Pearls and pitfalls: neurostimulation in headache

Transdermal auricular vagus stimulation for the treatment of postural tachycardia syndrome

Postural Tachycardia Syndrome (POTS) is a chronic disorder characterized by symptoms of orthostatic intolerance such as fatigue, lightheadedness, dizziness, palpitations, dyspnea, chest discomfort and remarkable tachycardia upon standing. Non-invasive transdermal vagal stimulators have been applied for the treatment of epilepsy, anxiety, depression, headache, and chronic pain syndromes. Anti-inflammatory and immunomodulating effects after transdermal vagal stimulation raised interest for applications in other diseases. Patients with sympathetic overactivity, reduced cardiac vagal drive and presence of systemic inflammation like POTS may benefit from tVNS. This article will address crucial methodological aspects of tVNS and provide preliminary results of its acute and chronic use in POTS, with regards to its potential effectiveness on autonomic symptoms reduction and heart rate modulation.

Non-Invasive Neurostimulation Methods for Acute and Preventive Migraine Treatment-A Narrative Review

Neurostimulation methods have now been studied for more than 20 years in migraine treatment. They can be divided into invasive and non-invasive methods. In this narrative review, the non-invasive methods are presented. The most commonly studied and used methods are vagal nerve stimulation, electric peripheral nerve stimulation, transcranial magnetic stimulation, and transcranial direct current stimulation. Other stimulation techniques, including mechanical stimulation, play only a minor role. Nearly all methods have been studied for acute attack treatment and for the prophylactic treatment of migraine. The evidence of efficacy is poor for most procedures, since no stimulation device is based on consistently positive, blinded, controlled trials with a sufficient number of patients. In addition, most studies on these devices enrolled patients who did not respond sufficiently to oral drug treatment, and so the role of neurostimulation in an average population of migraine patients is unknown. In the future, it is very important to conduct large, properly blinded and controlled trials performed by independent researchers. Otherwise, neurostimulation methods will only play a very minor role in the treatment of migraine.

The role of left prefrontal transcranial magnetic stimulation in episodic migraine prophylaxis

Objective

The aim of the study was to examine the prophylactic role of repetitive transcranial magnetic stimulation (rTMS) on the frequency, and severity of migraine attacks in episodic migraineurs who failed medical treatment.

Methods

A randomized double-blinded placebo-controlled study was designed to assess the effect of 5 Hz rTMS applied over the left dorsolateral prefrontal cortex (LDLPFC ) in 33 migraineurs. Patients were followed up for 1 month before receiving rTMS, and for another month after the sessions by a headache diary. The primary outcome measure was the achievement of 50% reduction in the number of migraine attacks. Secondary outcome measures included migraine days, assessment of migraine attack severity, disability by HIT-6, and side-effects to the procedure.

Results

The study revealed that 69.2% of the active treatment group achieved 50% or more reduction in the number of migraine attacks versus 25% of cases in the control group (p = 0.02). The absolute number of migraine attacks was reduced by 3.1 vs 1.5 in the active and control group, respectively. The number of cases with severe HIT-6 scores was reduced by 46.2% in active treatment group versus a 7.1% reduction in the control group (p = 0.02).

Conclusion

High-frequency rTMS applied to LDLPFC can reduce the number of migraine attacks by 50% or more in almost 70% of a sample of episodic migraineurs with a concomitant decrease in functional disability.

Trial registration

ClinicalTrials.gov, Identifier: NCT04031781. Registered 23 July 2019—retrospectively registered at https://clinicaltrials.gov/ct2/show/NCT04031781?term=Migraine+Prophylaxis&recrs=ce&type=Intr&cond=Migraine&rank=9

Low frequency activation of the sphenopalatine ganglion does not induce migraine-like attacks in migraine patients

Introduction

Cephalic autonomic symptoms occur in 27‒73% of migraine patients during attacks. The role of parasympathetic activation in migraine attack initiation remains elusive. Low frequency stimulation of the sphenopalatine ganglion increases parasympathetic outflow. In this study, we hypothesized that low frequency stimulation of the sphenopalatine ganglion would provoke migraine-like attacks in migraine patients.

Methods

In a double-blind randomized sham-controlled crossover study, 12 migraine patients with a sphenopalatine ganglion neurostimulator received low frequency or sham stimulation for 30 min on two separate days. We recorded headache characteristics, cephalic autonomic symptoms, ipsilateral mechanical perception and pain thresholds, mean blood flow velocity in the middle cerebral artery (VMCA) and diameter of the superficial temporal artery during and after stimulation.

Results

Five patients (42%) reported a migraine-like attack after low frequency stimulation compared to six patients (50%) after sham ( p = 1.000). We found a significant increase in mechanical detection thresholds during low frequency stimulation compared to baseline ( p = 0.007). Occurrence of cephalic autonomic symptoms and changes in mechanical perception thresholds, VMCA and diameter of the superficial temporal artery showed no difference between low frequency stimulation compared to sham ( p = 0.533).

Conclusion

Low frequency stimulation of the sphenopalatine ganglion did not induce migraine-like attacks or autonomic symptoms in migraine patients. These data suggest that increased parasympathetic outflow by the sphenopalatine ganglion neurostimulator does not initiate migraine-like attacks. Study protocol: ClinicalTrials.gov registration number NCT02510742

Headaches in the medieval Medical School of Salerno

PREMISE

Headaches are a serious public health concern of our days, affecting about 50% of the world's adult population. However, such a plague is not limited to the modern era, since ancient archaeological, written, religious and cultural evidences testify to countless attempts to face such disorders from medical, neurosurgical, psychological and sociological perspectives.

BACKGROUND

Substantially, the Hippocratic and Galenic theories about headache physiopathology remained predominant up to the 17th century, when the vascular theory of migraine was introduced by Thomas Willis and then evolved into the actual neurovascular hypothesis. The medieval Medical School of Salerno, in southern Italy, where the Greco-Roman medical doctrine was deeply affected by the medio-oriental influence, gave particular attention to both prevention and treatment of headaches.

CONCLUSION

The texts of the School, a milestone in the literature of medicine, translated into different languages and widespread throughout Europe for centuries, provide numerous useful recipes and ingredients with an actually proven pharmacological efficacy.

Treatment of migraine attacks and prevention of migraine: Guidelines by the German Migraine and Headache Society and the German Society of Neurology

In collaboration with some of the leading headache centres in Germany, Switzerland and Austria, we have established new guidelines for the treatment of migraine attacks and the prevention of migraine. A thorough literature research of the last 10 years has been the basis of the current recommendations. At the beginning, we present therapeutic novelties, followed by a summary of all recommendations. After an introduction, we cover topics like drug therapy and practical experience, non-effective medication, migraine prevention, interventional methods, non-medicational and psychological methods for prevention and therapies without proof of efficacy.

Vagus nerve stimulation: An evolving adjunctive treatment for cardiac disease

The vagus nerve is a major component of the autonomic nervous system and plays a critical role in many body functions including for example, speech, swallowing, heart rate and respiratory control, gastric secretion, and intestinal motility. Vagus nerve stimulation (VNS) refers to any technique that stimulates the vagus nerve, with electrical stimulation being the most important. Implantable devices for VNS are approved therapy for refractory epilepsy and for treatment-resistant depression. In the case of heart disease applications, implantable VNS has been shown to be beneficial for treating heart failure in both preclinical and clinical studies. Adverse effects of implantable VNS therapy systems are generally associated with the implantation procedure or continuous on-off stimulation. The most serious implantation-associated adverse effect is infection. The effectiveness of non-invasive transcutaneous VNS for epilepsy, depression, primary headaches, heart failure, and other conditions remains under investigation. VNS merits further study for its potentially favorable effects on cardiovascular disease, especially heart failure.

Long-Term Outcome of Patients With Intractable Chronic Cluster Headache Treated With Injection of Onabotulinum Toxin A Toward the Sphenopalatine Ganglion - An Observational Study

Objectives

To investigate long‐term outcomes in per‐protocol chronic cluster headache patients (n = 7), 18 and 24 months after participation in “Pilot study of sphenopalatine injection of onabotulinumtoxinA for the treatment of intractable chronic cluster headache.”

Methods

Data were collected prospectively through headache diaries, HIT‐6, and open questionnaire forms at 18 and 24 months after the first treatment. Patients had access to repeated injections when needed.

Results

An overall significant reduction in cluster headache attack frequency per month (57.3 ± 35.6 at baseline vs 12.4 ± 15.2 at month 18 and 24.6 ± 19.2 at month 24) was found. In addition, there was a reduction in attacks with severe and unbearably intensity (50.0 ± 38.3 at baseline vs 10.1 ± 14.7 at month 18 and 16.6 ± 13.7 at month 24) and an increase in attack free days (4.2 ± 5.9 at baseline vs 19.1 ± 9.4 at month 18 and 12.9 ± 8.8 at month 24).

Conclusions

Our findings suggest sustained headache relief after repeated onabotulinumtoxinA injections toward the sphenopalatine ganglion in intractable chronic cluster headache. A placebo‐controlled trial with long‐term follow‐up is warranted.

Non-invasive vagus nerve stimulation (nVNS) as symptomatic treatment of migraine in young patients: a preliminary safety study

Recent clinical experiences and clinical trials have demonstrated the safety, tolerability, and efficacy of non-invasive vagus nerve stimulation (nVNS; gammaCore^®) for the acute and prophylactic treatment of migraine. nVNS has a favorable adverse event profile, making it an attractive option for sensitive patient populations. We explored the safety, tolerability, and efficacy of nVNS as acute migraine treatment in adolescents. A group of adolescent patients suffering from migraine without aura were trained to use gammaCore to manage their migraine attacks. 46.8% of the treated migraine attacks (22/47) were considered successfully treated and did not require any rescue medication. No device-related adverse events were recorded. This preliminary study suggests that nVNS may represent a safe, well-tolerated, and effective for acute migraine treatment in adolescents.

Cranial parasympathetic activation induces autonomic symptoms but no cluster headache attacks

Background

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

Methods

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

Results

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

Conclusion

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

Study protocol

ClinicalTrials.gov registration number NCT02510729

Abnormal cortical asymmetry as a target for neuromodulation in neuropsychiatric disorders: A narrative review and concept proposal

Recent advances in knowledge relating to the organization of neural circuitry in the human brain have increased understanding of disorders involving brain circuit asymmetry. These asymmetries, which can be measured and identified utilizing EEG and LORETA analysis techniques, may be a factor in mental disorders. New treatments involving non-invasive brain stimulation (NIBS), including trans-cranial magnetic stimulation, direct current stimulation and vagal nerve stimulation, have emerged in recent years. We propose that EEG identification of circuit asymmetry geometries can direct non-invasive brain stimulation more specifically for treatments of mental disorders. We describe as a narrative review new NIBS therapies that have been developed and delivered, and suggest that they are proving effective in certain patient groups. A brief narrative of influence of classical and operant conditioning of neurofeedback on EEG coherence, phase, abnormalities and Loreta's significance is provided. We also discuss the role of Heart rate variability and biofeedback in influencing EEG co-relates. Clinical evidence is at an early stage, but the basic science evidence and early case studies suggest that this may be a promising new modality for treating mental disorders and merits further research.

Central and Peripheral Neural Targets for Neurostimulation of Chronic Headaches

PURPOSE OF REVIEW

Chronic headache sufferers are estimated to be around 3% of the population. These patients have a high disease burden. When prophylactic treatments have low efficacy and tolerability, patients are in need of alternative therapeutic strategies and options.

RECENT FINDINGS

In the last decade, a number of neuromodulation procedures have been introduced as treatment of chronic intractable headache patients when pharmacological treatments fail or are not well tolerated. Neurostimulation of peripheral and central nervous system has been carried out, and now, various non-invasive and invasive stimulation devices are available. Non-invasive neurostimulation options include vagus nerve stimulation, supraorbital stimulation and single-pulse transcranial magnetic stimulation; invasive procedures include occipital nerve stimulation, sphenopalatine ganglion stimulation and hypothalamic deep brain stimulation. In many cases, results supporting their use derive from open-label series and small controlled trial studies. Lack of adequate placebo hampers adequate randomized controlled trials. In this paper, we give an overview on the main neurostimulation procedures in terms of results and putative mechanism of cation.

Inhibitory effect of high-frequency greater occipital nerve electrical stimulation on trigeminovascular nociceptive processing in rats

Electrical stimulation of the greater occipital nerve (GON) has recently shown promise as an effective non-pharmacological prophylactic therapy for drug-resistant chronic primary headaches, but the neurobiological mechanisms underlying its anticephalgic action are not elucidated. Considering that the spinal trigeminal nucleus (STN) is a key segmental structure playing a prominent role in pathophysiology of headaches, in the present study we evaluated the effects of GON electrical stimulation on ongoing and evoked firing of the dura-sensitive STN neurons. The experiments were carried out on urethane/chloralose-anesthetized, paralyzed and artificially ventilated male Wistar rats. Extracellular recordings were made from 11 neurons within the caudal part of the STN that received convergent input from the ipsilateral facial cutaneous receptive fields, dura mater and GON. In each experiment, five various combinations of the GON stimulation frequency (50, 75, 100 Hz) and intensity (1, 3, 6 V) were tested successively in 10 min interval. At all parameter sets, preconditioning GON stimulation (250 ms train of pulses applied before each recording) produced suppression of both the ongoing activity of the STN neurons and their responses to electrical stimulation of the dura mater. The inhibitory effect depended mostly on the GON stimulation intensity, being maximally pronounced when a stimulus of 6 V was applied. Thus, the GON stimulation-induced inhibition of trigeminovascular nociceptive processing at the level of STN has been demonstrated for the first time. The data obtained can contribute to a deeper understanding of neurophysiological mechanisms underlying the therapeutic efficacy of GON stimulation in primary headaches.

Stimulation-Based Control of Dynamic Brain Networks

The ability to modulate brain states using targeted stimulation is increasingly being employed to treat neurological disorders and to enhance human performance. Despite the growing interest in brain stimulation as a form of neuromodulation, much remains unknown about the network-level impact of these focal perturbations. To study the system wide impact of regional stimulation, we employ a data-driven computational model of nonlinear brain dynamics to systematically explore the effects of targeted stimulation. Validating predictions from network control theory, we uncover the relationship between regional controllability and the focal versus global impact of stimulation, and we relate these findings to differences in the underlying network architecture. Finally, by mapping brain regions to cognitive systems, we observe that the default mode system imparts large global change despite being highly constrained by structural connectivity. This work forms an important step towards the development of personalized stimulation protocols for medical treatment or performance enhancement.

Brain stimulation is increasingly used in clinical settings to treat neurological disorders, but much remains unknown about how stimulation to a single brain region impacts large-scale, brain network activity. Using structural neuroimaging scans, we create computational models of brain dynamics for eight participants to explore how structure-function relationships constrain the effect of stimulation to a single region on the brain as a whole. Our results show that network control theory can be used to predict if the effects of stimulation remain focal or spread globally, and structural connectivity differentially constrains the effects of regional stimulation. Additionally, we study how stimulation of different cognitive systems spreads throughout the brain and find that stimulation of regions within the default mode network provide a mechanism to impart large change in overall brain dynamics through a densely connected structural network. By revealing how the stimulation of different brain regions and cognitive systems spreads differently through the brain, we provide a modeling framework to develop stimulation protocols to personalize medical treatments, enable performance enhancements, and facilitate cortical plasticity.

Pilot study of sphenopalatine injection of onabotulinumtoxinA for the treatment of intractable chronic cluster headache

OBJECTIVE

The main object of this pilot study was to investigate the safety of administering onabotulinumtoxinA (BTA) towards the sphenopalatine ganglion (SPG) in intractable chronic cluster headache. Efficacy data were also collected to provide indication on whether future placebo-controlled studies should be performed.

METHOD

In a prospective, open-label, uncontrolled study, we performed a single injection of 25 IU (n = 5) or 50 IU BTA (n = 5) towards the SPG in 10 patients with intractable chronic cluster headache with a follow-up of 24 weeks. The primary outcome was adverse events (AEs) and the main efficacy outcome was attack frequency in weeks 3 and 4 post-treatment.

RESULTS

A total of 11 AEs were registered. There was one severe adverse event (SAE): posterior epistaxis. The number of cluster headache attacks (main efficacy outcome) was statistically significantly reduced in the intention-to-treat analysis from 18 ± 12 per week in baseline to 11 ± 14 (p = 0.038) in weeks 3 and 4, and five out of 10 patients had at least 50% reduction of attack frequency compared to baseline. The cluster attack frequency was significantly reduced for five out of six months post-treatment.

CONCLUSION

Randomised, placebo-controlled studies are warranted to establish the potential of this possible novel treatment of cluster headache.

The phenotype of migraine with unilateral cranial autonomic symptoms documents increased peripheral and central trigeminal sensitization. A case series of 757 patients

BACKGROUND

Migraine with unilateral cranial autonomic symptoms (UAS) is a putative migraine endophenotype with convincing response to trigeminal-targeted treatments that still needs a thorough characterization.

OBJECTIVE

The objective of this article is to carefully investigate the clinical phenotype of migraine with UAS in a large group of patients for more accurate migraine diagnoses, improved clinical management, and better outcome prediction.

METHODS

We studied 757 consecutive episodic and chronic migraineurs in a tertiary headache clinic with face-to-face interviews, detailing in depth their lifestyle, sociodemographic and headache characteristics.

RESULTS

Migraineurs with UAS (37.4%) differed from the general migraine population with respect to longer attack duration (OR = 2.47, p < 0.02, having >72-hour long attacks), more strictly unilateral (OR = 3.18, p < 0.001) and severe headache (OR = 1.72, p = 0.011), more frequent allodynia (OR = 3.03, p < 0.001) and photophobia (OR = 1.87, p = 0.019).

CONCLUSIONS

Migraine patients with UAS are characterized not only by symptoms due to intense peripheral trigeminal activation but also to central sensitization. Our study broadens the knowledge on the clinical and phenotypic characteristics of migraine with UAS, suggests pathophysiological implications, and supports the need for future prospective clinical studies.

Managing Chronic Headache Disorders

Headaches are a very common disorder, more common than asthma and diabetes combined. Migraine is the most common headache disorder, but it remains underdiagnosed and therefore undertreated. The treatment of migraines is divided into acute and prophylaxis. Patients who are experiencing 8 or more headaches a month or those who experience disability with their headaches as determined by the Migraine Disability Assistance Score or MIDAS should be placed on prophylaxis.

Update of Inpatient Treatment for Refractory Chronic Daily Headache

Chronic daily headache (CDH) is a group of headache disorders, in which headaches occur daily or near-daily (>15 days per month) and last for more than 3 months. Important CDH subtypes include chronic migraine, chronic tension-type headache, hemicrania continua, and new daily persistent headache. Other headaches with shorter durations (<4 h/day) are usually not included in CDH. Common comorbidities of CDH are medication overuse headache and various psychiatric disorders, such as depression and anxiety. Indications of inpatient treatment for CDH patients include poor responses to outpatient management, need for detoxification for overuse of specific medications (particularly opioids and barbiturates), and severe psychiatric comorbidities. Inpatient treatment usually involves stopping acute pain, preventing future attacks, and detoxifying medication overuse if present. Multidisciplinary integrated care that includes medical staff from different disciplines (e.g., psychiatry, clinical psychology, and physical therapy) has been recommended. The outcomes of inpatient treatment are satisfactory in terms of decreasing headache intensity or frequency, withdrawal from medication overuse, reducing disability, and improving life quality, although long-term relapse is not uncommon. In conclusion, inpatient treatment may be useful for select patients with refractory CDH and should be incorporated in a holistic headache care program.

Non-invasive vagus nerve stimulation for acute treatment of high-frequency and chronic migraine: an open-label study

BACKGROUND

The treatment of migraine headache is challenging given the lack of a standardized approach to care, unsatisfactory response rates, and medication overuse. Neuromodulation therapy has gained interest as an alternative to pharmacologic therapy for primary headache disorders. This study investigated the effects of non-invasive vagus nerve stimulation (nVNS) in patients with high-frequency episodic migraine (HFEM) and chronic migraine (CM).

FINDINGS

In this open-label, single-arm, multicenter study, patients with HFEM or CM self-treated up to 3 consecutive mild or moderate migraine attacks that occurred during a 2-week period by delivering two 120-s doses of nVNS at 3-min intervals to the right cervical branch of the vagus nerve. Of the 50 migraineurs enrolled (CM/HFEM: 36/14), 48 treated 131 attacks. The proportion of patients reporting pain relief, defined as a ≥50% reduction in visual analog scale (VAS) score, was 56.3% at 1 h and 64.6% at 2 h. Of these patients, 35.4% and 39.6% achieved pain-free status (VAS = 0) at 1 and 2 h, respectively. When all attacks (N = 131) were considered, the pain-relief rate was 38.2% at 1 h and 51.1% at 2 h, whereas the pain-free rate was 17.6% at 1 h and 22.9% at 2 h. Treatment with nVNS was safe and well tolerated.

CONCLUSION

Non-invasive vagus nerve stimulation may be effective as acute treatment for HFEM or CM and may help to reduce medication overuse and medication-associated adverse events.

Medication overuse and chronic migraine: a critical review according to clinical pharmacology

INTRODUCTION

Chronic migraine is often complicated by medication-overuse headache (MOH), a headache due to excessive intake of acute medications. Chronic migraine and MOH are serious and disabling disorders. Since chronic migraine derives from the progression of originally episodic migraine, the fundamental therapeutic strategy is prevention. This narrative review describes how to try to prevent the development of MOH and how to manage it once it has appeared.

AREAS COVERED

A PubMed database search (from 1988 to January 2015) and a review of published studies on chronic migraine and MOH were conducted.

EXPERT OPINION

In spite of progress in migraine treatment, the prevalence of chronic headaches and MOH has not changed in the course of time. Today, a large number of migraine patients have turned to numerous expert physicians and experienced all sorts of prophylactic treatments without decisive benefits. Their condition seems to have crystallized even more as chronic and intractable. This means that to prevent chronification and MOH, we need more effective drugs and better strategies to use them. In particular, we must detect disease biomarkers and predictive factors for drug response that allow for personalized treatment when migraine is still episodic and make analgesic overuse pointless.

Advanced technologies and novel neurostimulation targets in trigeminal autonomic cephalalgias

The trigeminal autonomic cephalalgias (TACs) are a group of rare but disabling primary headache disorders. Their management is challenging, since only few effective treatments are available and high doses may be required to control the headache, compromising patients' adherence to treatments. A significant minority of patients, who fail to respond to or tolerate established treatments, are left with enormous level of disability and disruption to their quality of life. A growing body of evidence demonstrates the efficacy of central and peripheral neuromodulation approaches for management of patients with refractory TACs. In view of the potential risks related to deep brain stimulation of the posterior hypothalamic region, occipital nerve stimulation is currently considered the first treatment option for refractory chronic TACs. However, in view of the presence of paraesthesia induced by the stimulator, no robust controlled trials have been possible so far. Additionally, the equipment used for occipital nerve stimulation is not designed specifically for peripheral nerve stimulation, thus a significant proportion of patients experience device-related complications that often require surgical revisions. To overcome these issues, new neurostimulation technologies using less invasive or non-invasive approaches and modulating different neuroanatomical targets have been recently studied.

[Therapy of trigeminal autonomic headaches]

Trigeminal autonomic cephalgias (TAC) are characterized by severe and strictly unilateral headaches with a frontotemporal and periorbital preponderance in combination with ipsilateral cranial autonomic symptoms, such as lacrimation, conjunctival injection, rhinorrhea, nasal congestion, and restlessness or agitation. One main differentiating factor is the duration of painful attacks. While attacks typically last 5 s to 10 min in SUNCT syndrome (short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing), paroxysmal hemicrania lasts 2-30 min and cluster headaches 15-180 min. Hemicrania continua represents a continuous TAC variant. From a therapeutic view, TACs differ substantially. Lamotrigine is used as first-choice prevention in SUNCT syndrome and indometacin in paroxysmal hemicrania. For cluster headaches, acute therapy with inhaled pure oxygen and fast-acting triptans (sumatriptan s.c. and intranasal zolmitriptan) is equally important to short-term preventive therapy with methysergide and cortisone and long-term prophylactic treatment comprising verapamil as drug of first choice and lithium carbonate and topiramate as drugs of second choice. In refractory cases of chronic cluster headache, neuromodulatory approaches such as occipital nerve stimulation and sphenopalatine ganglion stimulation are increasingly applied.

Surgically implanted and non-invasive vagus nerve stimulation: a review of efficacy, safety and tolerability

Vagus nerve stimulation (VNS) is effective in refractory epilepsy and depression and is being investigated in heart failure, headache, gastric motility disorders and asthma. The first VNS device required surgical implantation of electrodes and a stimulator. Adverse events (AEs) are generally associated with implantation or continuous on-off stimulation. Infection is the most serious implantation-associated AE. Bradycardia and asystole have also been described during implantation, as has vocal cord paresis, which can last up to 6 months and depends on surgical skill and experience. The most frequent stimulation-associated AEs include voice alteration, paresthesia, cough, headache, dyspnea, pharyngitis and pain, which may require a decrease in stimulation strength or intermittent or permanent device deactivation. Newer non-invasive VNS delivery systems do not require surgery and permit patient-administered stimulation on demand. These non-invasive VNS systems improve the safety and tolerability of VNS, making it more accessible and facilitating further investigations across a wider range of uses.

Value of intra- and post-operative cone beam computed tomography (CBCT) for positioning control of a sphenopalatine ganglion neurostimulator in patients with chronic cluster headache

INTRODUCTION

The objective of this study was to determine whether postoperative control of the neurostimulator placement within the pterygopalatine fossa (PPF) by means of 3-dimensional (3D) cone beam computed tomography (CBCT) was of therapeutic relevance compared to intraoperative CBCT imaging alone.

MATERIAL AND METHODS

Immediately after implantation of the sphenopalatine ganglion (SPG) neurostimulator, intraoperative CBCT datasets were generated in order to visualize the position of the probe within the PPF. Postoperatively, all patients received a CBCT for comparison with intraoperatively acquired radiographs.

RESULTS

Twenty-four patients with cluster headache (CH) received an SPG neurostimulator. In 4 patients, postoperative CBCT images detected misplacement not found in intraoperative CBCT. In 3 cases, electrode tips were misplaced into the maxillary sinus and in 1 case into the apex of the PPF superior to the suspected location of the SPG. Immediate revision with successful repositioning within 3 days was done in 2 patients and a deferred reimplantation in 1 patient within 6 months. One patient declined revision.

CONCLUSION

We were able to demonstrate the clinical value of postoperative dental CBCT imaging with a wide region of interest (ROI) due to a superior image quality compared with that achieved with intraoperative medical CBCT. Although intraoperative 3D CBCT imaging of electrode placement is helpful in the acute surgical setting, resolution is, at present, too low to safely exclude misplacement, especially in the maxillary sinus. High-resolution postoperative dental CBCT allows rapid detection and revision of electrode misplacement, thereby avoiding readmission and recurrent tissue trauma.

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.

Nociception specific supraorbital nerve stimulation may prevent cluster headache attacks: serendipity in a blink reflex study

BACKGROUND

In cluster headache, neuromodulation is offered when patients are refractory to pharmacological prophylaxis. Non-invasive peripheral neuromodulatory approaches are of interest. We will focus on these and particularly on nociception specific, transcutaneous supraorbital nerve stimulation.

METHODS

In a study using the nociception specific blink reflex, we made a serendipitous discovery, notably the potential prophylactic effect of bilateral, time contingent, nociception specific, transcutaneous stimulation of the supraorbital nerve.

RESULTS

We report on a case series of seven cluster headache patients, in whom attacks seemed to disappear during repeated stimulation of the supraorbital nerves. Three patients stopped experiencing attacks since study participation.

CONCLUSIONS

Bilateral, time contingent, nociception specific, transcutaneous supraorbital nerve stimulation may have a prophylactic effect in episodic and chronic cluster headache. Given its limited side effects and its non-invasive nature, further studies to investigate this potential peripheral neuromodulatory approach for both episodic and chronic cluster headache are warranted.

Sleep-related headache and its management

OPINION STATEMENT

Sleep and headache have both generated curiosity within the human mind for centuries. The relationship between headache and sleep disorders is very complex. While Lieving in 1873 first observed that headaches were linked to sleep, Dexter and Weitzman in 1970 described the relationship between headache and sleep stages. Though our understanding of sleep and headache relationship has improved over the years with expanding knowledge in both fields and assessment tools such as polysomnography, it is still poorly understood. Headache and sleep have an interdependent relationship. Headache may be intrinsically related to sleep (migraine with and without aura, cluster headache, hypnic headache, and paroxysmal hemicrania), may cause sleep disturbance (chronic migraine, chronic tension-type headache, and medication overuse headache) or a manifestation of a sleep disorder like obstructive sleep apnea. Headache and sleep disorder may be a common manifestation of systemic dysfunction-like anemia and hypoxemia. Headaches may occur during sleep, after sleep, and in relation to different sleep stages. Lack of sleep and excessive sleep are both considered triggers for migraine. Insomnia is more common among chronic headache patients. Experimental data suggest that there is a common anatomic and physiologic substrate. There is overwhelming evidence that cluster headache and hypnic headaches are chronobiological disorders with strong association with sleep and involvement of hypothalamus. Cluster headache shows a circadian and circannual rhythmicity while hypnic headache shows an alarm clock pattern. There is also a preferential occurrence of cluster headache, hypnic headache, and paroxysmal hemicrania during REM sleep. Silencing of anti-nociceptive network of periaqueductal grey (PAG), locus ceruleus and dorsal raphe nucleus doing REM sleep may explain the preferential pattern. Sleep related headaches can be classified into (1) headaches with high association with obstructive sleep apnea, which includes cluster headache, hypnic headache, and headache related to obstructive sleep apnea; and (2) headaches with high prevalence of insomnia, medication overuse, and psychiatric comorbidity including chronic migraine and chronic tension-type headache. The initial step in the management of sleep related headache is proper diagnosis with exclusion of secondary headaches. Screening for sleep disorders with the use of proper tests including polysomnography and referral to sleep clinic, when appropriate is very helpful. Control of individual episode in less than 2 hours should be the initial goal using measures to abort and prevent a relapse. Cluster headache responds very well to injectable Imitrex and oxygen. Verapamil, steroids and lithium are used for preventive treatment of cluster headache. Intractable cluster headache patients have responded to hypothalamic deep brain stimulation. Hypnic headache patients respond to nightly caffeine, indomethacin, and lithium. Paroxysmal hemicrania responds very well to indomethacin. Early morning headaches associated with obstructive sleep apnea respond to CPAP or BiPAP with complete resolution of headache within a month. Patient education and lifestyle modification play a significant role in overall success of the treatment. Chronic tension-type headache and chronic migraine have high prevalence of insomnia and comorbid psychiatric disorders, which require behavioral insomnia treatment and medication if needed along with psychiatric evaluation. Apart from the abortive treatment tailored to the headache types, - such as triptans and DHE 45 for migraine and nonsteroidal anti-inflammatory medication for chronic tension-type headache, preventive treatment with different class of medications including antiepileptics (Topamax and Depakote), calcium channel blockers (verapamil), beta blockers (propranolol), antidepressants (amitriptyline), and Botox may be used depending upon the comorbid conditions.