Towards a definition of intractable headache for use in clinical practice and trials

[Diagnosis and therapies of refractory migraine]

It is well known that some migraine patients recognize the change of their migraine characteristics over time. These patients often complain chronic daily headaches instead of episodic attacks of migraine. Such chronic headaches are resistant to medication, and called refractory or intractable migraine. Refractory migraine is a term, which has been used for many years, but until recently, there has been little attention paid to its definition. The criteria used for diagnosis of refractory migraine have varied considerably. In most circumstances, however, the definition has included a poor response to "standard" preventive medications. This review article introduces the proposed criteria for definition of refractory migraine and the therapeutic strategies against refractory migraine.

Treatment costs and indirect costs of cluster headache: A health economics analysis

BACKGROUND

Cluster headache (CH) is the most frequent trigemino-autonomic cephalgia. CH can manifest as episodic (eCH) or chronic cluster headache (cCH) causing significant burden of disease and requiring attack therapy and prophylactic treatment.

METHODS

Treatment costs (direct costs) due to healthcare utilisation, as well as costs caused by disability and reduction in earning capacity (indirect costs), were obtained using a questionnaire in CH patients treated in a tertiary headache centre based at the University Duisburg-Essen over a 6-month period.

RESULTS

A total 179 patients (72 cCH, 107 eCH) were included. Mean attack frequency was 3.5 ± 2.5 per day. Mean direct and indirect costs for one person were €5963 in the 6-month period. Direct costs were positively correlated with attack frequency (r = 0.467, p < 0.001). Burden of disease measured with HIT-6 showed a significant correlation with attack frequency (r = 0.467, p < 0.001). Twenty-four (13.4%) of the participants were disabled and not able to work.

CONCLUSION

CH leads to major socioeconomic impact on patients as well as society due to direct healthcare costs and indirect costs caused by loss of working capacity.

Cluster headache: clinical features and therapeutic options

BACKGROUND

Cluster headache is the most common type of trigemino-autonomic headache, affecting ca. 120 000 persons in Germany alone. The attacks of pain are in the periorbital area on one side, last 90 minutes on average, and are accompanied by trigemino-autonomic manifestations and restlessness. Most patients have episodic cluster headache; about 15% have chronic cluster headache, with greater impairment of their quality of life. The attacks often possess a circadian and seasonal rhythm.

METHOD

Selective literature review

RESULTS

Oxygen inhalation and triptans are effective acute treatment for cluster attacks. First-line drugs for attack prophylaxis include verapamil and cortisone; alternatively, lithium and topiramate can be given. Short-term relief can be obtained by the subcutaneous infiltration of local anesthetics and steroids along the course of the greater occipital nerve, although most of the evidence in favor of this is not derived from randomized clinical trials. Patients whose pain is inadequately relieved by drug treatment can be offered newer, invasive treatments, such as deep brain stimulation in the hypothalamus (DBS) and bilateral occipital nerve stimulation (ONS).

CONCLUSION

Pharmacotherapy for the treatment of acute attacks and for attack prophylaxis is effective in most patients. For the minority who do not gain adequate relief, newer invasive techniques are available in some referral centers. Definitive conclusions as to their value cannot yet be drawn from the available data.

Refractory migraine in a headache clinic population

BACKGROUND

Many migraineurs who seek care in headache clinics are refractory to treatment, despite advances in headache therapies. Epidemiology is poorly characterized, because diagnostic criteria for refractory migraine were not available until recently. We aimed to determine the frequency of refractory migraine in patients attended in the Headache Unit in a tertiary care center, according to recently proposed criteria.

METHODS

The study population consisted of a consecutive sample of 370 patients (60.8% females) with a mean age of 43 years (range 14-86) evaluated for the first time in our headache unit over a one-year period (between October 2008 and October 2009). We recorded information on clinical features, previous treatments, Migraine Disability Assessment Score (MIDAS), and final diagnosis.

RESULTS

Overall migraine and tension-type headache were found in 46.4% and 20.5% of patients, respectively. Refractory migraine was found in 5.1% of patients. In refractory migraineurs, the mean MIDAS score was 96, and 36.8% were medication-overusers.

CONCLUSIONS

Refractory migraine is a relatively common and very disabling condition between the patients attended in a headache unit. The proposed operational criteria may be useful in identifying those patients who require care in headache units, the selection of candidates for combinations of prophylactic drugs or invasive treatments such as neurostimulation, but also to facilitate clinical studies in this patient group.

High cervical spinal cord stimulation for chronic cluster headache

BACKGROUND

Cluster headache (CH) is the most painful and debilitating primary headache syndrome. Conventional treatment combines acute and prophylactic drugs. Also with maximal therapy a substantial proportion of patients do not experience a meaningful prevention or pain relief. Recent case series and early trials have suggested that occipital nerve stimulation can be very effective in the management of intractable CH.

METHODS

Seven patients with medically intractable chronic cluster headache were implanted with high cervical epidural electrodes. After a median test phase of 10 days (range 4-19 days) an impulse generator was implanted subcutaneously. Mean follow up was 23 months (median 12 months, range 3-78 months).

RESULTS

All patients showed significant treatment effects. In all patients, improvement occurred immediately after electrode implantation. The mean attack frequency decreased, as well as the mean duration and intensity of attacks. Also, depression, anxiety, and pain-related impairment scores decreased and medication intake was markedly reduced.

CONCLUSIONS

In this prospective series, high cervical spinal cord stimulation shows an effect size equal or larger than occipital nerve stimulation with immediate onset after surgery and may serve as a valuable additional treatment option of intractable cluster headache in the future.

Central modulation in cluster headache patients treated with occipital nerve stimulation: an FDG-PET study

BACKGROUND

Occipital nerve stimulation (ONS) has raised new hope for drug-resistant chronic cluster headache (drCCH), a devastating condition. However its mode of action remains elusive. Since the long delay to meaningful effect suggests that ONS induces slow neuromodulation, we have searched for changes in central pain-control areas using metabolic neuroimaging.

METHODS

Ten drCCH patients underwent an 18FDG-PET scan after ONS, at delays varying between 0 and 30 months. All were scanned with ongoing ONS (ON) and with the stimulator switched OFF.

RESULTS

After 6-30 months of ONS, 3 patients were pain free and 4 had a ≥ 90% reduction of attack frequency (responders). In all patients compared to controls, several areas of the pain matrix showed hypermetabolism: ipsilateral hypothalamus, midbrain and ipsilateral lower pons. All normalized after ONS, except for the hypothalamus. Switching the stimulator ON or OFF had little influence on brain glucose metabolism. The perigenual anterior cingulate cortex (PACC) was hyperactive in ONS responders compared to non-responders.

CONCLUSIONS

Metabolic normalization in the pain neuromatrix and lack of short-term changes induced by the stimulation might support the hypothesis that ONS acts in drCCH through slow neuromodulatory processes. Selective activation in responders of PACC, a pivotal structure in the endogenous opioid system, suggests that ONS could restore balance within dysfunctioning pain control centres. That ONS is nothing but a symptomatic treatment might be illustrated by the persistent hypothalamic hypermetabolism, which could explain why autonomic attacks may persist despite pain relief and why cluster attacks recur shortly after stimulator arrest. PET studies on larger samples are warranted to confirm these first results.

Occipital nerve stimulation for the treatment of intractable chronic migraine headache: ONSTIM feasibility study

BACKGROUND

Medically intractable chronic migraine (CM) is a disabling illness characterized by headache ≥15 days per month.

METHODS

A multicenter, randomized, blinded, controlled feasibility study was conducted to obtain preliminary safety and efficacy data on occipital nerve stimulation (ONS) in CM. Eligible subjects received an occipital nerve block, and responders were randomized to adjustable stimulation (AS), preset stimulation (PS) or medical management (MM) groups.

RESULTS

Seventy-five of 110 subjects were assigned to a treatment group; complete diary data were available for 66. A responder was defined as a subject who achieved a 50% or greater reduction in number of headache days per month or a three-point or greater reduction in average overall pain intensity compared with baseline. Three-month responder rates were 39% for AS, 6% for PS and 0% for MM. No unanticipated adverse device events occurred. Lead migration occurred in 12 of 51 (24%) subjects.

CONCLUSION

The results of this feasibility study offer promise and should prompt further controlled studies of ONS in CM.

Deep brain stimulation in trigeminal autonomic cephalalgias

Cluster headache (CH), paroxysmal hemicrania (PH), and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT syndrome) are primary headaches grouped together as trigeminal autonomic cephalalgias (TACs). All are characterized by short-lived unilateral head pain attacks associated with oculofacial autonomic phenomena. Neuroimaging studies have demonstrated that the posterior hypothalamus is activated during attacks, implicating hypothalamic hyperactivity in TAC pathophysiology and suggesting stimulation of the ipsilateral posterior hypothalamus as a means of preventing intractable CH. After almost 10 years of experience, hypothalamic stimulation has proved successful in preventing pain attacks in approximately 60% of the 58 documented chronic drug-resistant CH patients implanted at various centers. Positive results have also been reported in drug-resistant SUNCT and PH. Microrecording studies on hypothalamic neurons are increasingly being performed and promise to make it possible to more precisely identify the target site. The implantation procedure has generally proved safe, although it carries a small risk of brain hemorrhage. Long-term stimulation is proving to be safe: studies on patients under continuous hypothalamic stimulation have identified nonsymptomatic impairment of orthostatic adaptation as the only noteworthy change. Studies on pain threshold in chronically stimulated patients show increased threshold for cold pain in the distribution of the first trigeminal branch ipsilateral to stimulation. When the stimulator is switched off, changes in sensory and pain thresholds do not occur immediately, indicating that long-term hypothalamic stimulation is necessary to produce sensory and nociceptive changes, as also indicated by clinical experience that CH attacks are brought under control only after weeks of stimulation. Infection, transient loss of consciousness, and micturition syncope have been reported, but treatment interruption usually is not required.

Occipital nerve stimulation for headache disorders

Occipital nerve stimulation (ONS) was originally described in the treatment of occipital neuralgia. However, the spectrum of possible indications has expanded in recent years to include primary headache disorders, such as migraine and cluster headaches. Retrospective and some prospective studies have yielded encouraging results, and evidence from controlled clinical trials is emerging, offering hope for refractory headache patients. In this article we discuss the scientific rationale to use ONS to treat headache disorders, with emphasis on the trigeminocervical complex. ONS is far from a standardized technique at the moment and the recent literature on the topic is reviewed, both with respect to the procedure and its possible complications. An important way to move forward in the scientific evaluation of ONS to treat refractory headache is the clinical phenotyping of patients to identify patients groups with the highest likelihood to respond to this modality of treatment. This requires multidisciplinary assessment of patients. The development of ONS as a new treatment for refractory headache offers an exciting prospect to treat our most disabled headache patients. Data from ongoing controlled trials will undoubtedly shed new light on some of the unresolved questions.

Safety and efficacy of deep brain stimulation in refractory cluster headache: a randomized placebo-controlled double-blind trial followed by a 1-year open extension

Chronic cluster headache (CCH) is a disabling primary headache, considering the severity and frequency of pain attacks. Deep brain stimulation (DBS) has been used to treat severe refractory CCH, but assessment of its efficacy has been limited to open studies. We performed a prospective crossover, double-blind, multicenter study assessing the efficacy and safety of unilateral hypothalamic DBS in 11 patients with severe refractory CCH. The randomized phase compared active and sham stimulation during 1-month periods, and was followed by a 1-year open phase. The severity of CCH was assessed by the weekly attacks frequency (primary outcome), pain intensity,sumatriptan injections, emotional impact (HAD) and quality of life (SF12). Tolerance was assessed by active surveillance of behavior, homeostatic and hormonal functions.During the randomized phase, no significant change in primary and secondary outcome measures was observed between active and sham stimulation. At the end of the open phase, 6/11 responded to the chronic stimulation(weekly frequency of attacks decrease [50%), including three pain-free patients. There were three serious adverse events, including subcutaneous infection, transient loss of consciousness and micturition syncopes. No significant change in hormonal functions or electrolytic balance was observed. Randomized phase findings of this study did not support the efficacy of DBS in refractory CCH, but open phase findings suggested long-term efficacy in more than 50% patients, confirming previous data, without high morbidity. Discrepancy between these findings justifies additional controlled studies (clinicaltrials.gov number NCT00662935).

Neurostimulation therapy in intractable headaches

A proportion of chronic headache patients become refractory to medical treatment and severely disabled. In such patients various neurostimulation methods have been proposed, ranging from invasive procedures such as deep-brain stimulation to minimally invasive ones like occipital nerve stimulation. They have been applied in single cases or small series of patients affected with varying headache disorders: cervicogenic headache, hemicrania continua, posttraumatic headache, chronic migraine, and cluster headache. Although favorable results were reported overall, it is premature to consider neurostimulation as a treatment with established utility in refractory headaches. At present, the most detailed clinical studies have been performed in intractable chronic cluster headache (iCCH) patients, who represent about 1% of all chronic cluster headache (CCH) patients. Various lesional interventions have been attempted in these patients, none with lasting benefits. In recent years, non-destructive neurostimulation methods have raised new hope. Hypothalamic deep-brain stimulation (hDBS) acts rapidly and has lasting efficacy, but is not without risk. Occipital nerve stimulation (ONS) was studied in two trials on a total of 17 iCCH patients. Clinical efficacy was found to be very satisfactory by most patients and by the investigators. Although slightly less efficacious than hDBS, ONS has the advantage of being rather harmless and reversible. At this stage, it should be preferred as first-line invasive therapy for iCCH. Recent case reports mention the efficacy of supraorbital (SNS) and vagal (VNS) nerve stimulation. Whether these neurostimulation methods have a place in the management of iCCH patients remains to be determined.

Refractory migraine and chronic migraine: pathophysiological mechanisms

Despite increased understanding of primary headaches and their treatment, the underlying causes of refractory migraine remain unknown. This note considers potential genetic, structural, functional and pharmacological factors that could contribute to this relatively intractable condition. Further understanding of refractory migraine will require the use of medical imaging technologies, clinical experimental medicine studies on novel pharmacological agents and astute observations in clinical practice to direct potential novel therapeutic approaches.

When should "chronic migraine" patients be considered "refractory" to pharmacological prophylaxis?

Patients with chronic headache forms evolving from a previous episodic migraine ('chronic migraine') are often difficult to treat. In this paper we focus attention on aspects we believe important for producing a definition of "refractory" in relation to this headache form. We propose a "chronic migraine" patient should be considered "refractory" to pharmacological prophylaxis when adequate trials of preventive therapies at adequate doses have failed to reduce headache frequency and improve headache-related disability and, in patients with medication overuse, reduce the consumption of symptomatic drugs. However before a definition of "refractory" chronic migraine can become established, generally accepted diagnostic criteria and treatment guidelines for this condition need to be developed.

Refractory migraine and chronic migraine: pathophysiological mechanisms

Migraine is a complex disorder of the brain whose mechanisms are only now being unravelled. It is common, disabling, and economically costly. Brain imaging has suggested a role for the brainstem. While the disorder is almost certainly inherited, the degree to which this contributes to a treatment refractory state is not clear. Indeed, no specific structural or pharmacological explanation can be seen from the data as they have been generated. It is clear that patients with more frequent headache are very likely to go on to even more frequent headache, but again these data are complex. A challenge going forward is to establish the biology of these very challenging patients who undoubtedly have substantial disability.

Refractory headache: historical perspective, need, and purposes for an operational definition

The study of migraine has yielded many benefits for headache patients. Little research, however, has been performed on refractory migraine (RM) headache, a term often used interchangeably with intractable migraine. This may be a consequence of a lack of a well-accepted definition. In a survey performed by the Refractory Headache Special Interest Section (RHSIS) on the American Headache Society (AHS) in 2006, 58% of the members agreed that a definition for refractory headache should be added to the International Classification of Headache Disorders-2. A PubMed search identified 21 articles that defined refractory or intractable headache/migraine. Sixteen (76%) defined the term "refractory" and 5 (24%) defined the term "intractable." Many of these definitions did not address the need for an adequate trial of a preventive medicine, disability, and medication overuse. An operational definition will allow us to better characterize the disorder, address unmet medical needs, and identify the most effective treatments. RHSIS of the AHS has proposed a definition of RM. It is our hope that this definition will spur interest in this entity and will lead to further research in the area.

Guidelines for Controlled Trials of Prophylactic Treatment of Chronic Migraine in Adults

In 1991 the Clinical Trials Subcommittee of the International Headache Society (IHS) developed and published its first edition of the Guidelines on controlled trials of drugs in episodic migraine because only quality trials can form the basis for international collaboration on drug therapy, and these Guidelines would ‘improve the quality of controlled clinical trials in migraine’. With the current trend for large multinational trials, there is a need for increased awareness of methodological issues in clinical trials of drugs and other treatments for chronic migraine. These Guidelines are intended to assist in the design of well-controlled clinical trials of chronic migraine in adults, and do not apply to studies in children or adolescents.

Neurostimulation in primary headache syndromes

Neurostimulation therapy involves the use of peripheral or central nerve electrical stimulation approaches for the treatment of medically intractable headache. Currently, for peripheral stimulation the main approach is that of occipital nerve stimulation, while for central stimulation deep-brain approaches with the target of the region of the posterior hypothalamic gray matter have been explored. Target conditions include migraine and the trigeminal autonomic cephalalgias: cluster headache, paroxysmal hemicrania and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing/cranial autonomic features (SUNCT/SUNA), as well as hemicrania continua. The initial results are encouraging and given the very significant disability of medically intractable primary headaches, this is a very promising area for patients and physicians alike.

Emerging therapies for migraine

Migraine is a common disabling brain disorder that--considering its clinical and economic impact--is understudied and in need of additional management options. Currently, treatments are classified as preventive or acute-attack therapies, although it is expected that this distinction will become blurred over time. The gap-junction blocker tonabersat, an inducible nitric oxide synthase (NOS) inhibitor and botulinum toxin A are all being investigated in clinical trials as preventive therapies. Device-based approaches using neurostimulation of the occipital nerve have provided promising results, whereas the first study of patent foramen ovale closure for migraine prevention produced disappointing results. Calcitonin gene-related peptide receptor antagonists, vanilloid TRPV1 receptor antagonists and NOS inhibitors are all being investigated in clinical trials for acute migraine. There is much cause for optimism in this area of neurology and considerable benefit awaits our patients.

Uncontrolled headache induced by oxcarbazepine

Headache induced by acute exposure to a specific drug constitutes an idiosyncratic side effect. Metabolic imbalance appears as the leading aetiology, among several other hypotheses. Either primary headaches show a higher susceptibility to this idiosyncratic reaction or a drug-induced primary headache evolves in intensity and duration, becoming uncontrolled until the complete discontinuation of the drug in consideration. The goal of this study is to describe three patients diagnosed with migraine and epilepsy (both under control) who evolved into status migrainosus after the introduction of oxcarbazepine (OXC), as part of a switch off from carbamazepine (CBZ). Twenty-four to seventy-two hours following the switch, all patients developed intractable headache, despite the use of different symptomatic drugs. Complete recovery of the headache symptoms occurred only after OXC was discontinued. We discuss the potential mechanisms associated to OXC and status migrainosus, drug-induced headaches and uncontrolled headaches.

Trigeminal Autonomic Cephalalgias: Current and Future Treatments

The trigeminal autonomic cephalgias include cluster headache, paroxysmal hemicrania, and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT). The evidence for the current treatment options for each of these syndromes is considered, including oxygen, sumatriptan, and verapamil in cluster headache, indomethacin in paroxysmal hemicrania, and intravenous lidocaine and lamotrigine in SUNCT. Some treatments such as topiramate have an effect in all of these, as well as in migraine and other pain syndromes. The involvement of the hypothalamus in functional imaging studies implies that this may be a substrate for targeting treatment options in the future.

Trigeminal autonomic cephalalgias: Diagnosis and treatment

The trigeminal autonomic cephalalgias (TACs) are a group of primary headache disorders characterized by unilateral head pain that occurs in association with ipsilateral cranial autonomic features. The TACs include cluster headache, paroxysmal hemicrania, and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and its close relative short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA). These syndromes cause patients considerable disability and certainly very significant suffering. They are distinguished by the frequency of attacks of pain, the length of the attacks, and very characteristic responses to medical therapy, such that the diagnosis can usually be made clinically, which is important because it completely dictates therapy. The management of TACs can be very rewarding for physicians and highly beneficial to patients.

Occipital nerve stimulation for drug-resistant chronic cluster headache: a prospective pilot study

BACKGROUND

Drug-resistant chronic cluster headache (drCCH) is a devastating disorder for which various destructive procedures have been tried unsuccessfully. Occipital nerve stimulation (ONS) is a new, safe strategy for intractable headaches. We undertook a prospective pilot trial of ONS in drCCH to assess clinical efficacy and pain perception.

METHODS

Eight patients with drCCH had a suboccipital neurostimulator implanted on the side of the headache and were asked to record details of frequency, intensity, and symptomatic treatment for their attacks in a diary before and after continuous ONS. To detect changes in cephalic and extracephalic pain processing we measured electrical and pressure pain thresholds and the nociceptive blink reflex.

FINDINGS

Two patients were pain free after a follow-up of 16 and 22 months; one of them still had occasional autonomic attacks. Three patients had around a 90% reduction in attack frequency. Two patients, one of whom had had the implant for only 3 months, had improvement of around 40%. Mean follow-up was 15.1 months (SD 9.5, range 3-22). Intensity of attacks tends to decrease earlier than frequency during ONS and, on average, is improved by 50% in remaining attacks. All but one patient were able to substantially reduce their preventive drug treatment. Interruption of ONS by switching off the stimulator or because of an empty battery was followed within days by recurrence and increase of attacks in all improved patients. ONS did not significantly modify pain thresholds. The amplitude of the nociceptive blink reflex increased with longer durations of ONS. There were no serious adverse events.

INTERPRETATION

ONS could be an efficient treatment for drCCH and could be safer than deep hypothalamic stimulation. The delay of 2 months or more between implantation and significant clinical improvement suggests that the procedure acts via slow neuromodulatory processes at the level of upper brain stem or diencephalic centres.

Treatment of medically intractable cluster headache by occipital nerve stimulation: long-term follow-up of eight patients

BACKGROUND

Cluster headache is a form of primary headache that features repeated attacks of excruciatingly severe headache usually occurring several times a day. Patients with chronic cluster headache have unremitting illness that necessitates daily preventive medical treatment for years. When medically intractable, the condition has previously been treatable only with cranially invasive or neurally destructive methods.

METHODS

Eight patients with medically intractable chronic cluster headache were implanted in the suboccipital region with electrodes for occipital nerve stimulation. Other than the first patient, who was initially stimulated unilaterally before being stimulated bilaterally, all patients were stimulated bilaterally during treatment.

FINDINGS

At a median follow-up of 20 months (range 6-27 months for bilateral stimulation), six of eight patients reported responses that were sufficiently meaningful for them to recommend the treatment to similarly affected patients with chronic cluster headache. Two patients noticed a substantial improvement (90% and 95%) in their attacks; three patients noticed a moderate improvement (40%, 60%, and 20-80%) and one reported mild improvement (25%). Improvements occurred in both frequency and severity of attacks. These changes took place over weeks or months, although attacks returned in days when the device malfunctioned (eg, with battery depletion). Adverse events of concern were lead migrations in one patient and battery depletion requiring replacement in four.

INTERPRETATION

Occipital nerve stimulation in cluster headache seems to offer a safe, effective treatment option that could begin a new era of neurostimulation therapy for primary headache syndromes.