Secondary causes of headache were ruled out in each case. Each patient underwent diagnostic blockade of either the atlanto-axial joint, C2 dorsal root ganglion or sphenopalantine ganglion depending on their clinical examination and presence of cranial autonomic symptoms. A positive response led to a radiofrequency ablation of the C2 ventral ramus, C2 dorsal root ganglion or sphenopalantine ganglion, which provided headache relief in all case patients as complete as indomethacin. Long-term follow-up of these patients has shown that all have remained essentially headache free without the need for indomethacin. One patient has needed repeat radiofrequency procedures with consistent response.

CONCLUSION

Hemicrania continua is defined by its sensitivity to indomethacin but very few patients are able to discontinue the medication without headache recurrence. As the risks of chronic indomethacin use are substantial, alternative treatments are necessary to protect patient health. We are now able to suggest several radiofrequency ablation procedures as effective as indomethacin with long-term follow-up.

Treatment of Chronic Facial Pain Including Cluster Headache by Repetitive Transcranial Magnetic Stimulation of the Motor Cortex With Maintenance Sessions: A Naturalistic Study

OBJECTIVE

To assess the long-term maintenance of analgesia induced by high-frequency repetitive transcranial magnetic stimulation (rTMS) of the motor cortex contralateral to pain in a naturalistic study of patients with chronic refractory facial pain.

METHODS

55 patients were included (cluster headache, n = 19; trigeminal neuropathic pain, n = 21; atypical facial pain, n = 15). The rTMS protocol consisted of an "induction phase" of one daily rTMS session for five days per week during two consecutive weeks, followed by a "maintenance phase" of two sessions during one week, then one session in weeks 4 and 6, and a monthly session for the next five months. In a subset of patients, navigated targeting was performed and session duration was shortened from 20-min to 10-min (with the same number of 2000 pulses per session). The analgesic effect of rTMS was assessed on a 0-10 visual numerical scale from 15 to 180 days after treatment initiation.

RESULTS

All pain measures significantly decreased from baseline to D15: the intensity of permanent pain (5.2 ± 1.6 to 3.2 ± 1.9) and paroxysmal pain (8.6 ± 1.5 to 4.5 ± 3.4), as well as the daily number of painful attacks (5.6 ± 3.1 to 2.3 ± 3.1). The percentage of responders (defined as pain score decrease ≥30%) was 73% at D15 and dropped to 40% at D180. The analgesic effect was similar regardless of the type of pain and was significantly lower when session duration was shortened, irrespective of the number of pulses.

CONCLUSION

This long-term maintenance rTMS protocol can be a therapeutic option in the clinical management of patients with chronic refractory facial pain, including cluster headache. However, only part of the patients respond to this technique and session duration should not be reduced.

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.

Licit and illicit drug use in cluster headache

Cluster headache patients seem to use more licit and illicit substances than the general population. The epidemiologic data supporting this is growing. We included the licit drugs in this review because their use seems to be driven by the same addiction mechanisms leading to illicit drug abuse. Some drugs may be used in an attempt to treat cluster headache, especially cocaine and hallucinogens. Drug exposure may also play a role in CH pathophysiology, as suggested by interesting data on tobacco use and second-hand smoke exposure. A common factor may contribute both to CH and drug use predisposition. Genetic factors may be at play, and the dopaminergic and orexinergic pathways could be targeted for future studies.

Emerging therapies for chronic migraine

Not all chronic migraines are medication-overuse headaches and so the challenge is how to treat them. Currently available pharmacological therapies may be ineffective or they are abandoned because of intolerable side effects. There is still much room for novel therapeutic approaches in those with drug refractory migraine (RM). Occipital nerve stimulation (ONS) and botulinum toxin type A have finally gained a level of evidence based on the results of RCTs and pooled analysis, which by and large have shown at least a modest but valuable therapeutic effect. For a long time, these two approaches were only supported by clinical experience and open-label studies. Considering the disabling nature of migraine disorder, the large prevalence and serious impact on health-related quality of life and health care costs, any degree of response to treatment is acceptable and welcomed by the patient. An important issues for future studies would be better patient selection when finding candidates for each procedure.

Introduction to neuropathic pain syndromes

Chronic pain impairs the quality of life for millions of individuals and therefore presents a serious ongoing challenge to clinicians and researchers. Debilitating chronic pain syndromes cost the US economy more than $600 billion per year. This article provides an overview of the epidemiology, clinical presentation, and treatment outcomes for craniofacial, spinal, and peripheral neurologic pain syndromes. Although the authors recognize that the diagnosis and treatment of the chronic forms of neuropathic pain syndromes represent a clinical challenge, there is an urgent need for standardized classification systems, improved epidemiologic data, and reliable treatment outcomes data.

Stimulation of the sphenopalatine ganglion in intractable cluster headache: expert consensus on patient selection and standards of care

CONTEXT AND OVERVIEW

Chronic cluster headache (CCH) is a debilitating headache disorder with a significant impairment of the patients' lives. Within the past decade, various invasive neuromodulatory approaches have been proposed for the treatment of CCH refractory to standard preventive drug, but only very few randomized controlled studies exist in the field of neuromodulation for the treatment of drug-refractory headaches. Based on the prominent role of the cranial parasympathetic system in acute cluster headache attacks, high-frequency sphenopalatine ganglion (SPG) stimulation has been shown to abort ongoing attacks in some patients in a first small study. As preventive effects of SPG-stimulation have been suggested and the rate of long-term side effects was moderate, SPG stimulation appears to be a promising new treatment strategy.

AIMS AND CONCLUSION

As SPG stimulation is effective in some patients and the first commercially available CE-marked SPG neurostimulator system has been introduced for cluster headache, patient selection and care should be standardized to ensure maximal efficacy and safety. As only limited data have been published on SPG stimulation, standards of care based on expert consensus are proposed to ensure homogeneous patient selection and treatment across international headache centres. Given that SPG stimulation is still a novel approach, all expert-based consensus on patient selection and standards of care should be re-reviewed when more long-term data are available.

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.