Occipital Nerve Blockade in Chronic Cluster Headache Patients and Functional Connectivity Between Trigeminal and Occipital Nerves

Review of craniofacial pain syndromes involving the greater occipital nerve: relevant anatomy, clinical findings, and interventional management

Craniofacial pain syndromes exhibit a high prevalence in the general population, with a subset of patients developing chronic pain that significantly impacts their quality of life and results in substantial disabilities. Anatomical and functional assessments of the greater occipital nerve (GON) have unveiled its implication in numerous craniofacial pain syndromes, notably through the trigeminal-cervical convergence complex. The pathophysiological involvement of the greater occipital nerve in craniofacial pain syndromes, coupled with its accessibility, designates it as the primary target for various interventional procedures in managing craniofacial pain syndromes. This educational review aims to describe multiple craniofacial pain syndromes, elucidate the role of GON in their pathophysiology, detail the relevant anatomy of the greater occipital nerve (including specific intervention sites), highlight the role of imaging in diagnosing craniofacial pain syndromes, and discuss various interventional procedures such as nerve infiltration, ablation, neuromodulation techniques, and surgeries. Imaging is essential in managing these patients, whether for diagnostic or therapeutic purposes. The utilization of image guidance has demonstrated an enhancement in reproducibility, as well as technical and clinical outcomes of interventional procedures. Studies have shown that interventional management of craniofacial pain is effective in treating occipital neuralgia, cervicogenic headaches, cluster headaches, trigeminal neuralgia, and chronic migraines, with a reported efficacy of 60-90% over a duration of 1-9 months. Repeated infiltrations, neuromodulation, or ablation may prove effective in selected cases. Therefore, reassessment of treatment response and efficacy during follow-up is imperative to guide further management and explore alternative treatment options. Optimal utilization of imaging, interventional techniques, and a multidisciplinary team, including radiologists, will ensure maximum benefit for these patients.

Effectiveness and safety profile of greater occipital nerve blockade in cluster headache: a systematic review

BACKGROUND

Greater occipital nerve (GON) blockade is a short-term preventive therapy for cluster headache (CH). We conducted a systematic review to evaluate the effectiveness and safety of GON blockade in patients with CH.

METHODS

On 23 October 2020, we searched MEDLINE, Embase, Embase Classic, PsycINFO, CINAHL, CENTRAL and Web of Science databases from their inception date. Studies included participants with a CH diagnosis who received corticosteroid and local anaesthetic suboccipital region injections. Outcomes were change in the frequency/severity/duration of attacks; proportion of participants responding to treatment, time to attack freedom from an attack, change in attack bout length and/or the presence of adverse effects after GON blockade. Risk of bias was assessed with the Cochrane Risk of Bias V.2.0 (RoB2)/Risk of Bias in Non-randomized Studies - of Interventions (ROBINS- I) tools and a specific tool for case reports/series.

RESULTS

Two RCTs, eight prospective and eight retrospective studies, and four case reports were included in the narrative synthesis. Every effectiveness study found a significant response in one or more of frequency/severity/duration of individual attacks or proportion of patients responding to treatment (47.8%-100.0%). There were five instances of potentially irreversible adverse effects. A higher injectate volume and use of concurrent prophylaxis may be associated with an increased likelihood of response. Methylprednisolone may have the best safety profile of available corticosteroids.

DISCUSSION

GON blockade is safe and effective for CH prevention. Higher injectate volumes may improve likelihood of response, and the likelihood of serious adverse events may be reduced by using methylprednisolone.

PROSPERO REGISTRATION NUMBER

CRD42020208435.

Transient side shift of cluster headache attacks after unilateral greater occipital nerve injection

Attacks of cluster headache (CH) are usually side-locked in most, but not all, patients. In a few patients, the side may alternate between or, rarely, within cluster episodes. We observed seven cases in whom the side of CH attacks temporarily shifted immediately or shortly after unilateral injection of the greater occipital nerve (GON) with corticosteroids. In five patients with previously side-locked CH attacks and in two patients with previously side-alternating CH attacks, a side shift for several weeks occurred immediately (N = 6) or shortly (N = 1) after GON injection. We concluded that unilateral GON injections might cause a transient side shift of CH attacks through inhibition of the ipsilateral hypothalamic attack generator causing relative overactivity of the contralateral side. The potential benefit of bilateral GON injection in patients who experienced a side shift after unilateral injection should be formally investigated.

Greater occipital nerve block modulates nociceptive signals within the trigeminocervical complex

INTRODUCTION

The pharmacological block of the greater occipital nerve has been proven effective in numerous headache and facial pain syndromes. This clinical effect supports the hypothesis of a strong functional interaction between the occipital and trigeminal nerves which has been proposed in neurophysiological in vivo experiments in rodents. Although it is likely that the interaction has to occur in the central nervous system, the exact site and the mechanisms of the interaction remain largely unknown.

METHODS

Focusing on these questions we investigated in a double-blind, placebo-controlled, randomised study the influence of an occipital nerve block with lidocaine 1% on neuronal activation in the trigeminocervical complex using high-resolution functional magnetic resonance on a 3T scanner. In order to investigate potential clinical effects on the trigeminal nerve, we further performed quantitative sensory testing and analysed a potential shift in thermal detection and pain thresholds.

RESULTS

The pharmacological block of the greater occipital nerve induced an occipital anaesthesia ipsilateral to the block. Functional imaging revealed that the occipital injection of lidocaine but not placebo significantly reduced nociceptive trigeminal activation.

CONCLUSIONS

These data suggest that the functional inhibition of the occipital nerve block on trigeminal nociceptive activity is likely to occur at the C2 level where the occipital nerve enters the trigeminocervical complex and converges on the same central nuclei before the signal crosses the midline at that level and is then transmitted to higher processing centres.

Regional cerebral blood flow as predictor of response to occipital nerve block in cluster headache

Background

Cluster headache is an excruciating disorder with no cure. Greater occipital nerve blockades can transiently suppress attacks in approximately 50% of patients, however, its mechanism of action remains uncertain, and there are no reliable predictors of treatment response. To address this, we investigated the effect of occipital nerve blockade on regional cerebral blood flow (rCBF), an index of brain activity, and differences between treatment responders and non-responders. Finally, we compared baseline perfusion maps from patients to a matched group of healthy controls.

Methods

21 male, treatment-naive patients were recruited while in a cluster headache bout. During a pain-free phase between headaches, patients underwent pseudo-continuous arterial spin labelled MRI assessments to provide quantitative indices of rCBF. MRIs were performed prior to and 7-to-21 days following treatment. Patients also recorded the frequency of their headache attacks in a daily paper diary. Neuropsychological assessment including anxiety, depression and quality of life measures was performed in a first, scanning free session for each patient.

Results

Following treatment, patients demonstrated relative rCBF reductions in posterior temporal gyrus, cerebellum and caudate, and rCBF increases in occipital cortex. Responders demonstrated relative rCBF increases, compared to non-responders, in medial prefrontal cortex and lateral occipital cortex at baseline, but relative reductions in cingulate and middle temporal cortices. rCBF was increased in patients compared to healthy controls in cerebellum and hippocampus, but reduced in orbitofrontal cortex, insula and middle temporal gyrus.

Conclusions

We provide new mechanistic insights regarding the aetiology of cluster headache, the mechanisms of action of occipital nerve blockades and potential predictors of treatment response. Future investigation should determine whether observed effects are reproducible and extend to other headache disorders.

Role of Greater Occipital Nerve Block in Headache Disorders: A Narrative Review

Background

The proximity of sensory neurons in the upper cervical spinal cord to the trigeminal nucleus caudalis (TNC) neurons and the convergence of sensory input to TNC neurons from both cervical and trigeminal fibers underscore the rationale of using greater occipital nerve block (GON-block) for acute and preventive treatment in various headache disorders.

Objective

The aim of this study was to critically review the existing literature regarding the safety and efficacy of GON-block in various headache disorders.

Methods

We searched the eligible studies in English by searching in PubMed till December 31, 2020 for randomized controlled trials (RCTs), observational studies, open-label studies, case series, and case reports on the efficacy and the safety of GON-block for the treatment of headache disorders using the keywords "greater occipital nerve block", "headache" and "treatment". Studies using combination of GON-block and other peripheral nerve blocks (PNBs) and C2/C3 blocks were excluded.

Results

Seventy-two eligible studies were reviewed. Based on RCTs and open-label studies, good evidence of the efficacy of GON-block was found for migraine, cluster headache (CH), post-dural puncture headache (PDPH), cervicogenic headache (CGH), and occipital neuralgia (ON). The analgesic effect of GON-block outlasted its anesthetic effect by days to weeks. Evidence for acute and short-term (transitional) treatment was more robust than for long-term prevention. GON-block was found to be safe and the treatment-emergent adverse effects (TEAEs) were generally mild and transient.

Conclusion

GON-block is a useful modality of treatment in various headache disorders because of many attractive features such as its early effect in reducing the severity of pain, sustained effect following a single injection, easy technique, minimum invasiveness, minimum TEAE, no drug-to-drug interactions, and negligible cost.

Cluster Headache: What's New?

Background

Cluster headache is a highly disabling primary headache disorder which is widely described as the most painful condition a human can experience.

Aim

To provide an overview of the clinical characteristics, epidemiology, risk factors, differential diagnosis, pathophysiology and treatment options of cluster headache, with a focus on recent developments in the field.

Methods

Structured review of the literature on cluster headache.

Results

Cluster headache affects approximately one in 1000 of the population. It is characterised by attacks of severe unilateral head pain associated with ipsilateral cranial autonomic symptoms, and the tendency for attacks to occur with circadian and circannual periodicity. The pathophysiology of cluster headache and other primary headache disorders has recently become better understood and is thought to involve the hypothalamus and trigeminovascular system. There is good quality evidence for acute treatment of attacks with parenteral triptans and high flow oxygen; preventive treatment with verapamil; and transitional treatment with oral corticosteroids or greater occipital nerve injection. New pharmacological and neuromodulation therapies have recently been developed.

Conclusion

Cluster headache causes distinctive symptoms, which once they are recognised can usually be managed with a variety of established treatments. Recent pathophysiological understanding has led to the development of newer pharmacological and neuromodulation therapies, which may soon become established in clinical practice.

Drug profile: galcanezumab for prevention of cluster headache

Introduction: Cluster headache [CH] is a severely disabling trigeminal autonomic cephalalgia [TAC]. Approximately 1 in 1,000 adults are affected by CH. Calcitonin gene-related peptide [CGRP] is an important mediator in the pathophysiology of CH. Galcanezumab is a monoclonal antibody with an affinity for the CGRP peptide, FDA approved for the prevention of episodic CH. Areas covered: Search words queried were 'cluster headache,' 'cluster headache, and CGRP,' 'cluster headache, and galcanezumab.' Over 99 articles in Pubmed and prescribing information for galcanezumab were reviewed. Some of the data pertaining to CH trials with fremanezumab were reviewed using clinical trials.org. Expert opinion: Galcanezumab has shown benefit in decreasing the weekly frequency of CH attacks across week 1 through week 3 in patients with CH; 8.7 attacks in the galcanezumab group, as compared with 5.2 in the placebo group (95% confidence interval, 0.2 to 6.7; P = 0.04). It has a favorable risk-benefit ratio. The prevention of CH with CGRP inhibition represents a novel advance for a condition with a significant unmet need. The negative trial results of galcanezumab for chronic cluster headache [CCH] may be due to the refractory nature and sheds light on the critical need to investigate the underlying biology and therapeutic options.

Muscle endurance training of the neck triggers migraine attacks

BACKGROUND

Most migraine patients report neck pain as part of their migraine symptomatology, but it is unknown whether triggering neck pain would induce migraine attacks. Our aim was to assess the occurrence of headache and/or neck pain after an endurance test of the neck muscles among migraineurs and controls.

METHODS

Sixty-five patients with migraine and 32 headache-free participants underwent a manual examination of the cervical spine by an assessor blinded towards the diagnosis and were sub-classified according to the appearance or absence of neck pain. Subsequently, the endurance of the neck flexors and extensors was tested three times, in a random order. The maximum sustained duration was recorded and the test was terminated when the subject was unable to maintain the position or reported pain. On the day after the assessment, participants were asked to report the potential occurrence of headache or neck symptoms.

RESULTS

None of the controls reported headache after assessment, while migraine-like headache was reported by 42% of the patients with migraine (p < 0.001) after 15.8 h (SD: 10.0). Neck pain was more prevalent in migraineurs compared to controls (45% vs. 16%, p = 0.006). When considering the neck pain subtype, there were no differences among the three profiles regarding neck pain but participants with referred pain to the head reported a migraine attack more often (45%, p = 0.03).

CONCLUSION

Patients with migraine are more likely to report neck pain and migraine attacks following a neck muscle endurance test. Participants with neck pain referred to the head during manual examination had a greater prevalence of migraine attacks than those without or with only local pain.

Efficacy and safety of greater occipital nerve block for the treatment of cluster headache: a systematic review and meta-analysis

INTRODUCTION

The treatment of cluster headache (CH) is challenging in view of the few evidence-based treatments. The authors aim to summarize the evidence of efficacy and safety of greater occipital nerve blocks (GONBs) in CH.

AREAS COVERED

The authors included papers indexed in PubMed and Web of Science from the beginning of indexing to 5 May 2020. They included both observational and randomized studies referring to patients with episodic and/or chronic CH. The authors identified 12 studies on 365 patients. Five studies (two randomized controlled trials) could be included in the meta-analyses. The pooled proportion of pain-free subjects at 1 month was 50% (95% CI 24-76%) with considerable heterogeneity (I² = 88%; P < 0.01). The pooled relative risk ratio of pain freedom at 1 month in active versus control groups in the two included randomized controlled trials was 4.86 (95% CI, 1.35-17.55) without statistical heterogeneity (I² = 0%; P = 0.39). Three studies showed decreased attack intensity, frequency, and duration after GONBs. The studies reported mild and transient adverse events.

EXPERT OPINION

Despite several limitations and considerable heterogeneity, the available data support the efficacy and safety of GONBs for the treatment of CH. Further large randomized trials are needed to confirm efficacy and establish optimal treatment protocols.

Cluster Headache in Kuwait: A Hospital-Based Study

Background: Cluster headache (CH) is a relatively uncommon primary headache disorder. Few studies in our region described CH. We aimed to study demographics, clinical characteristics and treatment modalities of CH patients referred to Headache Clinic in Kuwait. Materials and Methods: This cross-sectional study included all CH patients who are referred to headache clinic. The diagnosis of CH based on the CH diagnostic criteria of the Headache Classification Committee of the IHS, 3rd edition (beta version) (ICHD-3-beta). The demographics, clinical characteristics and treatment modalities of CH patients were recorded. Results: Forty six patients were diagnosed with CH which constituted 1.7% of all headache patients and 0.1% of all visits to Neurology clinic. Male:Female ratio was 15.3:1. Mean age was 40.1 ± 10.7 years and mean age at onset was 29 years (20-49). Family history was positive in 6.5%. Smoking was seen in 63.0% of patients while 6.5 % reported alcohol intake. CH was episodic in 84.4% and chronic in 15.2%. Seasonal predilection was seen in all patients; the most frequent season was Autumn 47.8%. The mean duration of the cluster bouts was 6 weeks (2-12 weeks). The mean duration of the attack was 60 min (15-180 min). Number of attacks per day ranged from 2 to 10 attacks with a mean of 5 attacks/day. The median of attack severity by Visual Analog Scale (VAS) was 8.5 (7-10). The time taken to diagnose the patients ranged from <1 year to 12 years with a mean of 4 years. Chronic CH have a statically significant relation with smoking (P = 0.036), older age (P = 0.027), and longer time taken to diagnosis (P = 0.026) compared to episodic CH. Conclusion: Our results reported that there is higher proportion of males compared to females and less positive family history. Smoking was a significant risk factor for chronicity in addition to advanced age, higher age at disease onset and a longer time taken till diagnosis.

Regional anesthesia in pain management

PURPOSE OF REVIEW

The study focuses on neural blocks with local anesthetics in postoperative and chronic pain. It is prompted by the recent publication of several systematic reviews and guidelines.

RECENT FINDINGS

For postoperative pain, the current evidence supports infusions of local anesthetics at the surgical site, continuous peripheral nerve blocks, and neuraxial analgesia for major thoracic and abdominal procedures. Ultrasound guidance can improve the performance of the blocks and different patient outcomes, although the incidence of peripheral nerve damage is not decreased. For chronic pain, the best available evidence is on nerve blocks for the diagnosis of facet joint pain. Further research is needed to validate diagnostic nerve blocks for other indications. Therapeutic blocks with only local anesthetics (greater occipital nerve and sphenopalatine ganglion) are effective in headache. A possible mechanism is modulation of central nociceptive pathways. Therapeutic nerve blocks for other indications are mostly supported by retrospective studies and case series.

SUMMARY

Recent literature strongly supports the use of regional anesthesia for postoperative pain, whereby infusions at peripheral nerves and surgical site are gaining increasing importance. Local anesthetic blocks are valid for the diagnosis of facet joint pain and effective in treating headache. There is a need for further research in diagnostic and therapeutic blocks for chronic pain.

Diagnosis, pathophysiology, and management of cluster headache

Cluster headache is a trigeminal autonomic cephalalgia characterised by extremely painful, strictly unilateral, short-lasting headache attacks accompanied by ipsilateral autonomic symptoms or the sense of restlessness and agitation, or both. The severity of the disorder has major effects on the patient's quality of life and, in some cases, might lead to suicidal ideation. Cluster headache is now thought to involve a synchronised abnormal activity in the hypothalamus, the trigeminovascular system, and the autonomic nervous system. The hypothalamus appears to play a fundamental role in the generation of a permissive state that allows the initiation of an episode, whereas the attacks are likely to require the involvement of the peripheral nervous system. Triptans are the most effective drugs to treat an acute cluster headache attack. Monoclonal antibodies against calcitonin gene-related peptide, a crucial neurotransmitter of the trigeminal system, are under investigation for the preventive treatment of cluster headache. These studies will increase our understanding of the disorder and perhaps reveal other therapeutic targets.

Invasive pericranial nerve interventions

Background

In many patients suffering from primary headaches, the available pharmacological and behavioural treatments are not satisfactory. This is a review of (minimally) invasive interventions targeting pericranial nerves that could be effective in refractory patients.

Methods

The interventions we will cover have in common pericranial nerves as targets, but are distinct according to their rationale, modality and invasiveness. They range from nerve blocks/infiltrations to the percutaneous implantation of neurostimulators and surgical decompression procedures. We have critically analysed the published data (PubMed) on their effectiveness and tolerability.

Results and conclusions

There is clear evidence for a preventative effect of suboccipital injections of local anaesthetics and/or steroids in cluster headache, while evidence for such an effect is weak in migraine. Percutaneous occipital nerve stimulation (ONS) provides significant long-term relief in more than half of drug-resistant chronic cluster headache patients, but no sham-controlled trial has tested this. The evidence that ONS has lasting beneficial effects in chronic migraine is at best equivocal. Suboccipital infiltrations are quasi-devoid of side effects, while ONS is endowed with numerous, though reversible, adverse events. Claims that surgical decompression of multiple pericranial nerves is effective in migraine are not substantiated by large, rigorous, randomized and sham-controlled trials.

ATP-sensitive muscle afferents activate spinal trigeminal neurons with meningeal afferent input in rat - pathophysiological implications for tension-type headache

BACKGROUND

Tension-type headache and other primary headaches may be triggered or aggravated by disorders of pericranial muscles, which is possibly due to convergent or collateral afferent input from meningeal and muscular receptive areas. In rodent models high extracellular concentrations of ATP caused muscle nociception and central sensitization of second order neurons. In a rat model of meningeal nociception we asked if spinal trigeminal activity induced by ATP can be modulated by local anaesthesia of distinct muscles.

METHODS

Ongoing activity was recorded from spinal trigeminal neurons with afferent input from the cranial dura mater, the temporal muscle and neck muscles. The stable ATP analogue α,β-methylene adenosine 5'-triphosphate (α,β-meATP, 10 mM) was injected into the ipsilateral temporal muscle, 30 min later followed by injection of local anaesthetics (lidocaine, 2 %) into the ipsilateral neck muscles and/or the temporal muscle.

RESULTS

Injection of α,β-meATP into the temporal muscle caused progressive increase in ongoing activity of most of the spinal trigeminal neurons within 30 min. Injection of lidocaine into the neck muscles and/or the temporal muscle reduced this activation to previous levels within 10 min.

CONCLUSIONS

Distinct spinal trigeminal neurons processing meningeal nociceptive information are under the control of convergent afferent input from several pericranial muscles. Blockade of at least one of these inputs can normalize central trigeminal activity. This may explain why therapeutic manipulations of head muscles can be beneficial in primary headaches.

Efficacy and safety of a single occipital nerve blockade in episodic and chronic cluster headache: A prospective observational study

Background Treatment options for cluster headache (CH) include acute, transitional and prophylactic strategies. We assessed the efficacy and safety of a single occipital nerve block (ONB) in patients with episodic (eCH) and chronic CH (cCH). Methods In this prospective, observational study 101 CH were treated with a single ONB using triamcinolone 10 mg and bupivacaine. Attack frequency, pain intensity and side effects were assessed at days 1 and 7 after ONB and thereafter weekly for 60 days until recurrence of attacks. Results Baseline mean daily attack frequency was 2.9 ± 2.5 (eCH) and 3.3 ± 2.9 (cCH), which was reduced to 0.7 ± 1.2 (eCH) and 1.1 ± 1.4 (cCH) after one day ( p = 0.08 for group difference) and to 1.1 ± 1.6 (eCH) and 1.9 ± 2.3 (cCH) after seven days ( p = 0.01 for group difference). In patients with eCH the pain-free period lasted longer compared to cCH ( p = 0.004). There was no association between the presence of local anesthesia and treatment response ( p = 0.88). No serious adverse events occurred. Conclusion ONB is an easy, safe and effective transitional treatment option in case of insufficient response of CH to treatment both in patients with eCH and cCH. Patients with eCH have a better and more sustainable treatment response.

Primary Headache Disorders: Focus on Migraine

Migraine is the most common disabling headache disorder.Most patients with disabling tension-type headache are likely to have migraine and accordingly respond to treatments efficacious in migraine.Individuals are genetically predisposed to experiencing recurrent migraine.Evidence supports migraine to be a primarily neural and not vascular mediated disorder.1-2% of the population have chronic daily headache associated with acute-relief medication overuse; the majority are migraineurs.The presence of acute-relief medication overuse renders preventative medication less adequately efficacious.

Neural Plasticity in Common Forms of Chronic Headaches

Headaches are universal experiences and among the most common disorders. While headache may be physiological in the acute setting, it can become a pathological and persistent condition. The mechanisms underlying the transition from episodic to chronic pain have been the subject of intense study. Using physiological and imaging methods, researchers have identified a number of different forms of neural plasticity associated with migraine and other headaches, including peripheral and central sensitization, and alterations in the endogenous mechanisms of pain modulation. While these changes have been proposed to contribute to headache and pain chronification, some findings are likely the results of repetitive noxious stimulation, such as atrophy of brain areas involved in pain perception and modulation. In this review, we provide a narrative overview of recent advances on the neuroimaging, electrophysiological and genetic aspects of neural plasticity associated with the most common forms of chronic headaches, including migraine, cluster headache, tension-type headache, and medication overuse headache.

Upper cervical range of motion is impaired in patients with temporomandibular disorders

AIMS

Clinicians increasingly suggest assessment and treatment of the cervical spine in patients with temporomandibular dysfunction (TMD); however, few studies have investigated upper cervical spine mobility in people who suffer from TMD. The purpose of this study was to investigate whether patients with TMD pain (with or without headache) present with upper cervical spine impairment when compared with asymptomatic subjects.

METHODOLOGY

A single blind examiner evaluated cervical range of motion (ROM) measures including axial rotation during the flexion-rotation test (FRT) and sagittal plane ROM. Twenty asymptomatic subjects were compared with 37 subjects with pain attributed to TMD, confirmed by the Revised Research Diagnostic Criteria. Subjects with TMD were divided according to the presence of headache (26 without headache TMDNHA, 11 with headache TMDHA). One-way analysis of variance and planned orthogonal comparisons were used to determine differences in cervical mobility between groups. All subjects with TMD were positive on the FRT with restricted ROM, while none were in the control group.

RESULTS

The analysis of variance revealed significant differences between groups for the FRT F(2,54) = 57.96, P<0.001) and for sagittal ROM [F(2,54) = 5.69, P = 0.006]. Findings show that the TMDHA group had less axial rotation than group TMDNHA, and both TMD groups had less ROM than controls. For sagittal ROM, the only difference was between group TMDHA and controls.

CONCLUSIONS

Subjects with TMD had signs of upper cervical spine movement impairment, greater in those with headache. Only subjects with TMD and headache had impairment of cervical spine sagittal plane mobility. This study provides evidence for the importance of examination of upper cervical mobility determined by the FRT in patients who suffer from TMD.

Pearls and pitfalls: electrophysiology for primary headaches

BACKGROUND

Primary headaches are functional neurological diseases characterized by a dynamic cyclic pattern over time (ictal/pre-/interictal). Electrophysiological recordings can non-invasively assess the activity of an underlying nervous structure or measure its response to various stimuli, and are therefore particularly appropriate for the study of primary headaches. Their interest, however, is chiefly pathophysiological, as interindividual, and to some extent intraindividual, variations preclude their use as diagnostic tools.

AIM OF THE WORK

This article will review the most important findings of electrophysiological studies in primary headache pathophysiology, especially migraine on which numerous studies have been published.

RESULTS

In migraine, the most reproducible hallmark is the interictal lack of neuronal habituation to the repetition of various types of sensory stimulations. The mechanism subtending this phenomenon remains uncertain, but it could be the consequence of a thalamocortical dysrythmia that results in a reduced cortical preactivation level. In tension-type headache as well as in cluster headache, there seems to be an impairment of central pain-controlling mechanisms but the studies are scarce and their outcomes are contradictory. The discrepancies between studies might be as a result of methodological differences as well as patients' dissimilarities, which are also discussed.

CONCLUSIONS AND PERSPECTIVES

Electrophysiology is complementary to functional neuroimaging and will undoubtedly remain an important tool in headache research. One of its upcoming applications is to help select neurostimulation techniques and protocols that correct best the functional abnormalities detectable in certain headache disorders.

Study protocol of Prednisone in episodic Cluster Headache (PredCH): a randomized, double-blind, placebo-controlled parallel group trial to evaluate the efficacy and safety of oral prednisone as an add-on therapy in the prophylactic treatment of episodic cluster headache with verapamil

BACKGROUND

Episodic cluster headache (ECH) is a primary headache disorder that severely impairs patient's quality of life. First-line therapy in the initiation of a prophylactic treatment is verapamil. Due to its delayed onset of efficacy and the necessary slow titration of dosage for tolerability reasons prednisone is frequently added by clinicians to the initial prophylactic treatment of a cluster episode. This treatment strategy is thought to effectively reduce the number and intensity of cluster attacks in the beginning of a cluster episode (before verapamil is effective). This study will assess the efficacy and safety of oral prednisone as an add-on therapy to verapamil and compare it to a monotherapy with verapamil in the initial prophylactic treatment of a cluster episode.

METHODS AND DESIGN

PredCH is a prospective, randomized, double-blind, placebo-controlled trial with parallel study arms. Eligible patients with episodic cluster headache will be randomized to a treatment intervention with prednisone or a placebo arm. The multi-center trial will be conducted in eight German headache clinics that specialize in the treatment of ECH.

DISCUSSION

PredCH is designed to assess whether oral prednisone added to first-line agent verapamil helps reduce the number and intensity of cluster attacks in the beginning of a cluster episode as compared to monotherapy with verapamil.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00004716.

Neurostimulation in cluster headache: A review of current progress

Purpose of review

Neurostimulation has emerged as a viable treatment for intractable chronic cluster headache. Several therapeutic strategies are being investigated including stimulation of the hypothalamus, occipital nerves and sphenopalatine ganglion. The aim of this review is to provide an overview of the rationale, methods and progress for each of these.

Latest findings

Results from a randomized, controlled trial investigating sphenopalatine ganglion stimulation have just been published. Reportedly the surgery is relatively simple and it is apparently the only therapy that provides relief acutely.

Summary

The rationale behind these therapies is based on growing evidence from clinical, hormonal and neuroimaging studies. The overall results are encouraging, but unfortunately not all patients have benefited. All the mentioned therapies require weeks to months of stimulation for a prophylactic effect to occur, suggesting brain plasticity as a possible mechanism, and only stimulation of the sphenopalatine ganglion has demonstrated an acute, abortive effect. Predictors of effect for all modes of neurostimulation still need to be identified and in the future, the least invasive and most effective strategy must be preferred as first-line therapy for intractable chronic cluster headache.

Expert consensus recommendations for the performance of peripheral nerve blocks for headaches--a narrative review

OBJECTIVE

To describe a standardized methodology for the performance of peripheral nerve blocks (PNBs) in the treatment of headache disorders.

BACKGROUND

PNBs have long been employed in the management of headache disorders, but a wide variety of techniques are utilized in literature reports and clinical practice.

METHODS

The American Headache Society Special Interest Section for PNBs and other Interventional Procedures convened meetings during 2010-2011 featuring formal discussions and agreements about the procedural details for occipital and trigeminal PNBs. A subcommittee then generated a narrative review detailing the methodology.

RESULTS

PNB indications may include select primary headache disorders, secondary headache disorders, and cranial neuralgias. Special procedural considerations may be necessary in certain patient populations, including pregnancy, the elderly, anesthetic allergy, prior vasovagal attacks, an open skull defect, antiplatelet/anticoagulant use, and cosmetic concerns. PNBs described include greater occipital, lesser occipital, supratrochlear, supraorbital, and auriculotemporal injections. Technical success of the PNB should result in cutaneous anesthesia. Targeted clinical outcomes depend on the indication, and include relief of an acute headache attack, terminating a headache cycle, and transitioning out of a medication-overuse pattern. Reinjection frequency is variable, depending on the indications and agents used, and the addition of corticosteroids may be most appropriate when treating cluster headache.

CONCLUSIONS

These recommendations from the American Headache Society Special Interest Section for PNBs and other Interventional Procedures members for PNB methodology in headache disorder treatment are derived from the available literature and expert consensus. With the exception of cluster headache, there is a paucity of evidence, and further research may result in the revision of these recommendations to improve the outcome and safety of these interventions.

Head pain referral during examination of the neck in migraine and tension-type headache

OBJECTIVE

To investigate if and to what extent typical head pain can be reproduced in tension-type headache (TTH), migraine without aura sufferers, and controls when sustained pressure was applied to the lateral posterior arch of C1 and the articular pillar of C2, stressing the atlantooccipital and C2-3 segments respectively.

BACKGROUND

Occipital and neck symptoms often accompany primary headache, suggesting involvement of cervical afferents in central pain processing mechanisms in these disorders. Referral of head pain from upper cervical structures is made possible by convergence of cervical and trigeminal nociceptive afferent information in the trigemino-cervical nucleus. Upper cervical segmental and C2-3 zygapophysial joint dysfunction is recognized as a potential source of noxious afferent information and is present in primary headache sufferers. Furthermore, referral of head pain has been demonstrated from symptomatic upper cervical segments and the C2-3 zygapophysial joints, suggesting that head pain referral may be a characteristic of cervical afferent involvement in headache.

METHODS

Thirty-four headache sufferers and 14 controls were examined interictally. Headache patients were diagnosed according the criteria of the International Headache Society and comprised 20 migraine without aura (females n = 18; males n = 2; average age 35.3 years) and 14 TTH sufferers (females n = 11; males n = 3; average age 30.7 years). Two techniques were used specifically to stress the atlantooccipital segments (Technique 1 - C1) and C2-3 zygapophysial joints (Technique 2 - C2). Two techniques were also applied to the arm--the common extensor origin and the mid belly of the biceps brachii. Participants reported reproduction of head pain with "yes" or "no" and rated the intensity of head pain and local pressure of application on a scale of 0 -10, where 0 = no pain and 10 = intolerable pain.

RESULTS

None of the subjects reported head pain during application of techniques on the arm. Head pain referral during the cervical examination was reported by 8 of 14 (57%) control participants, all TTH patients and all but 1 migraineur (P < .002). In each case, participants reported that the referred head pain was similar to the pain they usually experienced during TTH or migraine. The frequency of head pain referral was identical for Techniques 1 and 2. The intensity of referral did not differ between Technique 1 and Technique 2 or between groups. Tenderness ratings to thumb pressure were comparable between the Techniques 1 and 2 when pressure was applied to C1 and C2 respectively and across groups. Similarly, there were no significant differences for tenderness ratings to thumb pressure between Technique 1 and Technique 2 on the arm or between groups. While tenderness ratings to thumb pressure for Technique 2 were similar for both referral (n = 41) and non-referral (n = 7) groups, tenderness ratings for Technique 1 in the referral group were significantly greater when compared with the non-referral group (P = .01).

CONCLUSIONS

Our data support the continuum concept of headache, one in which noxious cervical afferent information may well be significantly underestimated. The high incidence of reproduction of headache supports the evaluation of musculoskeletal features in patients presenting with migrainous and TTH symptoms. This, in turn, may have important implications for understanding the pathophysiology of headache and developing alternative treatment options.

Occipital nerve block is effective in craniofacial neuralgias but not in idiopathic persistent facial pain

Occipital nerve block (ONB) has been used in several primary headache syndromes with good results. Information on its effects in facial pain is sparse. In this chart review, the efficacy of ONB using lidocaine and dexamethasone was evaluated in 20 patients with craniofacial pain syndromes comprising 8 patients with trigeminal neuralgia, 6 with trigeminal neuropathic pain, 5 with persistent idiopathic facial pain and 1 with occipital neuralgia. Response was defined as an at least 50% reduction of original pain. Mean response rate was 55% with greatest efficacy in trigeminal (75%) and occipital neuralgia (100%) and less efficacy in trigeminal neuropathic pain (50%) and persistent idiopathic facial pain (20%). The effects lasted for an average of 27 days with sustained benefits for 69, 77 and 107 days in three patients. Side effects were reported in 50%, albeit transient and mild in nature. ONBs are effective in trigeminal pain involving the second and third branch and seem to be most effective in craniofacial neuralgias. They should be considered in facial pain before more invasive approaches, such as thermocoagulation or vascular decompression, are performed, given that side effects are mild and the procedure is minimally invasive.

Blocking the greater occipital nerve: utility in headache management

Occipital nerve block has been part of headache medicine for more than half a century, with injection techniques and solutions varying greatly. Most studies have been case series and many show benefit for patients with migraine, cluster headache, and postconcussive headache. A double-blind, controlled trial of cluster headache has demonstrated that injectable steroids with local anesthetics benefit cluster headache patients. A double-blind, controlled trial of nerve blocks in occipital neuralgia, which may have actually been chronic migraine, was positive.

Greater occipital nerve block in chronic migraine

Headache syndromes often involve occipital and neck symptoms suggesting a functional connectivity between nociceptive trigeminal and cervical afferents. Several studies have suggested that pain relief in migraine and other types of headache can be achieved by local injections of steroids, local anaesthetics or a mixture of both in the area of greater occipital nerve (GON). Usually greater occipital nerve block (GONB) is performed by using local anaesthetics alone or with steroid. The rationale of performing a GONB for the treatment of chronic headache states is on the anatomical connections between trigeminal and upper cervical sensory fibres at the level of the trigeminal nucleus caudalis. However, the reason for the improvement after GONB in primary headache is unknown. The objective of this study is to determine whether adding triamcinolone to local anaesthetics increased the efficacy of GONB and trigger point injections (TPIs) for chronic migraine (TM). Patients with TM were randomized to receive GONB and TPIs using lidocaine 2% and bupivacaine 0.5% + either saline or triamcinolone 40 mg. Particularly, a 10-ml syringe containing 4.5 ml of lidocaine 2%, 4.5 ml of bupivacaine 0.5% and 1 ml of either saline (group A) or triamcinolone 40 mg/ml (group B) was prepared for each patients. Patients were given bilateral GONB and TPIs in the cervical paraspinal and trapezius muscles bilaterally. 2 ml were injected into each GON at the medial third of the distance between the occipital protuberance and the mastoid process. In addition, 0.5 ml was injected into each of the 12 trigger points. The total injected volume was 10 ml. The primary outcome measure was the change in mean headache severity from before injection to 20 min after in the two groups. Secondary outcome measures were the change in mean neck pain, photophobia and phonofobia severity from before injection to 20 min after in the two groups. Patients documented headache and severity of associated symptoms for 4 weeks after injection. Changes in symptom severity were compared between the two groups. Thirty-seven patients were included. Twenty minutes after injection, mean headache severity decreased by 3.2 points in group A (p < 0.01) and by 3.1 points in group B (p < 0.01). Mean neck pain severity decreased by 1.5 points in group A (p < 0.01) and by 1.7 points in group B (p < 0.01). Mean duration of being headache-free was 2.7 +/- 3.8 days in group A and 1.0 +/- 1.1 days in group B (p = 0.67). None of the outcome measures differed significantly between the two groups. Both treatments were full tolerated. In our study, adding triamcinolone to local anaesthetic when performing GONB and TPIs was not associated with improved outcome in the sample of patients with TM. In both groups, the procedure resulted in significant and rapid relief of headache, neck pain, photophobia and phonofobia.

Peripheral nerve blocks and trigger point injections in headache management - a systematic review and suggestions for future research

Interventional procedures such as peripheral nerve blocks (PNBs) and trigger point injections (TPIs) have long been used in the treatment of various headache disorders. There are, however, little data on their efficacy for the treatment of specific headache syndromes. Moreover, there is no widely accepted agreement among headache specialists as to the optimal technique of injection, type, and doses of the local anesthetics used, and injection regimens. The role of corticosteroids in this setting is also debated. We performed a PubMed search of the literature to find studies on PNBs and TPIs for headache treatment. We classified the abstracted studies based on the procedure performed and the treated condition. We found few controlled studies on the efficacy of PNBs for headaches, and virtually none on the use of TPIs for this indication. The most widely examined procedure in this setting was greater occipital nerve block, with the majority of studies being small and non-controlled. The techniques, as well as the type and doses of local anesthetics used for nerve blockade, varied greatly among studies. The specific conditions treated also varied, and included both primary (eg, migraine, cluster headache) and secondary (eg, cervicogenic, posttraumatic) headache disorders. Trigeminal (eg, supraorbital) nerve blocks were used in few studies. Results were generally positive, but should be taken with reservation given the methodological limitations of the available studies. The procedures were generally well tolerated. Evidently, there is a need to perform more rigorous clinical trials to clarify the role of PNBs and TPIs in the management of various headache disorders, and to aim at standardizing the techniques used for the various procedures in this setting.

Sonographic visualization and ultrasound-guided blockade of the greater occipital nerve: a comparison of two selective techniques confirmed by anatomical dissection

BACKGROUND

Local anaesthetic blocks of the greater occipital nerve (GON) are frequently performed in different types of headache, but no selective approaches exist. Our cadaver study compares the sonographic visibility of the nerve and the accuracy and specificity of ultrasound-guided injections at two different sites.

METHODS

After sonographic measurements in 10 embalmed cadavers, 20 ultrasound-guided injections of the GON were performed with 0.1 ml of dye at the classical site (superior nuchal line) followed by 20 at a newly described site more proximal (C2, superficial to the obliquus capitis inferior muscle). The spread of dye and coloration of nerve were evaluated by dissection.

RESULTS

The median sonographic diameter of the GON was 4.2 x 1.4 mm at the classical and 4.0 x 1.8 mm at the new site. The nerves were found at a median depth of 8 and 17.5 mm, respectively. In 16 of 20 in the classical approach and 20 of 20 in the new approach, the nerve was successfully coloured with the dye. This corresponds to a block success rate of 80% (95% confidence interval: 58-93%) vs 100% (95% confidence interval: 86-100%), which is statistically significant (McNemar's test, P=0.002).

CONCLUSIONS

Our findings confirm that the GON can be visualized using ultrasound both at the level of the superior nuchal line and C2. This newly described approach superficial to the obliquus capitis inferior muscle has a higher success rate and should allow a more precise blockade of the nerve.

Occipital nerve blocks: when and what to inject?

INTRODUCTION

Occipital nerve block (ONB) is a promising treatment for headaches. Its indications, selection criteria, and best techniques are not clear, however.

OBJECTIVE

To summarize in narrative format what is known about ONBs and what needs to be learned.

METHODS

MD Consult and Google Scholar were searched using the terms occipital, suboccipital, block, and injection to identify relevant articles that were reviewed. This process was repeated for all additional pertinent articles identified from these articles, and so on, until no additional articles were identified.

RESULTS

A total of 21 articles were identified.

CONCLUSIONS

Occipital nerve block is an effective treatment for cervicogenic headache, cluster headache, and occipital neuralgia. While a double blinded randomized placebo controlled clinical trial is lacking, multiple open label studies reported favorable results for migraine. Two other possible uses of ONB worthy of further study are use as a rescue treatment and as an adjunctive treatment for medication overuse headache. ONB may be effective for tension headache, but only under very specific circumstances. ONB is either ineffective or only effective under as yet unstudied circumstances for hemicrania continua and chronic paroxysmal hemicrania. Some practitioners use occipital nerve (ON) tenderness to palpation (TTP) or reproduction of headache pain with ON pressure (RHPONP) as selection criteria for identifying appropriate patients. While only a clinical trial can produce a definitive answer, current evidence suggests that these selection criteria are not necessary for cervicogenic headache or cluster headache. Occipital neuralgia by definition involves TTP of the ONs. Whether RHPONP or ON TTP predicts success in migraine is unclear, and may relate to whether steroids are used. A single blinded randomized controlled trial evaluating local anesthetic with steroids vs local anesthetic alone for transformed migraine reported slightly worse results with steroids, but there are several alternate explanations for this finding other than steroids being counterproductive. The technique of repetitive ONBs deserves further study.

The role of nerve blocks and botulinum toxin injections in the management of cluster headaches

Cluster headache (CH) is a primary headache syndrome that is classified with the trigeminal autonomic cephalalgias. CH treatment involves three steps: acute attack management, transitional therapy, and preventive therapy. Greater occipital nerve block has been shown to be an effective alternative bridge therapy to oral steroids in CH. Botulinum toxin type A has recently been studied as a new preventive treatment for patients with chronic CH, with limited success.