Advances and challenges in neurostimulation for headaches

Microfabrication Technologies for Nanoinvasive and High-Resolution Magnetic Neuromodulation

The increasing demand for precise neuromodulation necessitates advancements in techniques to achieve higher spatial resolution. Magnetic stimulation, offering low signal attenuation and minimal tissue damage, plays a significant role in neuromodulation. Conventional transcranial magnetic stimulation (TMS), though noninvasive, lacks the spatial resolution and neuron selectivity required for spatially precise neuromodulation. To address these limitations, the next generation of magnetic neurostimulation technologies aims to achieve submillimeter-resolution and selective neuromodulation with high temporal resolution. Invasive and nanoinvasive magnetic neurostimulation are two next-generation approaches: invasive methods use implantable microcoils, while nanoinvasive methods use magnetic nanoparticles (MNPs) to achieve high spatial and temporal resolution of magnetic neuromodulation. This review will introduce the working principles, technical details, coil designs, and potential future developments of these approaches from an engineering perspective. Furthermore, the review will discuss state-of-the-art microfabrication in depth due to its irreplaceable role in realizing next-generation magnetic neuromodulation. In addition to reviewing magnetic neuromodulation, this review will cover through-silicon vias (TSV), surface micromachining, photolithography, direct writing, and other fabrication technologies, supported by case studies, providing a framework for the integration of magnetic neuromodulation and microelectronics technologies.

Association of atopic dermatitis and headache disorder: a systematic review and meta-analyses

Background

Growing evidence suggests that headache disorders and atopic dermatitis share similar pathological mechanisms and risk factors. The aim of this study was to assess the risk for headache disorders in patients with atopic dermatitis.

Methods

We systematically searched the PubMed and Embase databases from inception to December 1, 2023, for observational studies that examined risk of migraine in subjects with atopic dermatitis. Risk estimates from individual studies were pooled using random-effects models.

Results

Ten studies with 12,717,747 subjects were included in the meta-analysis. Our results showed that patients with atopic dermatitis were associated with a higher risk of headache disorder (OR, 1.46, 95% CI = 1.36-1.56; P < 0.001; I2 = 98%) or migraine (OR, 1.32, 95% CI = 1.18-1.47; P < 0.001; I2 = 98.9%). Most of the results of the subgroup analyses were consistent with the overall results.

Conclusion

The findings of this meta-analysis suggest that atopic dermatitis is a potential risk indicator for headache disorder or migraine. Further studies are still needed to verify our findings due to the substantial heterogeneity in our analyses.

Deep Brain Stimulation for Chronic Cluster Headaches: A Systematic Review and Meta-Analysis

BACKGROUND

Chronic cluster headache (CCH) is a severe and debilitating sub-type of trigeminal autonomic cephalalgia that can be resistant to medical management and associated with significant impairment in quality of life. Studies of deep brain stimulation (DBS) for CCH have provided promising results but have not been assessed in a comprehensive systematic review/meta-analysis.

OBJECTIVE

The objective was to perform a systematic literature review and meta-analysis of patients with CCH treated with DBS to provide insight on safety and efficacy.

METHODS

A systematic review and meta-analysis were performed according to PRISMA 2020 guidelines. 16 studies were included in final analysis. A random-effects model was used to meta-analyze data.

RESULTS

Sixteen studies reported 108 cases for data extraction and analysis. DBS was feasible in >99% of cases and was performed either awake or asleep. Meta-analysis revealed that the mean difference in headache attack frequency and headache intensity after DBS were statistically significant (p < 0.0001). Utilization of microelectrode recording was associated with statistically significant improvement in headache intensity postoperatively (p = 0.006). The average overall follow-up period was 45.4 months and ranged from 1 to 144 months. Death occurred in <1%. The rate of major complications was 16.67%.

CONCLUSIONS

DBS for CCHs is a feasible surgical technique with a reasonable safety profile that can be successfully performed either awake or asleep. In carefully selected patients, approximately 70% of patients achieve excellent control of their headaches.

Literature Review: Pericranial Nerve Blocks for Chronic Migraines

Purpose of Review

Headaches, especially migraines, are one of the most pervasive neurological disorders affecting up to 15.9% of the population. Current methods of migraine treatment include lifestyle changes, pharmacologic, and minimally invasive techniques such as peripheral nerve stimulation (PNS) and pericranial nerve blocks (PNB).

Recent Findings

PNBs are used to treat and prevent migraines and involves injection of local anesthetics with or without corticosteroids. PNBs include the greater occipital, supraorbital, supratrochlear, lesser occipital, auriculotemporal, sphenopalantine ganglion, and cervical root nerve blocks. Of the PNBs, the most extensively studied is the greater occipital nerve block (GONB) which has been shown to be an efficacious treatment for migraines, trigeminal neuralgia, hemi-crania continua, and post-lumbar puncture, post-concussive, cluster, and cervicogenic headaches but not medication overuse and chronic tension type headaches.

Summary

In this review, we aim to summarize the recent literature on PNBs and their efficacy in the treatment of migraines including a brief discussion of peripheral nerve stimulation.

An open-label observational study and meta-analysis of non-invasive vagus nerve stimulation in medically refractory chronic cluster headache

Background

Many patients with cluster headache (CH) are inadequately controlled by current treatment options. Non-invasive vagus nerve stimulation (nVNS) is reported to be effective in the management of CH though some studies suggest that it is ineffective.

Objective

To assess the safety and efficacy of nVNS in chronic cluster headache (CCH) patients.

Method

We prospectively analysed data from 40 patients with refractory CCH in this open-label, observational study. Patients were seen in tertiary headache clinics at the National Hospital for Neurology and Neurosurgery and trained to use nVNS as preventative therapy. Patients were reivewed at one month and then three-monthly from onset. The primary endpoint was number of patients achieving ≥50% reduction in attack frequency at 3  months. A meta-analysis of all published studies evaluating the efficacy of nVNS in CCH was also conducted. We searched MEDLINE and EMBASE for all studies investigating the use of nVNS as a preventive or adjunctive treatment for CCH with five or more participants. Combined mean difference and responder proportions with 95% confidence intervals (CI) were calculated from the included studies.

Results

17/40 patients (43%) achieved ≥50% reduction in attack frequency at 3  months. There was a significant reduction in monthly attack frequency from a baseline of 124 (±67) attacks to 79 (±63) attacks in month 3 (mean difference 44.7; 95% CI 25.1 to 64.3; p &lt; 0.001). In month 3, there was also a 1.2-point reduction in average severity from a baseline Verbal Rating Scale of 8/10 (95% CI 0.5 to 1.9; p = 0.001). Four studies, along with the present study, were deemed eligible for meta-analysis, which showed a responder proportion of 0.35 (95% CI 0.07 to 0.69, n = 137) and a mean reduction in headache frequency of 35.3 attacks per month (95% CI 11.0 to 59.6, n = 108), from a baseline of 105 (±22.7) attacks per month.

Conclusion

This study highlights the potential benefit of nVNS in CCH, with significant reductions in headache frequency and severity. To better characterise the effect, randomised sham-controlled trials are needed to confirm the beneficial response of VNS reported in some, but not all, open-label studies.

Symptoms and pathophysiology of cluster headache. Approach to combined occipital and supraorbital neurostimulation

Cluster headache (CH) is included under section 3 - Trigeminal autonomic cephalalgias (TAC) of the International Headache Society (IHS) classification. It is one of the most frequent, painful and disabling primary headaches. Acute and preventive pharmacological treatments are often poorly tolerated and of limited effectiveness. Due to improved understanding of the pathophysiology of CH, neuromodulation devices are now considered safe and effective options for preventive and acute treatment of CH. In this paper, we review the information available to date, and present the case of a patient with disabling cluster headache highly resistant to medical treatment who underwent implantation of a peripheral nerve neurostimulation system to stimulate the supraorbital nerves (SON) and greater occipital nerve (GON) in our Pain Unit. We also review the diagnostic criteria for CH, the state of the knowledge on the pathophysiology of CH, and the role played by neuromodulation in treating this condition.

Applications of transcranial magnetic stimulation in migraine: evidence from a scoping review

Transcranial magnetic stimulation (TMS), a non-invasive brain stimulation method, is trying to emerge as a migraine management strategy for both attack treatment and prevention. This scoping review presents 16 among single-pulse (to manage episodic and chronic migraine) and repetitive TMS randomized clinical trials (to manage chronic migraine). The works we reviewed suggest that TMS may be adopted as add-on therapy in those patients who are refractory to pharmacological therapy only with special arrangements for individualized treatment strategies or research. There are still limited clinical research programs and metaanalysis to promote routinely TMS employment, as TMS has been shown either to have no significant effects for any outcome or to be effective for migraine. These diverging conclusions depend on several biasing factors, including the lack of reliable, large, sham-controlled clinical trials, the dyshomogeneity in study designs (including the area of stimulation, the frequency of stimulation, the number of pulses, pulse intensity, and the number of sessions), patient selection criteria (migraine w/o aura, episodic and chronic migraine; TMS contraindication), and the lack of outcomes homogeneity and long-term real-world efficacy data. Therefore, in the future, it will be important to conduct larger randomized trials to confirm TMS usefulness in migraine management (acute attack and prophylactic treatment), identify those patients who may benefit from TMS, maybe independently of pharmacological treatments (i.e., using TMS as an alternative and not only as an add-on treatment). Otherwise, TMS will play a role in treating migraine only with special arrangements for individualized management strategies or research.

External Trigeminal Nerve Stimulation as a Non-pharmacological Option for the Prevention and Acute Treatment of Migraine

Migraine is a common condition affecting approximately 1.04 billion people worldwide. Despite the available pharmaceutical therapies, patients with migraine often prefer, or may require, non-medicinal treatments for their disease. External trigeminal nerve stimulation (e-TNS) is a non-invasive, non-drug device treatment approved by the US Food and Drug Administration for the prevention and acute treatment of migraine. The trigeminovascular system plays a key role in migraine pathophysiology; e-TNS percutaneously stimulates the supraorbital and supratrochlear branches of the ophthalmic division of the trigeminal nerve. This article reviews published studies of e-TNS in the prevention and acute treatment of migraine, highlights the versatility of e-TNS in individualizing migraine treatment and discusses future directions for research and clinical applications of e-TNS therapy.

Analgesic efficacy of a portable, disposable, and self-applied transcutaneous electrical nerve stimulation device during migraine attacks: A real-life randomized controlled trial

OBJECTIVE

The objective of this study was to evaluate the analgesic efficacy of a portable, disposable, and home self-applied transcutaneous electrical nerve stimulation (TENS) device during migraine attacks.

BACKGROUND

TENS has been used as a noninvasive treatment for migraine, but there are no reports on the outcomes following use of this treatment option for use at home during migraine attacks.

DESIGN AND METHODS

A double-blind, randomized controlled trial was conducted over 3 months, with monthly assessments. Active placebos (sham group) were in place and were allocated at a 1:1 ratio. Adult patients who had been diagnosed with migraine by a specialist were included. Pain intensity levels and functional disability were measured before and after the 20-min self-applied TENS intervention during the migraine attacks.

RESULTS

Seventy-four participants were randomly allocated to the sham and intervention groups. Although both groups of subjects reported lower pain scores, the intervention group showed a statistically significant reduction in pain scores compared to the sham group.

CONCLUSION

In our controlled trial, the use of a self-applied, TENS device is safe and effective in relieving pain associated with migraine attacks. Participants in the intervention group showed a statistically significant improvement in pain and functional disability scores. TENS has been used as a noninvasive treatment for migraine, but there are no reports on the outcomes following use of this treatment option for use at home during migraine attacks. This double-blind, randomized controlled trial had 2 groups: active-placebo and intervention. Seventy-four participants were randomly allocated. Participants in the intervention group showed a statistically significant improvement in pain and functional disability scores.

Geographical, Molecular, and Computational Analysis of Migraine-Causing Genes

Migraine is a re-occurring type of headache and causes moderate-to-severe pain that is troubling or pulsing. The pain occurs in half of the head, and common symptoms are photophobia, phonophobia, nausea, depression, anxiety, vomiting, etc. This study evaluates the prevalence of migraine and responsible genes through molecular modeling in the region of Bahawalpur, Pakistan. This research was aimed to determine the prevalence of migraine-causing genes in the population of Bahawalpur and also to do molecular and in-silico analysis of migraine-causing gene as no similar research was conducted before. The disease was characterized and diagnosed under the criteria of the Second Edition of the International Classification of Headache Disorders and molecular identification of migraine-causing genes, i.e. GRIA1, GRIA3, and ESR1, by PCR amplification. The total number of samples collected for migraine patients was 230, out of which 30 were positive for PCR amplification of the genes GRIA1, GRIA3, and ESR1. Therapeutic potentials of commercial drugs, namely Cyclobenzaprine, Divalproex, Ergotamine, and Sumatriptan, were analyzed in silico through molecular docking. Ergotamine demonstrated the highest binding affinity of [Formula: see text]8.4 kcal/mol for the target molecule and, hence, the highest potential. The bivariate analysis showed that the prevalence of migraine concerning gender and age was significantly correlated ([Formula: see text], [Formula: see text]). It was observed that almost 31.4% of women suffered from headaches daily, 70% weekly, 28.1% monthly, and 23.5% rarely. Comparatively, only 8.3% of males suffered from daily headaches, 34% weekly, 12.8% monthly, and 14.9% rarely. The study shows promising results and encourages future researchers to conduct such a comprehensive epidemiological study on an even larger population to justify a more precise association of risk factors involved in migraine pathophysiology.

Trigger areas nerve decompression for refractory chronic migraine

BACKGROUND

Chronic migraine refractory to medical treatment represents a common debilitating primary neurovascular disorder associated with great disability, high financial costs, reduced rates of productivity and impaired health-related quality of life.

OBJECTIVE

To demonstrate the feasibility of scalp (trigger areas) nerve decompression as a treatment alternative in the management of refractory CM patients METHODS: From January 2005 to January 2020, we retrospectively collected data of 154 patients diagnosed with chronic migraine that underwent trigger site nerve decompression. These trigger areas were divided according the nerve compromise as frontal (supraorbital nerve), temporal (auriculotemporal nerve), occipital (greater occipital nerve). Following extensive clinical evaluation, the surgical treatment was performed after under local anesthesia and required the release of the affected nerve from surrounding connective tissue adhesions, and vascular conflicts.

RESULTS

Of the total amount of patients, 91 (59.09%) patients underwent auriculotemporal nerve decompression, 27 (13.63%) cases supraorbital nerve decompression, 15 (9.74%) patients greater occipital nerve decompression, and the remaining 21 (13.63%) patients had more than one procedure of nerve decompression. At 1-year follow or latest follow-up, 96 (62.2%) patients were considered as cured, 29 cases (18.83%) reported improvement of their symptoms, 21 (13.64%) patients considered only a partial symptomatic remission and 5 (3.25%) patients reported no change or failed surgical treatment.

CONCLUSION

Nerve decompression of trigger site areas (frontal, temporal, occipital) by removal of tissue, muscles and vessels in patients with medically refractory CM is a feasible alternative treatment modality with a high success of up to 80.5.

Genetics, pathophysiology, diagnosis, treatment, management, and prevention of migraine

Migraine is a neurological ailment that is characterized by severe throbbing unilateral headache and associated with nausea, photophobia, phonophobia and vomiting. A full and clear mechanism of the pathogenesis of migraine, though studied extensively, has not been established yet. The current available information indicates an intracranial network activation that culminates in the sensitization of the trigemino-vascular system, release of inflammatory markers, and initiation of meningeal-like inflammatory reaction that is sensed as headache. Genetic factors might play a significant role in deciding an individual's susceptibility to migraine. Twin studies have revealed that a single gene polymorphism can lead to migraine in individuals with a monogenic migraine disorder. In this review, we describe recent advancements in the genetics, pathophysiology, diagnosis, treatment, management, and prevention of migraine. We also discuss the potential roles of genetic and abnormal factors, including some of the metabolic triggering factors that result in migraine attacks. This review will help to accumulate current knowledge about migraine and understanding of its pathophysiology, and provides up-to-date prevention strategies.

Long-Term Efficacy of Occipital Nerve Stimulation for Medically Intractable Cluster Headache

BACKGROUND

Occipital nerve stimulation (ONS) has been proposed to treat refractory chronic cluster headache (rCCH) but its efficacy has only been showed in small short-term series.

OBJECTIVE

To evaluate ONS long-term efficacy in rCCH.

METHODS

We studied 105 patients with rCCH, treated by ONS within a multicenter ONS prospective registry. Efficacy was evaluated by frequency, intensity of pain attacks, quality of life (QoL) EuroQol 5 dimensions (EQ5D), functional (Headache Impact Test-6, Migraine Disability Assessment) and emotional (Hospital Anxiety Depression Scale [HAD]) impacts, and medication consumption.

RESULTS

At last follow-up (mean 43.8 mo), attack frequency was reduced >50% in 69% of the patients. Mean weekly attack frequency decreased from 22.5 at baseline to 9.9 (P < .001) after ONS. Preventive and abortive medications were significantly decreased. Functional impact, anxiety, and QoL significantly improved after ONS. In excellent responders (59% of the patients), attack frequency decreased by 80% and QoL (EQ5D visual analog scale) dramatically improved from 37.8/100 to 73.2/100. When comparing baseline and 1-yr and last follow-up outcomes, efficacy was sustained over time. In multivariable analysis, low preoperative HAD-depression score was correlated to a higher risk of ONS failure. During the follow-up, 67 patients experienced at least one complication, 29 requiring an additional surgery: infection (6%), lead migration (12%) or fracture (4.5%), hardware dysfunction (8.2%), and local pain (20%).

CONCLUSION

Our results showed that long-term efficacy of ONS in CCH was maintained over time. In responders, ONS induced a major reduction of functional and emotional headache-related impacts and a dramatic improvement of QoL. These results obtained in real-life conditions support its use and dissemination in rCCH patients.

Long-Term Outcomes of Occipital Nerve Stimulation for New Daily Persistent Headache With Migrainous Features

OBJECTIVES

New daily persistent headache (NDPH) is a subset of chronic headache where the pain is continuous from onset. Phenotypically it has chronic migraine or chronic tension type features. NDPH is considered to be highly refractory. Occipital nerve stimulation (ONS) has been used for treatment of refractory chronic migraine but there are no specific reports of its use for NDPH with migrainous features.

MATERIALS AND METHODS

Nine patients with NDPH with migrainous features were identified as having had ONS implants between 2007 and 2014 in a specialist unit with experience of using ONS in chronic migraine. Moderate to severe headache days were compared at baseline and follow-up. A positive response was defined as at least 30% reduction in monthly moderate to severe headache days.

RESULTS

Patients had suffered NDPH for a median of 8 years (range 3-16 years) and had failed a median of 11 previous treatments (range 8-15). After a median follow-up of 53 months (range 27-108 months), only a single patient showed a positive response to ONS. At no point did the cohort as a whole show any change in monthly moderate to severe headache days or disability scores.

CONCLUSION

Our experience suggests that ONS is not effective in the treatment of NDPH with migrainous features even in centers with experience in treating chronic migraine with ONS. The difference in response rates of chronic migraine and NDPH with migrainous features supports the concept of a different pathophysiology to the two conditions.

Modulation of mechanosensory vibrissal responses in the trigeminocervical complex by stimulation of the greater occipital nerve in a rat model of trigeminal neuropathic pain

Background

Stimulation of the occipital or trigeminal nerves has been successfully used to treat chronic refractory neurovascular headaches such as migraine or cluster headache, and painful neuropathies. Convergence of trigeminal and occipital sensory afferents in the ‘trigeminocervical complex’ (TCC) from cutaneous, muscular, dural, and visceral sources is a key mechanism for the input-induced central sensitization that may underlie the altered nociception. Both excitatory (glutamatergic) and inhibitory (GABAergic and glycinergic) mechanisms are involved in modulating nociception in the spinal and medullary dorsal horn neurons, but the mechanisms by which nerve stimulation effects occur are unclear. This study was aimed at investigating the acute effects of electrical stimulation of the greater occipital nerve (GON) on the responses of neurons in the TCC to the mechanical stimulation of the vibrissal pad.

Methods

Adult male Wistar rats were used. Neuronal recordings were obtained in laminae II-IV in the TCC in control, sham and infraorbital chronic constriction injury (CCI-IoN) animals. The GON was isolated and electrically stimulated. Responses to the stimulation of vibrissae by brief air pulses were analyzed before and after GON stimulation. In order to understand the role of the neurotransmitters involved, specific receptor blockers of NMDA (AP-5), GABA_A (bicuculline, Bic) and Glycine (strychnine, Str) were applied locally.

Results

GON stimulation produced a facilitation of the response to light facial mechanical stimuli in controls, and an inhibition in CCI-IoN cases. AP-5 reduced responses to GON and vibrissal stimulation and blocked the facilitation of GON on vibrissal responses found in controls. The application of Bic or Str significantly reduced the facilitatory effect of GON stimulation on the response to vibrissal stimulation in controls. However, the opposite effect was found when GABAergic or Glycinergic transmission was prevented in CCI-IoN cases.

Conclusions

GON stimulation modulates the responses of TCC neurons to light mechanical input from the face in opposite directions in controls and under CCI-IoN. This modulation is mediated by GABAergic and Glycinergic mechanisms. These results will help to elucidate the neural mechanisms underlying the effectiveness of nerve stimulation in controlling painful craniofacial disorders, and may be instrumental in identifying new therapeutic targets for their prevention and treatment.

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

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.

A prospective case series of sphenopalatine ganglion pulsed radiofrequency therapy for refractory chronic cluster headache

BACKGROUND AND PURPOSE

The management options for chronic cluster headache (CCH) are limited and a significant proportion of patients become refractory to pharmacological treatments. Pulsed radiofrequency (PRF) of the sphenopalatine ganglion (SPG) may present an efficacious, minimally invasive treatment modality for patients with refractory CCH. We describe the clinical outcomes of 14 patients with refractory CCH treated with PRF of the SPG.

METHODS

Patients with medically refractory CCH who underwent percutaneous SPG-PRF treatment between January 2016 and April 2019 were included in this report. Patients obtaining at least 30% reduction in weekly cluster attacks for at least 3 months were defined as responders. Treatment-related side effects were collected.

RESULTS

A total of 14 patients were included in this report (nine males). At a median follow-up of 6.5 (range 6-13) months post-procedure, eight patients (57.1%) were defined as responders to the treatment. Six patients were non-responders and reported either a reduction in frequency and severity of attacks for <3 months (2/6), no improvement (2/6) or temporary worsening of symptoms (1/6). The majority of patients (63.6%, n = 7/11) treated with >45 V were responders compared with responders treated with 45 V (33.3%, n = 1/3). Five patients (35.7%) experienced post-procedural side effects.

CONCLUSION

This case series suggests that PRF targeting the SPG might offer a safe, minimally invasive and effective treatment for medically refractory CCH. Given the small number of cases and the short follow-up, larger and more robust studies will be needed to confirm our findings.

Signaling Interaction between Facial and Meningeal Inputs of the Trigeminal System Mediates Peripheral Neurostimulation Analgesia in a Rat Model of Migraine

Peripheral neurostimulation within the trigeminal nerve territory has been used for pain alleviation during migraine attacks, but the mechanistic basis of this non-invasive intervention is still poorly understood. In this study, we investigated the therapeutic role of peripheral stimulation of the trigeminal nerve, which provides homosegmental innervation to intracranial structures, by assessing analgesic effects in a nitroglycerin (NTG)-induced rat model of migraine. As a result of neurogenic inflammatory responses in the trigeminal nervous system, plasma protein extravasation was induced in facial skin by applying noxious stimulation to the dura mater. Noxious chemical stimulation of the dura mater led to protein extravasation in facial cutaneous tissues and caused mechanical sensitivity. Trigeminal ganglion (TG) neurons were double-labeled via retrograde tracing to detect bifurcated axons. Extracellular recordings of wide dynamic range (WDR) neurons in the spinal trigeminal nucleus caudalis (Sp5C) demonstrated the convergence and interaction of inputs from facial tissues and the dura mater. Peripheral neurostimulation of homotopic facial tissues represented segmental pain inhibition on cephalic cutaneous allodynia in the migraine model. The results indicated that facial territories and intracranial structures were directly connected with each other through bifurcated double-labeled neurons in the TG and through second-order WDR neurons. Homotopic stimulation at the C-fiber intensity threshold resulted in much stronger inhibition of analgesia than the same intensity of heterotopic stimulation. These results provide novel evidence for the neurological bases through which peripheral neurostimulation may be effective in treating migraine in clinical practice.

Cathodal tDCS Guided by Thermography as Adjunctive Therapy in Chronic Migraine Patients: A Sham-Controlled Pilot Study

Objective: To explore the efficacy of cathodal tDCS applied ipsilateral to the cold patch, as determined by thermographic evaluation, in the treatment of chronic migraine. Background: Transcranial direct current stimulation (tDCS) is a non-invasive and safe technique that modulates the activity of the underlying cerebral cortex. tDCS has been extensively tested as a possible treatment for chronic pain and migraine with controversial results mainly due to the different setting procedure and location of electrodes. Since the presence of a hypothermic patch region detected through thermography has been suggested as a possible support for headache diagnosis, this "cold patch" could considered as possible effective location for tDCS application. Methods: Forty-five patients with chronic migraine were randomized to receive either cathodal (25 patients) or sham tDCS, for 5 consecutive daily sessions plus a recall session after 1 month. Cathodal tDCS was delivered at 1.5 mA for 15 min in each session. Subjects were evaluated before treatment (baseline, T0), and after 10 (T10), 60 (T60), and 120 (T120) days after treatment. The number of attacks, duration of attacks, pain intensity, number of days with headache, and number of analgesics were collected at each time evaluation. Results: Patients in the tDCS group showed a significant improvement compared to the sham group, during the whole study period in the frequency of migraine attacks (tDCS vs. sham: -47.8 ± 50.1% vs. -14.2 ± 16.5%, p = 0.004), number of days with headache (tDCS vs. sham: -42.7 ± 65.4% vs. -11.3 ± 18.0%, p = 0.015), duration of attacks (tDCS vs. sham: -29.1 ± 43.4% vs. -7.5 ± 17.6%, p = 0.016), intensity of the pain during an attack (tDCS vs. sham -31.1 ± 36.9% vs. 8.3 ± 13.5%, p = 0.004), and number of analgesics (tDCS vs. sham -54.3 ± 37.4% vs. -16.0 ± 19.6%, p < 0.0001). Conclusion: Our results suggest that cathodal tDCS is an effective adjuvant technique in migraine provided that an individual correct montage of the electrodes is applied, according to thermographic investigation.

Device review: Pulsante™ sphenopalatine ganglion microstimulator

Cluster headache (CH) is a primary headache disorder. The use of neuromodulation in treatment of CH is well documented. The sphenopalatine ganglion (SPG) has long been a target for management of CH. Intervention at the level of the SPG can interrupt the trigemino-autonomic reflex, which mediates CH pain. The Pulsante system is the only device on the market created for SPG stimulation. The Pulsante device consists of the device body, a lead with six stimulating electrodes placed in the pterygopalatine fossa, and a fixation plate to allow anchoring of the device to the maxilla. Stimulation is administered via a patient-controlled handheld remote control held over the cheek. SPG stimulation is an important treatment option for CH patients.

Neurostimulation methods in the treatment of chronic pain

The goal of this narrative review was to give an up-to-date overview of the peripheral and central neurostimulation methods that can be used to treat chronic pain. Special focus has been given to three pain conditions: neuropathic pain, nociplastic pain and primary headaches. Both non-invasive and invasive techniques are briefly presented together with their pain relief potentials. For non-invasive stimulation techniques, data concerning transcutaneous electrical nerve stimulation (TENS), transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), remote electrical neuromodulation (REN) and vagus nerve stimulation (VNS) are provided. Concerning invasive stimulation techniques, occipital nerve stimulation (ONS), vagus nerve stimulation (VNS), epidural motor cortex stimulation (EMCS), spinal cord stimulation (SCS) and deep brain stimulation (DBS) are presented. The action mode of all these techniques is only partly understood but can be very different from one technique to the other. Patients' selection is still a challenge. Recent consensus-based guidelines for clinical practice are presented when available. The development of closed-loop devices could be of interest in the future, although the clinical benefit over open loop is not proven yet.

Occipital nerve stimulation for non-migrainous chronic headaches: a systematic review protocol

BACKGROUND

Defined as a headache lasting at least 15 days per month, chronic headache is reported by 3% of the general population, and a substantial proportion of them are refractory to current therapies. Occipital nerve stimulation (ONS) is a treatment option, but is still considered as a last resort treatment especially because of its invasive nature and the cost associated. Some reviews reported a limited efficacy of ONS for the treatment of migraines, with a high risk of complications. However, results reporting its efficacy and safety on other headache disorders are unclear. The aim of this review is to assess the efficacy and safety of ONS in regards to non-migrainous chronic headaches.

METHODS

We will conduct a systematic review and meta-analysis of studies evaluating the use of ONS in comparison to sham stimulation or the best available treatment in patients with chronic headache. MEDLINE, CINHAL, EMBASE, PsycINFO, ECRI Institute Library, WIKISTIM, the Cochrane Library databases, and clinical trial registries will be searched for eligible studies. The review will include adult patients diagnosed with chronic headache excluding migraine. Two independent reviewers will process to the screening of studies according to titles, abstracts, and then full texts. The primary outcome is the overall reduction of head pain severity. The secondary outcomes are rates of reduction in the severity of head pain, headache frequency, and duration, use of medication, impairment, quality of life, healthcare utilization, return to work, and adverse events. Extracted data will include patients' and procedure characteristics, details on comparative treatment or sham, and clinical outcomes. The risk of bias of the studies will be also independently assessed using the Cochrane risk of bias tools.

DISCUSSION

This systematic review will allow us to better evaluate the potential role of ONS for the treatment of patients with chronic headache that are refractory to less invasive therapies. It will help to determine the degree of safety of ONS. Moreover, it will help to design and conduct future randomized controlled trials focused on patients who may better respond to such treatment.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019121623.

Emerging treatments for cluster headache: hopes and disappointments

PURPOSE OF REVIEW

Cluster headache stands among the worst debilitating pain conditions. Available treatments for cluster headache have often disabling side effects, are not tolerated, or are ineffective. The management of drug-refractory chronic forms is challenging. New treatments are warranted and reported here.

RECENT FINDINGS

In cluster headache acute treatment, delivery systems like Demand Valve Oxygen or nonrebreather-type masks could enhance the effectiveness of inhaled oxygen therapy. Noninvasive vagus nerve stimulation relieves cluster headache pain at short-term in episodic patients. Sphenopalatine ganglion stimulation combines acute and preventive properties in subsets of patients and is of interest in selected refractory chronic forms. In cluster headache prevention, 'hypothalamic' deep brain stimulation is being refined using slightly different stereotactic coordinates or lower risk methods like endoventricular stimulation. Anti-CGRP monoclonal antibodies provide interesting results in episodic cluster headache, have a good safety profile, but do not appear effective in chronic cluster headache.

SUMMARY

These novel approaches provide additional alternatives to conventional cluster headache management, but results obtained in chronic forms are often disappointing. Research on cluster headache is often hampered by the lack of awareness in the medical world and by the relatively low prevalence of cluster headache compared with migraine. However, common features shared by these two primary headaches could help developing disease-specific therapies.

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.

Potential Application of Optogenetic Stimulation in the Treatment of Pain and Migraine Headache: A Perspective from Animal Studies

Optogenetic manipulation is uniquely useful in unraveling the functional organization of neuronal circuits in the central nervous system by enabling reversible gain- or loss-of-function of discrete populations of neurons within restricted brain regions. This state-of-the-art technology can produce circuit-specific neuromodulation by overexpressing light-sensitive proteins (opsins) in particular cell types of interest. Here, we discuss the principle of optogenetic manipulation and its application in pain research using animal models, and we also discuss how to potentially use optogenetic stimulation in the treatment of migraine headache in the future.

Neuromodulation for Pain Management

Pain is a salient and complex sensory experience with important affective and cognitive dimensions. The current definition of pain relies on subjective reports in both humans and experimental animals. Such definition lacks basic mechanistic insights and can lead to a high degree of variability. Research on biomarkers for pain has previously focused on genetic analysis. However, recent advances in human neuroimaging and research in animal models have begun to show the promise of a circuit-based neural signature for pain. At the treatment level, pharmacological therapy for pain remains limited. Neuromodulation has emerged as a specific form of treatment without the systemic side effects of pharmacotherapies. In this review, we will discuss some of the current neuromodulatory modalities for pain, research on newer targets, as well as emerging possibility for an integrated brain-computer interface approach for pain management.

The greater occipital nerve and its spinal and brainstem afferent projections: A stereological and tract-tracing study in the rat

The neuromodulation of the greater occipital nerve (GON) has proved effective to treat chronic refractory neurovascular headaches, in particular migraine and cluster headache. Moreover, animal studies have shown convergence of cervical and trigeminal afferents on the same territories of the upper cervical and lower medullary dorsal horn (DH), the so-called trigeminocervical complex (TCC), and recent studies in rat models of migraine and craniofacial neuropathy have shown that GON block or stimulation alter nociceptive processing in TCC. The present study examines in detail the anatomy of GON and its central projections in the rat applying different tracers to the nerve and quantifying its ultrastructure, the ganglion neurons subserving GON, and their innervation territories in the spinal cord and brainstem. With considerable intersubject variability in size, GON contains on average 900 myelinated and 3,300 unmyelinated axons, more than 90% of which emerge from C₂ ganglion neurons. Unmyelinated afferents from GON innervates exclusively laminae I-II of the lateral DH, mostly extending along segments C_2-3 . Myelinated fibers distribute mainly in laminae I and III-V of the lateral DH between C₁ and C₆ and, with different terminal patterns, in medial parts of the DH at upper cervical segments, and ventrolateral rostral cuneate, paratrigeminal, and marginal part of the spinal caudal and interpolar nuclei. Sparse projections also appear in other locations nearby. These findings will help to better understand the bases of sensory convergence on spinomedullary systems, a critical pathophysiological factor for pain referral and spread in severe painful craniofacial disorders.

Hemicrania Continua: a Clinical Perspective on Diagnosis and Management

PURPOSE OF REVIEW

Hemicrania Continua (HC) is a daily and persistent form of headache that is characterized by side-locked pain which is continuous, varies in severity and can be associated with conjunctival injection, lacrimation, nasal congestion, rhinorrhea, eyelid edema, forehead or facial sweating and miosis and/or ptosis.

RECENT FINDINGS

Functional imaging studies have shown activation of subcortical structures such as the posterior hypothalamus and dorsal rostral pons, which are known to disinhibit the trigeminal autonomic reflex, a reflex responsible for autonomic outflow through trigeminal efferents. A similar pathway activation is seen in other Trigeminal autonomic cephalalgias (TAC) which solidifies HC as a TAC. While we also discuss promising treatments in our review, more evidence is needed before making them a standard of therapy for HC. This article aims to review the recent research on the diagnosis and clinical management of this potentially underdiagnosed primary headache disorder.

Primary Headaches

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

Migraine and cluster headache - the common link

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

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.

Cluster headache: new targets and options for treatment

Cluster headache is a severe headache disorder with considerable impact on quality of life. The pathophysiology of the disease remains poorly understood. With few specific targets for treatment, current guidelines mainly include off-label treatment with medication. However, new targets for possible treatment options are emerging. Calcitonin gene-related peptide (CGRP)-targeted medication could become the first (cluster) headache-specific treatment option. Other exciting new treatment options include invasive and non-invasive neuromodulation techniques. Here, we provide a short overview of new targets and treatment options that are being investigated for cluster headache.

Cluster headache: present and future therapy

Cluster headache is characterized by severe, unilateral headache attacks of orbital, supraorbital or temporal pain lasting 15-180 min accompanied by ipsilateral lacrimation, rhinorrhea and other cranial autonomic manifestations. Cluster headache attacks need fast-acting abortive agents because the pain peaks very quickly; sumatriptan injection is the gold standard acute treatment. First-line preventative drugs include verapamil and carbolithium. Other drugs demonstrated effective in open trials include topiramate, valproic acid, gabapentin and others. Steroids are very effective; local injection in the occipital area is also effective but its prolonged use needs caution. Monoclonal antibodies against calcitonin gene-related peptide are under investigation as prophylactic agents in both episodic and chronic cluster headache. A number of neurostimulation procedures including occipital nerve stimulation, vagus nerve stimulation, sphenopalatine ganglion stimulation and the more invasive hypothalamic stimulation are employed in chronic intractable cluster headache.

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.

Cluster headache

Cluster headache is an excruciating, strictly one-sided pain syndrome with attacks that last between 15 minutes and 180 minutes and that are accompanied by marked ipsilateral cranial autonomic symptoms, such as lacrimation and conjunctival injection. The pain is so severe that female patients describe each attack as worse than childbirth. The past decade has seen remarkable progress in the understanding of the pathophysiological background of cluster headache and has implicated the brain, particularly the hypothalamus, as the generator of both the pain and the autonomic symptoms. Anatomical connections between the hypothalamus and the trigeminovascular system, as well as the parasympathetic nervous system, have also been implicated in cluster headache pathophysiology. The diagnosis of cluster headache involves excluding other primary headaches and secondary headaches and is based primarily on the patient's symptoms. Remarkable progress has been achieved in developing effective treatment options for single cluster attacks and in developing preventive measures, which include pharmacological therapies and neuromodulation.

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

Predictors of response to occipital nerve stimulation in refractory chronic headache

Background

Occipital nerve stimulation is a promising treatment for refractory chronic headache disorders, but is invasive and costly. Identifying predictors of response would be useful in selecting patients. We present the results of an open-label prospective cohort study of 100 patients (35 chronic migraine, 33 chronic cluster headache, 20 short-lasting unilateral neuralgiform headache attacks and 12 hemicrania continua) undergoing occipital nerve stimulation, using a multivariate binary regression analysis to identify predictors of response.

Results

Response rate of the cohort was 48%. Multivariate analysis showed short lasting unilateral neuralgiform headache attacks (OR 6.71; 95% CI 1.49–30.05; p = 0.013) and prior response to greater occipital nerve block (OR 4.22; 95% CI 1.35–13.21; p = 0.013) were associated with increased likelihood of response. Presence of occipital pain (OR 0.27; 95% CI 0.09–0.76; p = 0.014) and the presence of severe anxiety and/or depression (as measured on hospital anxiety and depression score) at time of implantation (OR 0.32; 95% CI 0.11–0.91; p = 0.032) were associated with reduced likelihood of response.

Conclusion

Possible clinical predictors of response to occipital nerve stimulation for refractory chronic headaches have been identified. Our data shows that those with short-lasting unilateral neuralgiform headache attacks respond better than those with chronic migraine, and that a prior response to greater occipital nerve block is associated with positive outcomes. This study suggests that the presence of occipital pain and severe mood disorder at time of implant are both associated with poor outcomes to occipital nerve stimulation.

Effect of percutaneous electrical nerve stimulation for the treatment of migraine

BACKGROUND

This study aimed to assess the effectiveness and safety of percutaneous electrical nerve stimulation (PENS) in migraine treatment.

METHODS

Sixty-two patients with at least 2 migration attacks each month were recruited and randomly divided into a verum PENS group and a sham PENS group in a ratio of 1:1. All patients received verum or sham PENS 30 minutes daily, 5 times weekly for 12 weeks. The primary outcomes were change in monthly migraine days (MMD) and the 50% responder rate (RR). Secondary outcomes were evaluated using the monthly migraine attacks (MMA), monthly headache days (MHD), and monthly acute antimigraine drug intake (MAADI). All outcome measurements were performed at treatment initiation to establish a baseline and again after 12 weeks of treatment.

RESULTS

At the end of the 12 weeks, the group receiving verum PENS exhibited statistically significant decrease in the mean MMD compared with the group receiving sham PENS intervention (P < .05). Additionally, the 50% RR was significantly higher in the verum PENS group than that in the sham PENS group (P < .05). Furthermore, the MMA, MHD, and MAADI were also significantly lower in the verum PENS group that those in the sham PENS group (P < .05).

CONCLUSION

The results of this study demonstrated that verum PENS is more effective and safe than Sham PENS for the treatment of migraine.

Long-term follow up of intractable chronic short lasting unilateral neuralgiform headache disorders treated with occipital nerve stimulation

Background Occipital nerve stimulation is a potential treatment option for medically intractable short-lasting unilateral neuralgiform headache attacks. We present long-term outcomes in 31 patients with short-lasting unilateral neuralgiform headache attacks treated with occipital nerve stimulation in an uncontrolled open-label prospective study. Methods Thirty-one patients with intractable short-lasting unilateral neuralgiform headache attacks were treated with bilateral occipital nerve stimulation from 2007 to 2015. Data on attack characteristics, quality of life, disability and adverse events were collected. Primary endpoint was change in mean daily attack frequency at final follow-up. Results At a mean follow-up of 44.9 months (range 13-89) there was a 69% improvement in attack frequency with a response rate (defined as at least a 50% improvement in daily attack frequency) of 77%. Attack severity reduced by 4.7 points on the verbal rating scale and attack duration by a mean of 64%. Improvements were seen in headache-related disability and depression. Adverse event rates were favorable, with no electrode migration or erosion reported. Conclusion Occipital nerve stimulation appears to offer a safe and efficacious treatment for refractory short-lasting unilateral neuralgiform headache attacks with significant improvements sustained in the long term. The procedure has a low adverse event rate when conducted in highly specialised units.

The pathophysiology of episodic cluster headache: Insights from recent neuroimaging research

Background

Cluster headache is a disorder characterized by intermittent, severe unilateral head pain accompanied by cranial autonomic symptoms. Most cases of CH are episodic, manifesting as “in-bout” periods of frequent headache separated by month-to-year-long “out-of-bout” periods of remission. Previous imaging studies have implicated the hypothalamus and pain matrix in the pathogenesis of episodic CH. However, the pathophysiology driving the transition between in- and out-of-bout periods remains unclear.

Methods

The present study provides a narrative review of previous neuroimaging studies on the pathophysiology of episodic CH, addressing alterations in brain structures, metabolism, and structural and functional connectivity occurring between bout periods.

Results

Although the precise brain structures responsible for episodic CH are unknown, major roles are indicated for the posterior hypothalamus (especially in acute attacks), the pain neuromatrix with an emphasis on central descending pain modulation, and non-traditional pain processing networks including the occipital, cerebellar, and salience networks. These areas are potentially related to dynamic transitioning between in- and out-of-bout periods.

Conclusion

Recent progress in magnetic resonance imaging of episodic CH has provided additional insights into dynamic bout-associated structural and functional connectivity changes in the brain, especially in non-traditional pain processing network areas. These areas warrant future investigations as targets for neuromodulation in patients with CH.

Functional Changes of the Perigenual Part of the Anterior Cingulate Cortex after External Trigeminal Neurostimulation in Migraine Patients

Objective

To explore the functional reorganization of the pain processing network during trigeminal heat stimulation (THS) after 60 days of external trigeminal neurostimulation (eTNS) in migraine without aura (MwoA) patients between attacks.

Methods

Using whole-brain BOLD-fMRI, functional response to THS at two different intensities (41 and 51°C) was investigated interictally in 16 adults MwoA patients before and after eTNS with the Cefaly^® device. We calculated the percentage of patients having at least a 50% reduction of monthly migraine attacks and migraine days between baseline and the last month of eTNS. Secondary analyses evaluated associations between BOLD signal changes and clinical features of migraine.

Results

Before eTNS treatment, there was no difference in BOLD response between MwoA patients and healthy controls (HC) during low-innocuous THS at 41°C, whereas the perigenual part of the right anterior cingulate cortex (ACC) revealed a greater BOLD response to noxious THS at 51°C in MwoA patients when compared to HC. The same area demonstrated a significant reduced BOLD response induced by the noxious THS in MwoA patients after eTNS (p = 0.008). Correlation analyses showed a significant positive correlation between ACC BOLD response to noxious THS before eTNS treatment and the decrease of ACC BOLD response to noxious THS after eTNS. Moreover, a significant negative correlation in the migraine group after eTNS treatment between ACC functional activity changes and both the perceived pain ratings during noxious THS and pre-treatment migraine attack frequency has been found.

Conclusion

Our findings suggest that eTNS treatment with the Cefaly^® device induces a functional antinociceptive modulation in the ACC that is involved in the mechanisms underlying its preventive anti-migraine efficacy. Nevertheless, further observations to confirm whether the observed fMRI effects of eTNS are both related to clinical improvement and specific to antinociceptive modulation in migraine patients are mandatory.

External Trigeminal Nerve Stimulation for the Acute Treatment of Migraine: Open-Label Trial on Safety and Efficacy

OBJECTIVE

The aim of the current study is to assess the safety and efficacy of external trigeminal nerve stimulation (e-TNS) via a transcutaneous supraorbital stimulator as an acute treatment for migraine attacks.

MATERIALS AND METHODS

This was a prospective, open-labeled clinical trial conducted at the Columbia University Headache Center (NY, USA). Thirty patients who were experiencing an acute migraine attack with or without aura were treated with a one-hour session of e-TNS (CEFALY Technology) at the clinic. Pain intensity was scored using a visual analogue scale (VAS) before the treatment, after the one-hour treatment session, and at two hours after treatment initiation. Rescue migraine medication intake was recorded at 2 and 24 hours.

RESULTS

Thirty patients were included in the intention-to-treat analysis. Mean pain intensity was significantly reduced by 57.1% after the one-hour e-TNS treatment (-3.22 ± 2.40; p < 0.001) and by 52.8% at two hours (-2.98 ± 2.31; p < 0.001). No patients took rescue medication within the two-hour observation phase. Within the 24-hour follow-up, 34.6% of patients used a rescue medication. No adverse events or subjective complaints were reported.

CONCLUSIONS

The findings from this open-labeled study suggest that transcutaneous supraorbital neurostimulation may be a safe and effective acute treatment for migraine attacks, and merits further study with a double-blind, randomized, sham-controlled trial.