Cortical and Subcortical Alterations in Medication Overuse Headache

Induction of more severe central sensitization in a medication overuse headache model mice through active ingestion of rizatriptan

BACKGROUND

Medication overuse headache (MOH) is a secondary headache disorder arising from excessive use of acute analgesics in patients with primary headache. Current animal models that predominantly employ passive drug administration fail to recapitulate the hallmark feature of voluntary medication-seeking behaviour observed clinically. Therefore, we established a novel MOH mouse model with the active ingestion of rizatriptan (RIZ) to better simulate the clinical characteristics of MOH and explore changes in brain activation patterns.

METHODS

C57BL/6 J mice received intraperitoneal injections of nitroglycerin (NTG, 10 mg/kg) every other day. During the feeding period, they were provided with two bottles-one containing an RIZ solution (0.02 mg/kg) and the other containing deuterium depleted water (DDW)-allowing for voluntary intake. The bottle containing the RIZ solution was marked with a fixed colour indicator at the nozzle. Behavioural assessments included mechanical allodynia (von Frey filaments), anxiety-like behaviours (elevated plus maze, EPM and open field test, OFT), and drug-seeking quantification. Quantitative data from c-Fos immunostaining across 25 specific brain regions were subjected to Z score normalization, followed by three-tiered computational analyses: 1) hierarchical clustering (complete linkage) to characterize activation patterns, 2) Pearson correlation analysis for functional connectivity mapping, and 3) graph-theoretical network analysis (Cytoscape 3.2.1) to identify hub regions and their topological relationships. The small molecule calcitonin gene-related peptide (CGRP) receptor antagonist, rimegepant (100 mg/kg, i.p., 7 injections) was administered during the modelling period, and withdrawal of RIZ and NTG was applied after modelling to observe behavioural and histological changes.

RESULTS

Chronic RIZ consumption exacerbated NTG-induced cutaneous allodynia, prolonged central sensitization, and increased anxiety-like behaviour. Rimegepant attenuated allodynia progression, whereas withdrawal of RIZ and NTG normalized pain thresholds. Network analysis identified the prelimbic cortex (PrL) and spinal trigeminal nucleus caudalis (SPVC) as hub nodes. The PrL exhibited extensive functional connectivity with addiction-related regions (the insular cortex, IC and nucleus accumbens), whereas the SPVC showed predominant connections with pain-processing areas.

CONCLUSION

This study pioneers an ethologically valid MOH model that reflects more severe central sensitization and recapitulates active medication-seeking behaviour. PrL-mediated addiction-like-behaviour pathways and SPVC-centred nociceptive processing may play roles in the development of MOH. These findings provide novel neuromodulation targets (PrL, IC, SPVC) for refractory MOH management.

Neurophysiological Effects of Withdrawal from Acute Overused Medications in Chronic Migraine with Medication-Overuse Headache

Background/Objectives: Chronic migraine with medication-overuse headache (CM-MOH) is neurophysiologically characterized by increased cortical excitability with sensitization at both the thalamocortical and the cortical levels. It is unclear whether the increased cortical excitability could be reverted by medication withdrawal (i.e., brain state) or whether it is a brain trait of individuals predisposed to medication overuse. In this study, we aim to investigate whether withdrawal from overused drugs can influence and restore these neurophysiological abnormalities. Methods: Somatosensory evoked potentials (SSEPs) were elicited by electrical stimulation of the median nerve (M), the ulnar nerve (U), and the simultaneous stimulation of both nerves (MU) in 14 patients with CM-MOH before (T0) and after (T1) a three-week withdrawal protocol and, for comparison, in 14 healthy volunteers (HVs) of a comparable age distribution. We measured the level of thalamocortical (pre-HFO) and cortical activation (post-HFO) by analyzing the high-frequency oscillations (HFOs) embedded in parietal N20 median SSEPs. Furthermore, we calculated the habituation and the degree of cortical lateral inhibition (dLI) of N20-P25 low-frequency SSEPs. Results: After the three-week withdrawal protocol (T1), we observed a normalization of the baseline habituation deficit (T0: +0.10 ± 0.54; T1: -0.53 ± 0.8; p = 0.040) and a reduction in the amplitude for both pre-HFO (p < 0.009) and post-HFO (p = 0.042), with values comparable to those of the HVs. However, no effects were observed on the dLI (p = 0.141). Conclusions: Our findings showed that withdrawal from overused drugs could affect the increased excitability of the non-painful somatosensory system in patients with CM-MOH, reducing the level of sensitization at both the thalamocortical and the cortical levels.

Medication overuse headache associated with decreased dopamine transporter availability in the medial but not in the lateral orbitofrontal cortex: a 11CFT PET/MR study

BACKGROUNDS

Dysfunction of the mesocorticolimbic dopamine system in medication overuse headache (MOH) is unknown. This study aimed to determine dopamine transporter (DAT) availability, which is sensitive to dopamine levels, in the mesocorticolimbic dopamine system in MOH patients.

METHODS

This case-control study investigated eligible MOH patients admitted to the International Headache Centre in the neurological department of Chinese PLA General Hospital between July 2018 and August 2019. All subjects underwent an integrated positron emission tomography (PET)/magnetic resonance (MR) brain scans with 11CFT, a radioligand that binds to DAT. Standardised uptake value ratio (SUVr) images were compared voxelwise between MOH patients and healthy controls (HCs). SUVr values from significantly changed regions were extracted, and partial correlation analyses with clinical measures were conducted.

RESULTS

We examined 17 MOH patients and 16 HCs. MOH patients had lower SUVr levels in the medial rather than lateral orbitofrontal cortex (OFC) than HCs (T = -5.0317, PGRF < 0.01), which showed no correlation with clinical features.

CONCLUSIONS

MOH is characterised by decreased DAT availability in the medial OFC, which might reflect compensatory downregulation due to low dopamine signalling within the mesocorticolimbic dopamine system and provide a new perspective to understand the pathogenesis of MOH.

Cerebellar somatotopy of the trigemino-cervical complex during nociception

INTRODUCTION

The somatotopic organization of the human cerebellum processes somato-motoric input. Its role during pain perception for nociceptive input remains ambiguous. A standardized experimental trigeminal nociceptive input in functional imaging might clarify the role of the cerebellum in trigeminal nociception. Also of interest is the greater occipital nerve, which innervates the back of the head, and can influence the trigeminal perception due to functional coupling within the brainstem, forming the so-called trigemino-cervical complex.

METHODS

In our preregistered study (clinicaltrials.gov: NTC03999060), we stimulated the greater occipital as well as the three main branches of the trigeminal nerve during functional magnetic resonance imaging in two independent cohorts of young healthy volunteers without psychiatric, neurological or pain-related disorders to disentangle overlapping somatotopic cerebellar organization of the nerves innervating the human head.

RESULTS

We found a dominant effect of the first trigeminal branch in the cerebellum, underpinning its particular role for headache diseases, and somatotopic representations in bilateral cerebellar lobules I-IV, V, VIIb, VIIIa and Crus I as well as in the brainstem.

SIGNIFICANCE

The study expands the current knowledge on facial and head pain processing by the cerebellum and provides an initial somatotopic map of the trigemino-cervical complex in the human cerebellum with a predominant representation of the first trigeminal branch.

Medication-Overuse Headache

OBJECTIVE

Medication-overuse headache (MOH) has been described for almost 100 years and is characterized as a daily or near-daily headache that usually presents in patients with preexisting primary headache disorders who are overusing one or more acute or symptomatic headache medications. This article reviews the diagnosis and management of patients with MOH.

LATEST DEVELOPMENTS

The International Classification of Headache Disorders criteria for MOH have changed over time. The worldwide prevalence appears to be between 1% and 2%. Together, headache disorders, including MOH, are currently ranked as the second leading cause of years lived with disability in the Global Burden of Disease world health survey. Significant neurophysiologic changes are seen in the brains of patients with MOH, including functional alterations in central pain processing and modulating systems and central sensitization. Research supports updates to the principles of management, including weaning off the overused medication, preventive therapy, biobehavioral therapy, and patient education.

ESSENTIAL POINTS

MOH is a fairly common and treatable secondary headache disorder that produces significant disability and a substantial reduction in quality of life. The costs related to lost income and disability are substantial. MOH is intimately related to chronic migraine, which continues to be underrecognized and undertreated. Treatment focuses on both the institution of effective preventive migraine therapy and the reduction or removal of the overused medications. Educational efforts directed toward both providers and patients have been shown to be effective in reducing the effect of MOH.

Functional connectivity of the visual cortex in chronic migraine before and after medication withdrawal therapy

Acute withdrawal of headache medication in chronic migraine patients with medication overuse may lead to a dramatic reduction in headache frequency and severity. However, the brain networks underlying chronic migraine and a favorable response to acute withdrawal are still poorly understood. The goal of the present study was to characterize the pattern of intrinsic magnetic resonance imaging (MRI) functional connectivity (FC) specific to chronic migraine and to identify changes in FC that characterize subjects with CM reverting to less frequent headaches. Subjects with chronic migraine (N = 99) underwent a resting-state functional MRI scan before and after three months of medication withdrawal therapy. In addition, we included four control groups who were scanned once: healthy participants (N = 27), patients with episodic migraine (N = 25), patients with chronic back pain (N = 22), and patients with clinical depression (N = 17). Using dual regression analysis, we compared whole-brain voxel-level functional connectivity with ten well-known resting-state networks between chronic migraine and control groups, and between responders to treatment (≥50 % reduction in monthly headache days) and non-responders (<50 % reduction), before and after treatment. Subjects with chronic migraine showed differences in FC with a number of RS-networks, most of which involved the visual cortex, compared with healthy controls. A comparison with patients with episodic migraine, chronic pain and depression showed differences in the same direction, suggesting that altered patterns of functional connectivity in chronic migraine patients could to some extent be explained by shared symptomatology with other pain, depression, or migraine conditions. A comparison between responders and non-responders indicated that effective withdrawal reduced FC with the visual cortex for responders. Interestingly, responders already differed in functional connectivity of the visual cortex at baseline compared with non-responders. Altogether, we show that chronic migraine and successful medication withdrawal therapy are linked to changes in the functional connectivity of the visual cortex. These neuroimaging findings provide new insights into the pathways underlying migraine chronification and its reversibility.

Decision-making impairment under ambiguity but not under risk may underlie medication overuse in patients with chronic migraine

OBJECTIVE

To explore whether patients with chronic migraine and medication overuse headache (CM + MOH) present with decision-making deficit.

BACKGROUND

Factors underlying MOH in patients with CM remain unclear. Whether the process of decision-making plays a role in MOH is still controversial. Decision-making varies in the degree of uncertainty: under ambiguity where the probability of outcome is unknown, and under risk where probabilities are known.

METHODS

Decisions under ambiguity and risk were assessed with the Iowa Gambling Task and the Cambridge Gambling Task, respectively, whereas executive function was assessed by the Wisconsin Card Sorting Test.

RESULTS

A total of 75 participants: 25 patients with CM + MOH, 25 with CM, and 25 age- and sex-similar healthy controls (HCs), completed this cross-sectional study. There was no significant difference in headache profiles except for more frequent analgesic use (mean ± SD: 23.5 ± 7.6 vs. 6.8 ± 3.4 days; p < 0.001) and higher Severity of Dependence Scores (median [25th-75th percentile]: 8 [5-11] vs. 1 [0-4]; p < 0.001) in patients with CM + MOH compared to CM. Total net score (mean ± SD) on the Iowa Gambling Task in patients with CM + MOH, CM, and HCs were - 8.1 ± 28.7, 10.9 ± 29.6, and 14.2 ± 28.8, respectively. There was a significant difference between the three groups (F(2, 72)  = 4.28, p = 0.017), with patients with CM + MOH making significantly more disadvantageous decisions than patients with CM (p = 0.024) and HCs (p = 0.008), while the CM and HC groups did not differ (p = 0.690). By contrast, there was no significant difference between the groups in the Cambridge Gambling Task and the Wisconsin Card Sorting Test. Furthermore, performance on the Iowa Gambling Task was inversely correlated with analgesic consumption (r = -0.41, p = 0.003), suggesting that decision-making under ambiguity may be related to MOH.

CONCLUSIONS

Our data suggest that patients with CM + MOH had impaired decisions under ambiguous, but not risky situations. This dissociation indicates disrupted emotional feedback processing rather than executive dysfunction, which may underlie the pathogenesis of MOH.

Imaging the brain and vascular reactions to headache treatments: a systematic review

BACKGROUND

Neuroimaging studies have made an important contribution to our understanding of headache pathophysiology. This systematic review aims to provide a comprehensive overview and critical appraisal of mechanisms of actions of headache treatments and potential biomarkers of treatment response disclosed by imaging studies.

MAIN BODY

We performed a systematic literature search on PubMed and Embase databases for imaging studies investigating central and vascular effects of pharmacological and non-pharmacological treatments used to abort and prevent headache attacks. Sixty-three studies were included in the final qualitative analysis. Of these, 54 investigated migraine patients, 4 cluster headache patients and 5 patients with medication overuse headache. Most studies used functional magnetic resonance imaging (MRI) (n = 33) or molecular imaging (n = 14). Eleven studies employed structural MRI and a few used arterial spin labeling (n = 3), magnetic resonance spectroscopy (n = 3) or magnetic resonance angiography (n = 2). Different imaging modalities were combined in eight studies. Despite of the variety of imaging approaches and results, some findings were consistent. This systematic review suggests that triptans may cross the blood-brain barrier to some extent, though perhaps not sufficiently to alter the intracranial cerebral blood flow. Acupuncture in migraine, neuromodulation in migraine and cluster headache patients, and medication withdrawal in patients with medication overuse headache could promote headache improvement by reverting headache-affected pain processing brain areas. Yet, there is currently no clear evidence for where each treatment acts, and no firm imaging predictors of efficacy. This is mainly due to a scarcity of studies and heterogeneous treatment schemes, study designs, subjects, and imaging techniques. In addition, most studies used small sample sizes and inadequate statistical approaches, which precludes generalizable conclusions.

CONCLUSION

Several aspects of headache treatments remain to be elucidated using imaging approaches, such as how pharmacological preventive therapies work, whether treatment-related brain changes may influence therapy effectiveness, and imaging biomarkers of clinical response. In the future, well-designed studies with homogeneous study populations, adequate sample sizes and statistical approaches are needed.

Chronic migraine and medication overuse

Though clearly described as far back as the 17th century, chronic migraine has defied precise categorization and has continued to develop as an important diagnostic concept with significant societal impact. Worldwide prevalence is estimated to be between 1% and 3%, and these patients form a dynamic group cycling between chronic and episodic migraine. Theories of pathogenesis are developing supported by recent imaging and other findings. Of the many determinants of progression to chronic migraine, overuse of acute abortive headache medications may be one of the most important modifiable factors. Treatment strategies, in addition to educational measures, have included various preventive migraine medications such as topiramate, valproate, and onabotulinumtoxinA. CGRP monoclonal antibodies are efficacious for the management of chronic migraine both with and without medication overuse.

High-Density Electroencephalography-Informed Multiband Functional Magnetic Resonance Imaging Reveals Rhythm-Specific Activations Within the Trigeminal Nociceptive Network

The interest in exploring trigeminal pain processing has grown in recent years, mainly due to various pathologies (such as migraine) related to this system. However, research efforts have mainly focused on understanding molecular mechanisms or studying pathological states. On the contrary, non-invasive imaging studies are limited by either spatial or temporal resolution depending on the modality used. This can be overcome by using multimodal imaging techniques such as simultaneous functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Although this technique has already been applied to neuroscientific research areas and consequently gained insights into diverse sensory systems and pathologies, only a few studies have applied EEG-fMRI in the field of pain processing and none in the trigeminal system. Focusing on trigeminal nociception, we used a trigeminal pain paradigm, which has been well-studied in either modality. For validation, we first acquired stand-alone measures with each imaging modality before fusing them in a simultaneous session. Furthermore, we introduced a new, yet simple, non-parametric correlation technique, which exploits trial-to-trial variance of both measurement techniques with Spearman’s correlations, to consolidate the results gained by the two modalities. This new technique does not presume a linear relationship and needs a few repetitions per subject. We also showed cross-validation by analyzing visual stimulations. Using these techniques, we showed that EEG power changes in the theta-band induced by trigeminal pain correlate with fMRI activation within the brainstem, whereas those of gamma-band oscillations correlate with BOLD signals in higher cortical areas.

Gray matter alteration in medication overuse headache: a coordinates-based activation likelihood estimation meta-analysis

Medication overuse headache (MOH) is a prevalent secondary headache, bringing heavy economic burden and neuropsychological damage. Neuroimaging studies on the disease reported divergent results. To merge the reported neuroimaging alterations in MOH patients and explore a pathophysiological mechanism of this disorder. A meta-analytic activation likelihood estimation (ALE) analysis method was used. We systematically searched English and Chinese databases for both morphological and functional neuroimaging studies published before Nov 18, 2021. Reported altered brain regions and the stereotactic coordinates of their peaks were extracted and pooled by GingerALE using Gaussian probability distribution into brain maps, illustrating converged regions of alteration among studies. We identified 927 articles, of which five studies on gray matter changes, using voxel-based morphometry (VBM) were eventually included for ALE analysis, with 344 subjects and 54 coordinates put into GingerALE. No functional magnetic resonance imaging (fMRI) or positron emission topography (PET) studies were included for pooling. Compared with healthy controls (HCs), MOH featured increased gray matter density in midbrain, striatum, cingulate, inferior parietal cortex and cerebellum (P < 0.001 uncorrected), whereas decreased gray matter density in orbitofrontal cortex (P < 0.05, family-wise error), frontal, insular and parietal cortices (P < 0.001 uncorrected). Withdrawal of analgesics led to decreased gray matter density in superior temporal gyrus, cuneus, midbrain and cerebellum (P < 0.001 uncorrected). This meta-analysis confirmed that medication overuse headache is associated with morphologic alteration in the reward system, the prefrontal cortex and a reversible modification in the pain network. Further functional imaging paradigms and longitudinal studies are required for a more definite conclusion and a causal mechanism.

Clinical and biobehavioral perspectives: Is medication overuse headache a behavior of dependence?

Medication overuse headache (MOH), previously known as analgesic abuse headache or medication misuse headaches, is a common form of chronic headache disorder that has a detrimental impact on health and society. Although it has been widely accepted that overusing abortive medications is paradoxically the cause of MOH and drug discontinuation is the treatment of choice, ongoing debates exist as to whether drug consumption per se is the cause or consequence of headache chronification. Certain features in MOH such as their compulsive drug-seeking behavior, withdrawal headaches and high relapse rates share similarities with drug dependence, suggesting that there might be common underlying biological and psychobehavioral mechanisms. In this regard, this article will discuss the updated evidence and current debates on the possible biobehavioral overlap between MOH and drug dependence. To begin with, we will discuss whether MOH has characteristics of substance dependence based on standard psychiatry diagnostic criteria and other widely used dependence scales. Recent epidemiological studies underscoring common psychiatric comorbidities between the two disorders will also be presented. Although both demonstrate seemingly distinct personality traits, recent studies revealed similar decision-making impairment from a cognitive perspective, indicating the presence of a maladaptive reward system in both disorders. In addition, emerging imaging studies also support this notion by showing reversible morphological and functional brain changes related to the mesocorticolimbic reward circuitry in MOH, with a strong resemblance to those in addiction. Finally, an increased familial risk for drug dependence and genetic association with dopaminergic and drug dependence molecular pathways in MOH also support a possible link between MOH and addiction. Understanding the role of dependence in MOH will have a great impact on disease management as this will provide the missing piece of the puzzle in current therapeutic strategies.

Medication overuse headache: an overview of clinical aspects, mechanisms, and treatments

INTRODUCTION

Medication-overuse headache (MOH) is a common debilitating neurological disorder, with a prevalence of 1% to 7% in general population. It affects more than 60 million people worldwide and provokes substantial burden. Despite that, most practitioners don't know MOH. This review aims at presenting MOH clinical features, pathophysiology insights, and recent knowledge and guidance regarding treatments.

AREAS COVERED

A literature search in the major medical databases including the terms 'medication overuse headache,' 'chronic daily headache,' 'chronic migraine,' 'symptomatic medication overuse' and others, published between 1990 and 2020, was carried out.

EXPERT COMMENTARY

Primary headache sufferers such as migraineurs and tension-type headache patients may increase the headache frequency and induce the transition from episodic to chronic forms, as well as develop MOH, in the presence of medication overuse. There is evidence of structural and functional changes in some areas of the brain, which may identify those likely to respond or not to treatments. Despite the geographical differences and lack of consensus regarding approaches, to educate the patients about reducing medication intake, to withdraw overused medications and to start prophylaxis in some sufferers are crucial steps. Emerging treatments as monoclonal antibodies to migraine may result in better adherence and tolerability profiles as well as outcomes.

Brain Structural and Functional Imaging Findings in Medication-Overuse Headache

This chapter overviews research neuroimaging findings of patients with medication-overuse headache (MOH). Results indicate; (i) correlations between neuropathology and medication-overuse; (ii) changes in brain morphology and cortical function; and (iii) brain recovery subsequent to withdrawal of medication that was overused. Results of this narrative review indicate exacerbated brain structural and functional changes in regions of the pain-matrix and in regions of the mesocortical-limbic circuit in patients with MOH compared to patients with migraine or compared to healthy controls. Modification of brain morphology as well as an association between brain recovery and medication withdrawal suggest that the MOH disease process involves state (brain modification) and trait-like (brain adaptation and recovery) neuromechanisms.

Pathophysiology, prevention, and treatment of medication overuse headache

Regular or frequent use of analgesics and acute antimigraine drugs can increase the frequency of headache, and induce the transition from episodic to chronic headache or medication overuse headache. The 1-year prevalence of this condition in the general population is between 1% and 2%. Medication overuse headache is more common in women and in people with comorbid depression, anxiety, and other chronic pain conditions. Treatment of medication overuse headache has three components. First, patients need education and counselling to reduce the intake of medication for acute headache attacks. Second, some patients benefit from drug withdrawal (discontinuation of the overused medication). Finally, preventive drug therapy and non-medical prevention might be necessary in patients at onset of treatment or in patients who do not respond to the first two steps. The optimal therapeutic approach requires validation in controlled trials.

Withdrawal from acute medication normalises short-term cortical synaptic potentiation in medication overuse headache

OBJECTIVES

To study the effects of a standard acute medication withdrawal program on short-term cortical plasticity mechanisms in patients with medication overuse headache (MOH).

METHODS

Thirteen patients with MOH and 16 healthy volunteers underwent repetitive transcranial magnetic stimulation (rTMS) over the left motor cortex; in patients with MOH, recordings were performed before and after a 3-week medication withdrawal program. Ten trains of 10 stimuli each (120% resting motor threshold) were delivered at 1 Hz or 5 Hz in two separate sessions in a randomised order. Motor evoked potential (MEP) amplitudes were measured from the right first dorsal interosseous muscle and the slope of the linear regression line from the first to the tenth stimuli was calculated for each participant.

RESULTS

All subjects exhibited MEP amplitude inhibition in response to 1 Hz rTMS. Alternatively, the 5-Hz trains of rTMS inhibited rather than potentiated MEP amplitudes in patients with MOH. The physiological potentiating effect of 5 Hz rTMS on MEP amplitudes was restored after drug withdrawal and in proportion with the percentage reduction in monthly headache days in patients with MOH.

CONCLUSIONS

The results suggest that acute medication withdrawal normalises brain responses in patients with MOH. Clinical improvements after medication withdrawal may reflect the reversal of neurophysiological dysfunction. Accordingly, medication withdrawal should be offered to patients with MOH as early as possible in order to prevent the development of more pronounced alterations in brain plasticity.