Serotonin receptor adaptation in patients with analgesic-induced headache

The Evolution of Medication Overuse Headache: History, Pathophysiology and Clinical Update

Medication overuse headache (MOH), the development or worsening of chronic headache resulting from frequent and excessive intake of medications used for acute treatment of headache, is a common secondary headache disorder and is associated with significant personal and societal burdens. The plausible physiologic mechanism is that chronic exposure to acute care migraine treatment leads to suppression of endogenous antinociceptive systems, consequently facilitating the trigeminal nociceptive process via up-regulation of the calcitonin gene-related peptide (CGRP) system. Recognizing and preventing its development is an integral aspect of migraine management, as medication overuse is a modifiable risk factor in the progression from episodic to chronic migraine. Over the years, MOH has been difficult to treat and has generated much controversy. Ongoing debates exist over the diagnostic criteria and treatment strategies, particularly regarding the roles of formal detoxification and preventive treatment. The arrival of the anti-CGRP monoclonal antibodies has also challenged our views of MOH and its treatment. This review outlines the evolution of MOH diagnostic criteria, presents the current understanding of MOH pathogenesis and discusses the debates over its development and treatment. Data on the efficacy of anti-CGRP monoclonal antibodies in the setting of medication overuse is also presented. These results indicate that patients with medication overuse, who are treated with these new medications, may not need to be detoxified in order to treat MOH. In light of these developments, it is likely that in the future MOH will be more readily diagnosed and treatment will result in better outcomes.

Evaluation of LY573144 (lasmiditan) in a preclinical model of medication overuse headache

BACKGROUND

Medication overuse is a significant issue that complicates the treatment of headache disorders. The most effective medications for the acute treatment of migraine all have the capacity to induce medication overuse headache (MOH). Novel acute migraine-specific treatments are being developed. However, because the mechanism(s) underlying medication overuse headache are not well understood, it is difficult to predict whether any particular acute medication will induce MOH in susceptible individuals. LY573144 (lasmiditan), a 5-HT_1F receptor agonist, has recently been shown to be effective in the acute treatment of migraine in phase 3 trials. The aim of this study is to determine whether frequent administration of lasmiditan induces behaviors consistent with MOH in a pre-clinical rat model.

METHODS

Sprague Dawley rats were administered six doses of lasmiditan (10 mg/kg), sumatriptan (10 mg/kg), or sterile water orally over 2 weeks and cutaneous allodynia was evaluated regularly in the periorbital and hindpaw regions using von Frey filaments. Testing continued until mechanosensitivity returned to baseline levels. Rats were then submitted to bright light stress (BLS) or nitric oxide (NO) donor administration and were again evaluated for cutaneous allodynia in the periorbital and hindpaw regions hourly for 5 hours.

RESULTS

Both lasmiditan and sumatriptan exhibited comparable levels of drug-induced cutaneous allodynia in both the periorbital and hindpaw regions, which resolved after cessation of drug administration. Both lasmiditan and sumatriptan pre-treatment resulted in cutaneous allodynia that was evoked by either BLS or NO donor.

CONCLUSIONS

In a pre-clinical rat model of MOH, oral lasmiditan, like sumatriptan, induced acute transient cutaneous allodynia in the periorbital and hindpaw regions that after resolution could be re-evoked by putative migraine triggers. These results suggest that lasmiditan has the capacity to induce MOH through persistent latent peripheral and central sensitization mechanisms.

Altered activity in the nucleus raphe magnus underlies cortical hyperexcitability and facilitates trigeminal nociception in a rat model of medication overuse headache

BACKGROUND

The pathogenesis of medication overuse headache (MOH) involves hyperexcitability of cortical and trigeminal neurons. Derangement of the brainstem modulating system, especially raphe nuclei may contribute to this hyperexcitability. The present study aimed to investigate the involvement of the nucleus raphe magnus (NRM) in the development of cortical and trigeminal hyperexcitability in a rat model of MOH.

RESULTS

Chronic treatment with acetaminophen increased the frequency of cortical spreading depression (CSD) and the number of c-Fos-immunoreactive (Fos-IR) neurons in the trigeminal nucleus caudalis (TNC). In the control group, muscimol microinjected into the NRM increased significantly the frequency of CSD-evoked direct current shift and Fos-IR neurons in the TNC. This facilitating effect was not found in rats with chronic acetaminophen exposure. In a model of migraine induced by intravenous systemic infusion of nitroglycerin (NTG), rats with chronic exposure to acetaminophen exhibited significantly more frequent neuronal firing in the TNC and greater Fos-IR than those without the acetaminophen treatment. Muscimol microinjection increased neuronal firing in the TNC in control rats, but not in acetaminophen-treated rats. The number of Fos-IR cells in TNC was not changed significantly.

CONCLUSION

Chronic exposure to acetaminophen alters the function of the NRM contributing to cortical hyperexcitability and facilitating trigeminal nociception.

The need for new acutely acting antimigraine drugs: moving safely outside acute medication overuse

Background

The treatment of migraine is impeded by several difficulties, among which insufficient headache relief, side effects, and risk for developing medication overuse headache (MOH). Thus, new acutely acting antimigraine drugs are currently being developed, among which the small molecule CGRP receptor antagonists, gepants, and the 5-HT_1F receptor agonist lasmiditan. Whether treatment with these drugs carries the same risk for developing MOH is currently unknown.

Main body

Pathophysiological studies on MOH in animal models have suggested that decreased 5-hydroxytryptamine (5-HT, serotonin) levels, increased calcitonin-gene related peptide (CGRP) expression and changes in 5-HT receptor expression (lower 5-HT_1B/D and higher 5-HT_2A expression) may be involved in MOH. The decreased 5-HT may increase cortical spreading depression frequency and induce central sensitization in the cerebral cortex and caudal nucleus of the trigeminal tract. Additionally, low concentrations of 5-HT, a feature often observed in MOH patients, could increase CGRP expression. This provides a possible link between the pathways of 5-HT and CGRP, targets of lasmiditan and gepants, respectively. Since lasmiditan is a 5-HT_1F receptor agonist and gepants are CGRP receptor antagonists, they could have different risks for developing MOH because of the different (over) compensation mechanisms following prolonged agonist versus antagonist treatment.

Conclusion

The acute treatment of migraine will certainly improve with the advent of two novel classes of drugs, i.e., the 5-HT_1F receptor agonists (lasmiditan) and the small molecule CGRP receptor antagonists (gepants). Data on the effects of 5-HT_1F receptor agonism in relation to MOH, as well as the effects of chronic CGRP receptor blockade, are awaited with interest.

Chronic Headache Due to Overuse of Analgesics and Anti-Migraine Agents

BACKGROUND

The frequent or regular use of analgesics and anti-migraine drugs can make headache more frequent and induce the transformation of episodic to chronic headache. Chronic headache due to medication overuse is defined as headache that is present on ≥ 15 days per month for at least three months in a patient who previously suffered from primary headaches, and who takes analgesics on ≥ 15 days per month or anti-migraine drugs (triptans or ergot alkaloids), opioid drugs, or combined analgesics on ≥ 10 days per month.

METHODS

This review is based on pertinent articles published up to December 2017 that were retrieved by a selective search in PubMed employing the terms "medication overuse AND headache" and "medication overuse headache."

RESULTS

The prevalence of medication overuse headache in the general population in Germany is 0.7% -1%. This disorder is more common in women and in persons suffering from comorbid mental disorders or other painful conditions. The treatment of medication overuse headache consists of three steps. Patient education and counseling are given with the goal of reducing the intake of medication for acute headache treatment. The ensuing headache prophylaxis is with topiramate, amitriptyline, or onabotulinum toxin A. If these treatment strategies fail, a drug holiday is recommended. This can be in the outpatient, day clinic, or inpatient setting, depending on the severity of the condition and its comorbidities.

CONCLUSION

Patients who frequently take acute medication to treat headache episodes must be identified early in order to avoid headache chronification and medication overuse headache. The suggested treatment algorithm is still in need of validation by randomized trials.

A systematic review and critical appraisal of gene polymorphism association studies in medication-overuse headache

Purpose of review

Medication-overuse headache is a secondary chronic headache disorder, evolving from an episodic primary headache type, caused by the frequent and excessive use of headache symptomatic drugs. While gene polymorphisms have been deeply investigated as susceptibility factors for migraine, little attention has been paid to medication-overuse headache genetics. In the present study we conducted a systematic review to identify, appraise and summarize the current findings of gene polymorphism association studies in medication-overuse headache.

Methods

A comprehensive literature search was conducted on PubMed and Web of Knowledge databases of primary studies that met the diagnostic criteria for medication-overuse headache according to the temporally-relevant Classification of Headache Disorder of the International Headache Society.

Results

A total of 17 candidate gene association studies focusing on medication-overuse headache were finally included in the qualitative review. Among these, 12 studies investigated the role of common gene polymorphisms as risk factors for medication-overuse headache susceptibility, six studies focused on the relationship with clinical features of medication-overuse headache patients, and four studies evaluated their role as determinants of clinical outcomes in medication-overuse headache patients.

Conclusion

Results of single studies show a potential role of polymorphic variants of the dopaminergic gene system or of other genes related to drug-dependence pathways as susceptibility factors for disease or as determinants of monthly drug consumption, respectively. In this systematic review, we summarize the findings of gene polymorphism association studies in medication-overuse headache and discuss the methodological issues that need to be addressed in the design of future studies.

Rizatriptan overuse promotes hyperalgesia induced by dural inflammatory stimulation in rats by modulation of the serotonin system

Clinical and preclinical studies have implicated serotonin (5-HT) and the 5-HT2A receptor (5-HT2AR) in the pathogenesis of medication-overuse headache (MOH). However, with no appropriate animal model to study this phenomenon it is difficult to differentiate the effects of chronic exposure to analgesics from the consequences of frequent headache attacks during the development of MOH. Therefore, this study used a novel animal model of MOH established by a combination of the overuse of rizatriptan (RIZ) and stimulation with dural inflammatory soup (IS) to investigate whether 5-HT and 5-HT2AR are involved in central plasticity and hyperalgesia. Similar to an IS infusion, IS-RIZ treatment induced nociception-related behaviours in Sprague-Dawley rats and increased Fos expression in the cortex and trigeminal pathway, whereas the RIZ injection alone did not. In addition, overuse of RIZ, administration of an IS stimulus, and a combination of these treatments, decreased the periorbital withdrawal threshold, with IS-RIZ treatment having the most significant effects. Both chronic RIZ exposure and recurring nociception decreased 5-HT expression, whereas IS-RIZ treatment led to decreased expression of 5-HT and upregulation of 5-HT2AR, which was positively correlated with Fos activation. These findings suggest that overuse of RIZ does not directly induce pain via the activation of nociceptive pathways but may increase hyperalgesia by influencing the pain modulation system. Furthermore, decreased 5-HT levels and upregulation of 5-HT2AR may play important roles in this system. Taken together, these findings indicate that medication overuse and frequent headache attacks can promote the neural plasticity associated with MOH.

Medication overuse headache

Medication overuse headache (MOH) is a common and disabling headache disorder. It has a prevalence of about 1-2 % in the general population. The International Classification of Headache Disorders 3rd edition (beta version) has defined MOH as a chronic headache disorder in which the headache occurs on 15 or more days per month due to regular overuse of medication. These headaches must have been present for more than 3 months. The pathophysiology is complex and not completely known. It involves genetic and behavioural factors. There is evidence that cortical spreading depression, trigeminovascular system and neurotransmitters contribute to the pain pathway of MOH. The treatment of MOH includes patient education, stopping the offending drug(s), rescue therapy for withdrawal symptoms and preventative therapy. Relapse rates for MOH are high at 41 %. MOH can severely impact quality of life, so it is important to identify patients who are at risk of analgesic overuse.

Medication-overuse headache: a review

Medication-overuse headache (MOH) is a worldwide health problem with a prevalence of 1%–2%. It is a severe form of headache where the patients often have a long history of headache and of unsuccessful treatments. MOH is characterized by chronic headache and overuse of different headache medications. Through the years, withdrawal of the overused medication has been recognized as the treatment of choice. However, currently, there is no clear consensus regarding the optimal strategy for management of MOH. Treatment approaches are based on expert opinion rather than scientific evidence. This review focuses on aspects of epidemiology, diagnosis, pathogenesis, prevention, and treatment of MOH. We suggest that information and education about the risk of MOH is important since the condition is preventable. Most patients experience reduction of headache days and intensity after successful treatment. The first step in the treatment of MOH should be carried out in primary care and focus primarily on withdrawal, leaving prophylactic medication to those who do not manage primary detoxification. For most patients, a general practitioner can perform the follow-up after detoxification. More complicated cases should be referred to neurologists and headache clinics. Patients suffering with MOH have much to gain by an earlier treatment-focused approach, since the condition is both preventable and treatable.

Medication-overuse headache: epidemiology, diagnosis and treatment

Medication-overuse headache (MOH) is one of the most common chronic headache disorders and a public health problem with a worldwide prevalence of 1-2%. It is a condition characterized by chronic headache and overuse of different headache medications, and withdrawal of the overused medication is recognised as the treatment of choice. However, the strategy for achieving withdrawal is, at present, based on expert opinion rather than scientific evidence, partly due to the lack of randomised controlled studies. This narrative review investigates different aspects of epidemiology, diagnosis, risk factors and pathogenesis as well as management for MOH. We suggest that the first step in the treatment of MOH should be carried out in general practice and should focus primarily on detoxification. For most patients, both prevention and follow up after detoxification can also be performed in general practice, thus freeing resources for referral of more complicated cases to headache clinics and neurologists. These suffering patients have much to gain by an earlier treatment-focused approach lower down on the treatment ladder.

Headache as a presenting feature in patients with serotonin syndrome: a case series

INTRODUCTION

Serotonin syndrome (SS) is a drug-induced constellation of various clinical features that result from excess central serotonergic tone. The clinical features range from barely perceptible to life-threatening conditions.

CASES

We describe four patients with acute headache (four days to three weeks) who were receiving serotonergic drugs for other indications. There was a temporal relation between the administration of the serotonergic drugs and the development of the headaches. All four patients fulfilled the Hunter Serotonin Toxicity Criteria for SS. In parallel, two patients fulfilled the Sternbach's criteria for SS. Discontinuation of the serotonergic drugs and the administration of cyprohepatadine led to complete improvement in three to seven days in all four patients.

DISCUSSION

A review of the literature suggests that some overlaps exist in the pathophysiology between SS and headache disorders, including medication-overuse headache. The overlap is also in the management. The drugs found to be effective in SS (cyproheptadine, chlorpromazine, olanzapine, etc.) are also known to have positive effects on some headache disorders.

CONCLUSION

Physicians should consider the diagnosis of SS in patients with new onset or worsening headache after the addition of serotonergic drugs, especially in the presence of objective signs on examination suggestive of the disorder such as tremor, fever, hyperreflexia, diaphoresis or tachycardia.

Medication-overuse headache

PURPOSE OF REVIEW

Medication-overuse headache (MOH) is a well described clinical entity. There is a growing body of knowledge on the epidemiology of MOH, risk factors, and treatment strategies.

RECENT FINDINGS

The International Headache Society updated the classification criteria for MOH. Population-based studies provided an insight into the prevalence and peculiarities of MOH patients in eastern Europe and Asia. Large-scaled population-based longitudinal studies made it possible to analyze risk factors leading to the development of MOH. Imaging studies helped to better understand the pathophysiology of headache chronicity. New treatment strategies have been suggested.

SUMMARY

MOH is a common headache disorder and a serious public health problem all over the world. Although the treatment regimen for MOH patients is straightforward and the outcomes are favorable, it is time now to move forward and establish a predictive model for early recognition of patients at high risk, to intervene early and avoid development of chronic headache.

Comprehensive RNA-Seq expression analysis of sensory ganglia with a focus on ion channels and GPCRs in Trigeminal ganglia

The specific functions of sensory systems depend on the tissue-specific expression of genes that code for molecular sensor proteins that are necessary for stimulus detection and membrane signaling. Using the Next Generation Sequencing technique (RNA-Seq), we analyzed the complete transcriptome of the trigeminal ganglia (TG) and dorsal root ganglia (DRG) of adult mice. Focusing on genes with an expression level higher than 1 FPKM (fragments per kilobase of transcript per million mapped reads), we detected the expression of 12984 genes in the TG and 13195 in the DRG. To analyze the specific gene expression patterns of the peripheral neuronal tissues, we compared their gene expression profiles with that of the liver, brain, olfactory epithelium, and skeletal muscle. The transcriptome data of the TG and DRG were scanned for virtually all known G-protein-coupled receptors (GPCRs) as well as for ion channels. The expression profile was ranked with regard to the level and specificity for the TG. In total, we detected 106 non-olfactory GPCRs and 33 ion channels that had not been previously described as expressed in the TG. To validate the RNA-Seq data, in situ hybridization experiments were performed for several of the newly detected transcripts. To identify differences in expression profiles between the sensory ganglia, the RNA-Seq data of the TG and DRG were compared. Among the differentially expressed genes (> 1 FPKM), 65 and 117 were expressed at least 10-fold higher in the TG and DRG, respectively. Our transcriptome analysis allows a comprehensive overview of all ion channels and G protein-coupled receptors that are expressed in trigeminal ganglia and provides additional approaches for the investigation of trigeminal sensing as well as for the physiological and pathophysiological mechanisms of pain.

Pathophysiology of medication overuse headache--an update

The pathogenesis of medication overuse headache is unclear. Clinical and preclinical studies have consistently demonstrated increased excitability of neurons in the cerebral cortex and trigeminal system after medication overuse. Cortical hyperexcitability may facilitate the development of cortical spreading depression, while increased excitability of trigeminal neurons may facilitate the process of peripheral and central sensitization. These changes may be secondary to the derangement of central, probably serotonin (5-HT)-, and perhaps endocannabinoid-dependent or other, modulating systems. Increased expression of excitatory cortical 5-HT2A receptors may increase the susceptibility to developing cortical spreading depression, an analog of migraine aura. A reduction of diffuse noxious inhibitory controls may facilitate the process of central sensitization, activate the nociceptive facilitating system, or promote similar molecular mechanisms to those involved in kindling. Low 5-HT levels also increase the expression and release of calcitonin gene-related peptide from the trigeminal ganglion and sensitize trigeminal nociceptors. Thus, derangement of central modulation of the trigeminal system as a result of chronic medication use may increase sensitivity to pain perception and foster or reinforce medication overuse headache.

Factors associated with a negative outcome of medication-overuse headache: A 3-year follow-up (the ‘CARE’ protocol)

Aim

To evaluate factors associated with a negative outcome in a 3-year follow-up of subjects diagnosed with medication-overuse headache (MOH) (revised-ICHD-II criteria).

Methods

All consecutive patients entering the center’s inpatient detoxification program were analyzed in a prospective, non-randomized fashion. All participants were assessed by a neurologist using an ad hoc patient record form. Personality was assessed using the Minnesota Multiphasic Personality Inventory (MMPI)-2, Chi-square test, one-way analysis of variance (ANOVA), and odds ratios (OR) were calculated as appropriate.

Results

One-hundred and fifty patients completed the follow-up (79.3% females, age 46.40 ± 11.31 years): 13 never stopped their drug overuse (A), 38 stopped their overuse, but relapsed at least once (B), and 99 stopped and never relapsed (C). The Group A patients differed from those in B + C as they were more frequently single (OR 0.134; p = 0.007) and unemployed (OR 3.273; p = 0.04), took a higher number of drug doses ( p < 0.001), and less frequently drank coffee (OR 3.273; p = 0.044). Personality profile: subjects in A scored higher than those in C on the following scales: Hypochondriasis ( p = 0.007), Depression ( p = 0.003), Paranoia ( p = 0.025), Fears ( p = 0.003), Obsessiveness ( p = 0.026), Bizarre Mentation ( p = 0.046), Social Discomfort ( p = 0.004), Negative Treatment Indicators ( p = 0.040), Repression ( p = 0.007), Overcontrolled Hostility ( p = 0.040), Addiction Admission ( p = 0.021), Social Responsibility ( p = 0.039), and Marital Distress ( p = 0.028).

Conclusion

Disease outcome in MOH patients is influenced negatively by overuse severity and by specific psychological and socio-economic variables. Other possible modifier factors were voluptuary habits.

Prevalence of medication overuse headache in an interdisciplinary pain clinic

Background

Medication overuse headache (MOH) has been recognized as an important problem in headache patients although the pathophysiological mechanisms remain unclear. The diagnosis of MOH is based on clinical characteristics defined by the International Headache Society. The aim was the evaluation of the diagnostic criteria of MOH in a mixed population of chronic pain patients to gain information about the prevalence and possible associations with MOH.

Methods

Data of all patients referred to the interdisciplinary pain clinic at the University Hospital of Zurich between September 2005 and December 2007 were retrospectively analyzed. Demographic data (age, sex, history of migration), as well as data about duration of pain disease, category of pain disease (neurological, psychiatric, rheumatologic, other), use of medication, history of trauma, and comorbidity of depression and anxiety have been collected.

Results

Totally 178 of 187 consecutive chronic pain patients were included in the study. A total of 138 patients (78%) used analgesics on 15 or more days per month. Chronic headache was more prevalent among patients with analgesic overuse (39.8%) than without analgesic overuse (18%). The prevalence of MOH was 29%. The odds ratio (OR) for a patient with medication overuse to have chronic headache was 13.1 if he had a history of primary headache, compared to a patient without a primary headache syndrome. Furthermore, history of headache (OR 2.5, CI [1.13;5.44]), history of migration (OR 2.9, CI [1.31;6.32]) and comorbid depression (OR 3.5, CI [1.46;8.52]) were associated with overuse of acute medication, in general.

Conclusions

Primary headaches have a high risk for chronification in patients overusing analgesics for other pain disorders. Whereas history of headache, history of migration and comorbidity of depression are independentely associated with analgesic overuse in this group of patients.

Medication-overuse headache and opioid-induced hyperalgesia: A review of mechanisms, a neuroimmune hypothesis and a novel approach to treatment

Introduction

Patients with chronic headache who consume large amounts of analgesics are often encountered in clinical practice. Excessive intake of analgesics is now considered to be a cause, rather than simply a consequence, of frequent headaches, and as such the diagnosis “medication-overuse headache” (MOH) has been formulated. Despite the prevalence and clinical impact of MOH, the pathophysiology behind this disorder remains unclear and specific mechanism-based treatment options are lacking.

Discussion

Although most acute headache treatments have been alleged to cause MOH, here we conclude from the literature that opioids are a particularly problematic drug class consistently associated with worsening headache. MOH may not be a single entity, as each class of drug implicated may cause MOH via a different mechanism. Recent evidence indicates that chronic opioid administration may exacerbate pain in the long term by activating toll-like receptor-4 on glial cells, resulting in a pro-inflammatory state that manifests clinically as increased pain. Thus, from the available evidence it seems opioid-overuse headache is a phenomenon similar to opioid-induced hyperalgesia, which derives from a cumulative interaction between central sensitisation, due to repeated activation of nociceptive pathways by recurrent headaches, and pain facilitation due to glial activation.

Conclusion

Treatment strategies directed at inhibiting glial activation may be of benefit alongside medication withdrawal in the management of MOH.

Habituation to pain in "medication overuse headache": a CO2 laser-evoked potential study

OBJECTIVE

Our aim was to investigate CO(2) laser-evoked potential (LEP) habituation to experimental pain in a group of patients affected by medication-overuse headache, with a history of episodic migraine becoming chronic, before and after treatment, consisting in acute medication withdrawal and a preventive treatment cycle.

BACKGROUND

One of the main features of LEPs in migraineurs is a lower habituation to repetitive noxious stimuli during the interictal phase.

METHODS

LEPs were recorded to stimulation of both the right hand and the right perioral region in 14 patients and in 14 healthy subjects. The habituation of both the N1 and the vertex N2/P2 components was assessed by measuring the LEP amplitude changes across 3 consecutive repetitions of 30 trials each.

RESULTS

In the 8 patients who had clinically improved after treatment, the N2/P2 amplitude habituation was significantly higher after treatment than before treatment following both hand (F = 43.2, P < .0001) and face stimulation (F = 6.9, P = .01). In these patients, the N2/P2 amplitude habituation after treatment was not different from that obtained in healthy controls (P = .18 and P = .73 for hand and face stimulation, respectively). On the contrary, in the patients who did not improve, the N2/P2 amplitude still showed reduced habituation after both hand (F = 3.1, P = .08) and face (F = 0.7, P = .4) stimulation.

CONCLUSION

The deficient habituation of the vertex N2/P2 complex was partly restored after successful treatment of medication-overuse headache, reflecting a modification in pain-processing pathways.

Chronic migraine with medication overuse pre-post withdrawal of symptomatic medication: clinical results and FMRI correlations

BACKGROUND

Chronic migraine with symptomatic medication overuse (CMwMO) is a common and often debilitating clinical condition. Withdrawal of the offending drug(s) is considered the first step in management. Functional magnetic resonance imaging (fMRI) may be a useful technique for obtaining information on particular neuronal changes in the pain network involved in this condition.

OBJECTIVE

To identify specific fMRI patterns in patients suffering from CMwMO before and after withdrawal intervention.

METHODS

We collected fMRI data from a group of patients suffering from CMwMO, evaluating those patients prior to and 6 months following withdrawal. We applied stimuli at sites far removed from where the headaches were experienced. Moreover, pre-intervention fMRI data from the headache patients were compared with those obtained from headache-free and otherwise healthy controls.

RESULTS

Before withdrawal, the right supramarginal gyrus, the right inferior and superior parietal cortex were hypoactive. Activity recovered to almost normal 6 months after withdrawal of the offending medications.

CONCLUSIONS

The hypoactivation we detected in the lateral pain system indicate that there exists a modification of the pain network in CMwMO and that these changes are reversible with therapy.

Epidemiology, risk factors, and treatment of chronic migraine: a focus on topiramate

The term chronic daily headache refers to a heterogeneous group of headache disorders characterized by a frequency of headaches on > or = 15 days per month. Chronic migraine is a subtype of chronic daily headache. The prevalence of chronic migraine is approximately 1%. Baseline attack frequency and acute medication overuse have been identified as potential risk factors for the progression of migraine from an episodic disorder to a chronic condition. There is an unmet patient need for effective and safe treatments for patients with chronic migraine, but data from rigorous controlled trials are limited. Previous studies have demonstrated that topiramate is an effective and safe preventive treatment for episodic migraine. In addition, pilot studies have suggested the utility of topiramate for the prevention of chronic migraine. Two randomized, double-blind, placebo-controlled, multicenter trials investigating the efficacy and safety of topiramate in the treatment of patients with chronic migraine have recently been completed. This review presents comparative data from these 2 clinical trials, which suggest that topiramate at a dose of 100 mg daily is effective and generally well tolerated in chronic migraine.

The effects of chronic administration of sumatriptan and dipyrone on serotonergic system in the rat brain: an immunohistochemical study

OBJECTIVE

To investigate the effects of chronic high dose sumatriptan and dipyrone treatment on central serotonergic system in rats.

MATERIALS AND METHODS

Male Sprague-Dawley rats (seven per group) were daily injected with sumatriptan (3 mg/kg), dipyrone (400 mg/kg) or saline for 30 days. The brains of animals were surgically removed and immunohistochemically stained for serotonin. Serotonin-positive stained cells were counted automatically by using a computerized image analysis program. Statistical analysis carried out using one-way ANOVA followed by post hoc Tukey test.

RESULTS

A significant decrease in serotonin-positive cells in the brainstem was observed after chronic sumatriptan administration while chronic use of dipyrone induced a significant increase in serotonin-positive cells both in the cortex and midbrain.

CONCLUSION

Our data suggest that central serotonergic system might be modified by chronic use of sumatriptan and dipyrone.

Medication-overuse headache: where are we now?

PURPOSE OF REVIEW

Many important studies on medication-overuse headache have been published in the last year. Some of them investigated the pathophysiology of headache chronicity, others focused on evaluation of risk factors. The International Headache Society revised the classification criteria. We provide a summary of the new findings and concepts.

RECENT FINDINGS

Medication-overuse headache was previously defined by the International Headache Society as a chronic headache which occurs following overuse of headache drugs and improves after withdrawal. Hence, the improvement of headache after withdrawal was mandatory for diagnosis. The new appendix criteria appeared last year and established a broader concept of medication-overuse headache no longer requiring improvement after discontinuation of medication overuse. Several large population-based longitudinal studies clearly demonstrated that overuse of any kind of acute headache medication is the main risk factor leading to development of chronic headache. Imaging studies provided new important insights into the pathophysiology of headache chronicity. New treatment strategies have been suggested.

SUMMARY

Recent data provide better insight into pathophysiology of medication-overuse headache. Epidemiological studies clearly demonstrate the necessity of establishing a predictive model for early recognition of patients at high risk to intervene early and avoid development of chronic headache.

Serotonin Depletion, Cortical Spreading Depression, and Trigeminal Nociception

BACKGROUND

The attack of migraine has been observed to be associated with low level of serotonin (5-HT). Although the mechanism underlying this relationship is still unclear, change in cortical excitability or susceptibility of trigeminal system is a possible explanation.

OBJECTIVES

The aim was to study the effect of 5-HT depletion on the development of cortical spreading depression (CSD) and CSD-evoked trigeminal nociception.

METHODS

Wistar rats were separated into low 5-HT and control groups (eight rats each). 5-HT was depleted by administration of para-chlorophenylalanine, a tryptophan hydroxylase inhibitor. CSD was induced by applying 3 mg of potassium chloride on parietal cortex. Cortical activity was monitored for 1 hour. Trigeminal nociception was determined using number of Fos-immunoreactive (Fos-IR) neurons in trigeminal nucleus caudalis as the indicator.

RESULTS

Application of KCl led to the development of series of depolarization shift characteristics for CSD. The development of these CSD waves was enhanced in low 5-HT state. The area under curve of each CSD wave and the number of CSD waves occurring within 1 hour were greater in low 5-HT group. No significant change in peak amplitude and duration of CSD wave was observed. The numbers of Fos-IR cells on ipsilateral and contralateral trigeminal nucleus caudalis were significantly greater in the low 5-HT group than those of the controls.

CONCLUSION

Our findings indicate that 5-HT depletion enhances CSD-induced trigeminal nociception by increasing the cortical excitability and sensitivity of trigeminal nociceptive system. These findings may provide a better understanding regarding the relationship between low 5-HT and clinical headaches.

Medication-overuse headache: similarities with drug addiction

Medication-overuse headache (MOH) is a clinically important entity and it is now well documented that the regular use of acute symptomatic medication by people with migraine or tension-type headache increases the risk of aggravation of the primary headache. MOH is one the most common causes of chronic migraine-like syndrome. In this article, we analyse the possible mechanisms that underlie sensitization in MOH by comparing these mechanisms with those reported for other forms of drug addiction. Moreover, the evidence for cognitive impulsivity in drug overuse in headache and in other forms of addiction associated with dysfunction of the frontostriatal system will be discussed. An integrative hypothesis for compulsive reward-seeking in MOH will be presented.

Overuse of symptomatic medications among chronic (transformed) migraine patients: profile of drug consumption

Chronic daily headache and chronic (transformed) migraine (TM) patients represent more than one third of the subjects seen in specialized headache centers. Most of these patients may overuse symptomatic medications (SM) taken on a daily basis to relieve headache and associated symptoms. The conversion to the daily or near-daily pattern of headache presentation is thought to be related to the medication overuse. The aim of this study was to evaluate the profile of SM consumption among transformed migraine patients attending a tertiary center. One hundred thirty three consecutive patients (22 men and 111 women, ages 17 to 80) with TM and overuse of SM according to the proposed criteria of Silberstein et al (1994, 1996) were prospectively studied. None of the patients were under treatment for other conditions. Among them, 73 (54.9%) were using one category of SM, while 55 (41.3%) and 5 (3.8%) patients were taking simultaneously two and three categories of SM respectively. The categories of overused symptomatic medications varied from simple analgesics to narcotics, triptans and combinations of ergot derivatives and caffeine and of analgesics and caffeine. The average intake per patient per day was of 3 to 4 tablets and mostly of the patients overused simple analgesics (isolated or in combination with other substances) (75.2%), caffeine containing drugs (71.4%), drugs containing ergotamine derivatives (26.1%), triptans (alone or combined) (15.5%), drugs with narcotics or ansiolitics (13%) and anti-inflammatory drugs (3.7%). The mechanisms by which the overuse of symptomatic medications may play a role in this transformation are uncertain but despite of the necessity of controlled trials to demonstrate the real role of such compounds in the development of transformed migraine, this study emphasizes the necessity for more rigorous prescribing guidelines for patients with frequent headaches.

Platelet serotonin measures in migraine

OBJECTIVE AND BACKGROUND

Serotonergic mechanisms play an important role in the pathogenesis of headache. To search for potential indicators of altered serotonin homeostasis in migraine, we have investigated three parameters of the platelet serotonin (5HT) system, platelet serotonin level (PSL), platelet serotonin uptake (PSU), and monoamine oxidase (MAO-B) activity, in a group of 55 patients with migraine and in 81 healthy controls.

METHODS

After platelet separation, PSL was determined fluorimetrically; PSU was measured by incubating aliquots of platelet-rich plasma with six concentrations of 14C-5-HT for 60 seconds at 37 degrees C, followed by vacuum filtration; platelet MAO-B activity (toward kynuramine as a substrate) was determined fluorimetrically.

RESULTS

Values of the investigated measures, in patients versus controls, amounted to (mean +/- SD) 608 +/- 166 vs. 591 +/- 184 ng/10(9) platelets for PSL, 139 +/- 25 vs. 142 +/- 25 pmol 5HT/10(8) platelets/minute for Vmax of PSU, 376 +/- 62 vs. 404 +/- 72 nM for Km of PSU, and 15.8 +/- 5.1 vs. 14.3 +/- 5.7 nmol product/10(8) platelets/60 minutes for velocity of MAO-B. Mentioned parameters did not show statistical differences between patients and controls, with exception of a small difference in Km of PSU, reaching significance (P<0.01). After subgrouping of patients according to diagnosis (migraine with aura, migraine without aura, and migraine attack) and gender, no differences retained significance.

CONCLUSIONS

Our results indicate the absence of a measurable disturbance in 5HT homeostasis in migraine, as shown by platelet 5HT parameters, and they question the suitability of the use of mentioned blood elements in this regard.

2002 Wolff Award. 5 -HT2A receptor activation and nitric oxide synthesis: a possible mechanism determining migraine attacks

OBJECTIVE

To determine the effect of the 5-HT2A receptor in control of spinal nociception, cerebral circulation, and nitric oxide synthase (nNOS) expression in trigeminovascular neurons.

BACKGROUND

The plasticity of the 5-HT2A receptor is a possible factor determining the course of migraine. Up-regulation of this receptor has been demonstrated to correlate with the increasing frequency of migraine attacks and may underlie the development of chronic daily headache.

METHODS

Adult male Wistar rats were divided into groups receiving the 5-HT2A agonist, 1,2,5-dimethoxy-4-iodophenyl-2-aminopropane (DOI), nitroglycerin, or normal saline. The tail flick test and chemical nociception-evoked Fos-expression in dorsal horn neurons were used as indicators of nociception. Regional cerebral blood flow was monitored using laser Doppler flowmetry. Expression of Fos and nNOS was studied using immunohistochemical method.

RESULTS

Administration of DOI led to the shortening of tail flick latency (1.3 +/- 0.2 and 7.2 +/- 0.6 seconds for DOI-treated and control groups, respectively). The number of Fos-immunoreactive neurons was also greater in the DOI-treated group compared with the control group. DOI also produced long-lasting cerebral hyperemia (123% of baseline value) associated with the enlargement of perivascular nNOS-immunoreactive nerve fibers and increased nNOS-immunoreactive neurons in trigeminal ganglia and trigeminal nucleus caudalis. These findings resembled those observed in the rats exposed to nitroglycerin.

CONCLUSION

Our results suggest that activation of the 5-HT2A receptor leads to an enhancement of NO production in trigeminovascular pathway. NO may trigger migraine attacks by inducing cerebral vasodilation and sensitizing the perivascular nociceptors and central nociceptive neurons in trigeminovascular system. Up-regulation of this pronociceptive receptor can increase headache attacks and contributes to the development of chronic daily headache.

Pathophysiology of chronic daily headache

Despite no clear explanation of the mechanism underlying chronic daily headache, sensitization of central nociceptive neurons is one possibility. Either prolonged activation of peripheral nociceptors or any factors that can alter the endogenous pain control system can trigger this process. A decrease in platelet serotonin has been observed in patients with chronic tension-type headache as well as migraine patients with medication-induced headache. It was also shown that chronic analgesic exposure led to changes in the serotonin content and the density of the 5-HT(2A) receptor in the cerebral cortex. The plasticity of the serotonin-dependent pain control system may facilitate the process of sensitization and results in the development of chronic daily headache.

Platelet 3H ketanserin binding in migraine

Platelet 3H ketanserin binding was studied in 33 patients of migraine and 30 healthy controls. The binding characteristics: equilibrium dissociation constant (Kd) and maximal number of binding sites (Bmax) determined by Scatchard analysis revealed a significant decrease in Kd and no change in Bmax in migraine cases. No correlation was observed between the Kd and Bmax with the clinical features of migraine. The findings of the present study show that there is a decreased affinity of platelet 5-HT2 receptors in migraine.

Successful withdrawal from analgesic abuse in a group of youngsters with chronic daily headache

Abuse of ergotamine and analgesics is common in adults. It coexists with headache and can also induce headaches. Ten to 15% of patients attending headache clinics and 1% of the general population suffer from chronic daily headache due to medication misuse. Indeed, this phenomenon was recently regarded as an epidemic. Nonetheless, analgesic-induced headache in children and adolescents was first reported in 1998. We report on our experience with children and adolescents with daily or almost-daily headache concomitant with daily or almost-daily analgesic intake. Over a period of 3 years, we evaluated 26 children (19 girls and 7 boys) with chronic daily or near-daily headache related to daily analgesic intake. The mean age of the group was 14.2 years (range, 12-18), and the mean headache history duration was 1.6 years (range, 3 months to 4 1/2 years). The mean number of headache days per month was 28.1 (range, 19-31). All patients had no history of migraine prior to the chronic headache phase according to the International Headache Society criteria. They were using at least one dose of analgesic drug for each headache, whereas 16 were using analgesic drugs daily. The weekly analgesic intake averaged 28.1 tablets (range, 19-41). The majority abused simple analgesics. Twenty-one took acetaminophen alone. Five took a combination; four took a compound containing acetaminophen, caffeine, and codeine; and the fifth patient took a compound containing aspirin, caffeine, and codeine. All patients were informed about the phenomenon of medication-induced headache and were encouraged to achieve drug withdrawal. Withdrawal led to complete cessation of all headaches in 20 patients. In 5 patients, the daily headache resolved; however, they suffered from intermittent episodic migraine attacks, which were frequent enough in 3 to initiate prophylactic medication. One adolescent continued to have daily headache. Analgesic-induced headache does occur in adolescents. Successful withdrawal from the offending analgesics was achieved without hospitalization or significant interference with daily life and with complete disappearance of the induced chronic daily headache in 25 of 26 patients.

Opiate use to control bowel motility may induce chronic daily headache in patients with migraine

OBJECTIVES

To investigate whether opiate overuse might cause chronic daily headache in those with migraine, we studied patients who were taking codeine (or other opiates) for control of bowel motility after colectomy for ulcerative colitis.

BACKGROUND

Analgesic overuse is considered by many to be one factor which can result in the transformation of migraine into a chronic daily headache pattern. Most of the evidence for this comes from patients with migraine who are taking increasing amounts of analgesia for headache. Many of these patients revert to an intermittent migraine pattern once the analgesics are stopped.

METHODS

Women who were 1 year postcolectomy for ulcerative colitis were identified in several colorectal surgery practices in Calgary. They were sent a questionnaire designed to determine if they had a history of migraine prior to surgery, if they currently had chronic daily headache, what medications they were taking to control bowel motility, and what medications they were taking for headache.

RESULTS

Twenty-eight patients who met our inclusion criteria returned completed questionnaires. Eight of these exceeded the recommended limits for opiate use in patients with headache. Eight patients met diagnostic criteria for migraine. Two patients had chronic daily headache starting after surgery. Both used daily opiates beginning after their surgery, and both had a history of migraine. The other six patients who used opiates daily did not have a history of migraine and did not have chronic daily headache. All patients with migraine who used daily opiates to control bowel motility following surgery developed chronic daily headache after surgery.

CONCLUSIONS

Patients with migraine who use daily opiates for any reason are at high risk of developing transformed migraine with chronic daily headache. This risk appears much lower in patients without a history of migraine who use opiates for nonpain indications.

Effect of withdrawal of misused medication on sleep disturbances in migraine sufferers with chronic daily headache

OBJECTIVES

To evaluate the sleep pattern of migraineurs with chronic daily headache and to determine whether and to what degree it is improved by withdrawal of medication, and to reconfirm relief of headache by withdrawal of medications in migraineurs with chronic daily headache due to medication misuse.

BACKGROUND

Misuse of ergotamine and analgesics by migraineurs is one of the causes of chronic daily headache. The latter is alleviated or abolished in these patients by abrupt withdrawal of the misused medication. In common with patients with chronic daily headache, migraineurs frequently complain of insomnia, usually verifiable by polysomnography.

METHODS

Twenty-six women with migraine, aged 18 to 49 years, with chronic daily headache due to medication misuse, voluntarily discontinued ergotamine and analgesics, and were followed at monthly intervals for 3 months. In 25 subjects, polysomnography was performed before withdrawal of medication and 3 months after withdrawal. All subjects filled out a standard sleep questionnaire on those two occasions and a daily self-assessment questionnaire focused on headaches.

RESULTS

After 3 months, a significant decrease in mean headache frequency (P<.001) and intensity (P<.001) was demonstrated. Polysomnography performed 3 months after medication withdrawal showed significant improvement in total sleep time (P<.05), sleep efficiency (P<.05), and number of arousals (P<.001). The score of the sleep questionnaire was also significantly improved (P<.01).

CONCLUSIONS

In migraineurs with chronic daily headache due to medication misuse, withdrawal of the misused medications alleviates the associated sleep disturbance along with diminution in frequency and intensity of chronic daily headache.

Effect of chronic analgesic exposure on the central serotonin system: a possible mechanism of analgesic abuse headache

OBJECTIVE

To investigate the effects of chronic analgesic exposure on the central serotonin system and the relationship between the serotonin system and the analgesic efficacy of nonnarcotic analgesics.

METHODS

Paracetamol was administered daily to adult male Wistar rats for a period of 15 or 30 days. Analgesic efficacy was measured by the tail flick test. After completion of the treatment protocol, the rats were humanely killed, and the frontal cortex and brain stem were isolated. Characteristics of the specific binding of the 5-HT2A serotonin receptor and the serotonin transporter were studied using a radioligand binding technique. Platelet serotonin was determined by high-performance liquid chromatography.

RESULTS

Chronic paracetamol administration resulted in a significant decrease in the maximum number of 5-HT2A binding sites and an increase in the maximum number of 5-HT transporter binding sites in frontal cortical membrane (P<.001). Changes in the central 5-HT system were associated with a rise in platelet 5-HT levels. The degree of receptor downregulation, as well as transporter upregulation, became less evident after more prolonged drug administration. Readaptation of serotonin receptors and transporters coincided with the decrease in the analgesic efficacy of paracetamol, as well as a fall in platelet 5-HT levels.

CONCLUSIONS

These findings provide further evidence in support of an involvement of the 5-HT system in the antinociceptive activity of simple nonnarcotic analgesics. Plasticity of this neurotransmitter system after chronic analgesic exposure may lead to the loss of analgesic efficacy and, in its more extreme form, may produce analgesic-related painful conditions, for example, analgesic abuse headache.

Prednisone as initial treatment of analgesic-induced daily headache

The majority of the patients who seek medical care in tertiary headache centres present with transformed migraine, and convert to daily headache, as a result of excessive intake of symptomatic medications (SM). This study aimed to analyse the possibility of using a short course of oral prednisone for detoxifying patients with chronic daily headache due to medication overuse in an out-patient setting. Four hundred patients with headache occurring more than 28 days per month for longer than 6 months were studied (mean baseline frequency of 0.96). Symptomatic medications were stopped suddenly and prednisone was initiated in tapering doses during 6 days, followed by the introduction of preventive treatment. Withdrawal symptoms and the frequency, intensity and duration of the headache, as well as the consumption of rescue medications, were analysed during the first 16 and 30 days of withdrawal. Eighty-five percent of the patients experienced a reduction in headache frequency and no patients presented severe attacks during the first 6 days. With regard to the following 10 days, 46% of the patients experienced at least 2 days without headache and 58% less intense attacks. Most of the patients noticed attacks with longer duration. After the 30-day period there was a significant decrease in headache frequency (mean 0.83, P<0.001), and no patients returned to overuse of SM. This study demonstrates that it is possible to detoxify patients suffering from rebound headaches, using oral prednisone during the first days of withdrawal, in an out-patient setting.