Rebalancing NOX2/Nrf2 to limit inflammation and oxidative stress across gut-brain axis in migraine

Migraine is one of the most common neurological illnesses, and it is characterized by complicated neurobiology. It was confirmed the influence of inflammation and oxidative stress in migraines and also in distal organs such as the intestine. Indeed, the constant bidirectional communication between the Central Nervous System (CNS) and the gastrointestinal (GI) tract, known as the gut-brain axis, has become an attractive target involved in different human disorders. Herein, we explored the role of NADPH oxidase 2 (NOX2) in nitroglycerin (NTG)-induced migraine in mice models to discover the mechanism by which, during migraine attack, oxidative stress is sustained within trigeminal neurons and GI. Considering the inverse relationship between NOX2 and Nrf2, Nrf2 upregulation seems to be a promising approach to decrease NOX2 expression and consequently limit oxidative stress and inflammation spread in neurological and non-neurological diseases. With this aim, we exploited tempol's Nrf2-inducer ability to better understand the involvement of Nrf2/NOX2 axis in migraine and associated GI comorbidities. Behavioral tests confirmed that tempol, in a dose-dependent manner, moderated clinical signs of migraine and abdominal pain. Moreover, we demonstrated that the decrease in migraine-related symptomatology was strongly linked to the modulation of Nrf2/NOX2 signaling pathway in the brain and colon. In the brain, the rebalancing of Nrf2/NOX2 prevented neuronal loss, decreased glia reactivity while inhibiting NF-κB and NLRP3 inflammasome activation. In the colon, Nrf2 upregulation and consequent NOX2 decrease reduced the histological damage, mast cells infiltration as well as tumor necrosis factor (TNF)-α and interleukin (IL)-1β release. Furthermore, the attenuation of inflammation and oxidative stress led to the restoration of the intestinal barrier through TJs replacement. Taken as a whole, data suggested that the regulation of Nrf2/NOX2 balance is a successful way to reduce neurological and related intestinal impairments during migraine and could be of relevance for migraine-like attacks in humans.

Inhibition of Nociception in a Preclinical Episodic Migraine Model by Dietary Supplementation of Grape Seed Extract Involves Activation of Endocannabinoid Receptors

Migraine is associated with peripheral and central sensitization of the trigeminal system and dysfunction of descending pain modulation pathways. Recently, dietary inclusion of grape seed extract (GSE) was shown to inhibit mechanical nociception in a preclinical model of chronic temporomandibular joint disorder, a condition often comorbid with migraine, with the antinociceptive effect mediated, in part, by activation of 5-HT3/7 and GABAB receptors. This study further investigated the mechanisms by which GSE inhibits mechanical nociception in a preclinical model of episodic migraine. Hyperalgesic priming of female and male Sprague Dawley rats was induced by three consecutive daily two-hour episodes of restraint stress. Seven days after the final restraint stress, rats were exposed to pungent odors from an oil extract that contains the compound umbellulone, which stimulates CGRP release and induces migraine-like pain. Some animals received dietary supplementation of GSE in their drinking water beginning one week prior to restraint stress. Changes in mechanical sensitivity in the orofacial region and hindpaw were determined using von Frey filaments. To investigate the role of the endocannabinoid receptors in the effect of GSE, some animals were injected intracisternally with the CB1 antagonist AM 251 or the CB2 antagonist AM 630 prior to odor inhalation. Changes in CGRP expression in the spinal trigeminal nucleus (STN) in response to stress, odor and GSE supplementation were studied using immunohistochemistry. Exposure of stress-primed animals to the odor caused a significant increase in the average number of withdrawal responses to mechanical stimulation in both the orofacial region and hindpaw, and the effect was significantly suppressed by daily supplementation with GSE. The anti-nociceptive effect of GSE was inhibited by intracisternal administration of antagonists of CB1 and CB2 receptors. GSE supplementation inhibited odor-mediated stimulation of CGRP expression in the STN in sensitized animals. These results demonstrate that GSE supplementation inhibits trigeminal pain signaling in an injury-free model of migraine-like pain via activation of endocannabinoid receptors and repression of CGRP expression centrally. Hence, we propose that GSE may be beneficial as a complementary migraine therapeutic.

Gut microbiota and migraine

Migraine is a leading cause of disability among the adult population and is a significant burden on the economies of the world. Studies into the underlying causes of migraine have spanned centuries but its underlying mechanisms are still not fully understood. In recent years, accumulating evidence implicates that microbiota-mediated gut-brain crosstalk may contribute to the pathogenesis of migraine. This review provides a brief account of the history of migraine theories and summarizes the recent studies showing how gut microbiota is involved in the pathophysiology of migraine. Future research perspectives for better understanding the role of the gut microbiota in migraine are also discussed.

Migraine and Its Equivalents: What Do They Share? A Narrative Review on Common Pathophysiological Patterns

Migraine is the first in order of frequency of the neurological disorders, affecting both adult and paediatric populations. It is also the first cause of primary headaches in children. Migraine equivalents are periodic disorders that can be associated with migraine or considered as prognostic features of a future migraine manifestation. Despite the mechanisms underlying migraine and its equivalents are not entirely clear, several elements support the hypothesis of common pathophysiological patterns shared by these conditions. The aim of this review is thus to analyze the literature in order to highlight which currently known mechanisms may be common between migraine and its equivalents.

Voluntary Wheel Running Partially Attenuates Early Life Stress-Induced Neuroimmune Measures in the Dura and Evoked Migraine-Like Behaviors in Female Mice

Migraine is a complex neurological disorder that affects three times more women than men and can be triggered by endogenous and exogenous factors. Stress is a common migraine trigger and exposure to early life stress increases the likelihood of developing chronic pain disorders later in life. Here, we used our neonatal maternal separation (NMS) model of early life stress to investigate whether female NMS mice have an increased susceptibility to evoked migraine-like behaviors and the potential therapeutic effect of voluntary wheel running. NMS was performed for 3 h/day during the first 3 weeks of life and initial observations were made at 12 weeks of age after voluntary wheel running (Exercise, -Ex) or sedentary behavior (-Sed) for 4 weeks. Mast cell degranulation rates were significantly higher in dura mater from NMS-Sed mice, compared to either naïve-Sed or NMS-Ex mice. Protease activated receptor 2 (PAR2) protein levels in the dura were significantly increased in NMS mice and a significant interaction of NMS and exercise was observed for transient receptor potential ankyrin 1 (TRPA1) protein levels in the dura. Behavioral assessments were performed on adult (>8 weeks of age) naïve and NMS mice that received free access to a running wheel beginning at 4 weeks of age. Facial grimace, paw mechanical withdrawal threshold, and light aversion were measured following direct application of inflammatory soup (IS) onto the dura or intraperitoneal (IP) nitroglycerin (NTG) injection. Dural IS resulted in a significant decrease in forepaw withdrawal threshold in all groups of mice, while exercise significantly increased grimace score across all groups. NTG significantly increased grimace score, particularly in exercised mice. A significant effect of NMS and a significant interaction effect of exercise and NMS were observed on hindpaw sensitivity following NTG injection. Significant light aversion was observed in NMS mice, regardless of exercise, following NTG. Finally, exercise significantly reduced calcitonin gene-related peptide (CGRP) protein level in the dura of NMS and naïve mice. Taken together, these findings suggest that while voluntary wheel running improved some measures in NMS mice that have been associated with increased migraine susceptibility, behavioral outcomes were not impacted or even worsened by exercise.

Episodic migraine and chest pain as the first manifestation of small cell lung carcinoma

Migraine-like associated with chest pain is an alarming association and forces us to rule out the presence of a secondary cause. That must be taken into account in the differential diagnosis of craniofacial hemicranial pain that appears in patients with no personal history of headache, and risk factors for the development of pulmonary neoplasia.

Migraine and Complex Regional Pain Syndrome: A Case-Referent Clinical Study

We studied clinical phenotype differences between migraineurs with CRPS (Mig + CRPS) and those without (Mig − CRPS). Mig + CRPS cases and Mig − CRPS referents aged ≥18 years were enrolled. Diagnosis was made in accordance with International Classification of Headache Disorders-3 beta (ICHD-3 beta) for migraine and Budapest Criteria for CRPS. Migraines both with and without aura were included. A total of 70 Mig + CRPS cases (13% males, mean age 48 years) and 80 Mig − CRPS referents (17% males, mean age 51 years) were included. 33% of Mig + CRPS and 38% of Mig − CRPS exhibited episodic migraine (EM) while 66% of Mig + CRPS and 62% of Mig − CRPS had chronic migraine (CM) (OR = 0.98, CI 0.36, 2.67). Median duration of CRPS was 3 years among EM + CRPS and 6 years among CM + CRPS cohort (p < 0.02). Mig + CRPS (57%) carried higher psychological and medical comorbidities compared to Mig − CRPS (6%) (OR 16.7, CI 10.2, 23.6). Higher migraine frequency was associated with longer CRPS duration. Migraineurs who developed CRPS had higher prevalence of psychological and medical disorders. Alleviating migraineurs' psychological and medical comorbidities may help lower CRPS occurrence.

Case Studies of Uncommon and Rare Headache Disorders

The following 6 case studies are presented: a 12-day migraine with recurring aura?; a migraineur with a new constant headache for 1 month; an orthostatic headache; a unilateral headache; migraine with aura and limb pain without headache; and nocturnal headaches. These cases illustrate the fascinating diversity and challenges of primary and secondary headaches that neurologists commonly encounter.

Familial limb pain and migraine: 8-year follow-up of four generations

Background Migraine limb pain may be under-recognized in adults and children. There is little information about familial forms of this disorder. Objectives To describe the clinical and inheritance patterns of familial migraine limb pain over four generations and to review the evidence for limb pain as a manifestation of migraine. Methods Prospective clinical and pedigree analysis with an 8-year follow-up of 27 family members. Results Eight members of the family had benign recurrent limb pain associated with headache in a dominant inheritance pattern. Limb pain occurred before, during or after the headache, with probable or definite migraine with aura, migraine without aura and lower-half headache. The limb pain fulfilled the International Headache Society criteria for aura in six patients and also occurred without headache in three. Four members of the family had recurrent abdominal pain and/or motion sickness in childhood. Conclusions This is the first report of dominant familial limb pain temporally associated with migraine headache, starting in adulthood or starting in childhood and continuing into adulthood. A search for a genetic marker is indicated. Limb pain should be included as a childhood periodic syndrome linked to migraine and recognized as part of the migraine spectrum in adults.

Clinical and electroencephalographic abnormalities during the full duration of a sporadic hemiplegic migraine attack

Electroencephalographic (EEG) abnormalities have been reported during migraine attacks but their spatial and temporal distributions are not well known. We report the temporospatial dynamics of EEG during the full duration of a migraine attack with aura in a 19-year-old woman. She experienced episodes of hemiplegic migraine since the age of 2.5 years, with right hemibody paralysis preceded by visual symptoms. She reported severe pain of the right hemibody just before hemiplegia that was enventually suggestive of possible epileptic seizure, justifying diagnostic video-EEG monitoring. Sporadic hemiplegic migraine was diagnosed in the absence of family history. EEG was normal at the beginning of visual aura. After 15minutes, posterior slow waves appeared over the migrainous hemisphere, spreading progressively towards anterior regions: first the central region (5minutes after onset of contralateral hemiplegia), then the frontal region and over both hemispheres. A new de novo mutation was identified in the SCN1A gene.

The Frequent Unusual Headache Syndromes: A Proposed Classification Based on Lifetime Prevalence

BACKGROUND

There is no agreement on a single cutoff point or prevalence for regarding a given disease as rare. The concept of what is a rare headache disorder is even less clear and the spectrum from a very frequent, frequent, occasional to rare headache syndrome is yet to be established.

OBJECTIVE

An attempt has been made to estimate the lifetime prevalence of each of the headache subtypes classified in the ICHD-II.

METHOD

Using the ICHD-II, 199 different headache subtypes were identified. The following classification was made according to the estimated lifetime prevalence of each headache disorder: very frequent (prevalence >10%); frequent (between 1 and 10%); occasional (between 0.07 and 1%); and unusual or rare (<0.07%).

RESULTS

One hundred and fifty-four of 199 (77%) were categorized as unusual headache disorders, 7/199 (4%) as very frequent, 9/199 (5%) as frequent, and 29/199 (15%) as occasional forms of headache disorder.

CONCLUSION

The unusual headache syndromes do not appear to be as infrequent in clinical practice as has been generally believed. About three-fourths of the classified headache disorders found in the ICHD-II can be considered as rare. This narrative review article may be regarded as an introduction to the concept of unusual headaches and a proposed classification of all headaches (at least those listed in the ICHD-II).

Abdominal and lower back pain in pediatric idiopathic stabbing headache

Idiopathic stabbing headache (ISH) is a primary headache syndrome characterized by transient, sharp, stabbing pains located in the first division of the trigeminal nerve. Reports of pediatric ISH are rare, and extracephalic pain in pediatric ISH is extremely rare. Here we report the case of a 7-year-old male patient suffering from frequent, short, stabbing headache, which was occasionally associated with abdominal and lower back pain. Various investigations were normal. He was diagnosed with ISH, and valproic acid was administered to relieve his headache and accompanying symptoms. Our case demonstrates that abdominal and lower back pain may occur in pediatric ISH. This case may provide new evidence linking ISH and migraine by showing that extracephalic symptoms accompanying ISH are similar to those of migraine. We hypothesize that the mechanism underlying the headache and abdominal and lower back pain associated with ISH may be similar to that of a migraine headache. Accumulating additional cases by asking specific questions regarding the presence of the unusual symptoms presented in our case may help to establish a detailed clinical profile of these unfamiliar and peculiar symptoms in the pediatric ISH population.

Recent progress in migraine pathophysiology: role of cortical spreading depression and magnetic resonance imaging

Migraine is characterised by debilitating pain, which affects the quality of life in affected patients in both the western and the eastern worlds. The purpose of this article is to give a detailed outline of the pathophysiology of migraine pain, which is one of the most confounding pathologies among pain disorders in clinical conditions. We critically evaluate the scientific basis of various theories concerning migraine pathophysiology, and draw insights from brain imaging approaches that have unraveled the prevalence of cortical spreading depression (CSD) in migraine. The findings supporting the role of CSD as a physiological substrate in clinical pain are discussed. We also give an exhaustive overview of brain imaging approaches that have been employed to solve the genesis of migraine pain, and its possible links to the brainstem, the neocortex, genetic endophenotypes, and pathogenetic factors (such as dopaminergic hypersensitivity). Furthermore, a roadmap is proposed to provide a better understanding of pain pathophysiology in migraine, to enable the development of strategies using leads from brain imaging studies for the identification of early biomarkers, efficient prognosis, and treatment planning, which eventually may help in alleviating some of the devastating impact of pain morbidity in patients afflicted with migraine.

Migraine: mimics, borderlands and chameleons

Diagnostically, headache is the easy part of migraine. It is the surrounds of migraine--the aura, prodrome and postdrome--that can be most challenging, and confused with other pathologies. This article examines the definition and variants of migraine; alternative diagnoses for which migraine may be mistaken (mimics); conditions that lie between migraine and other diagnoses (borderlands) and the possible presentations of migraine posing as other conditions (chameleons). The focus is on adults, with only passing reference to children. Migraine is more often a chameleon than a mimic; and it is the careful history that usually makes the distinction. Given migraine's prevalence of 10-15%, relatively uncommon features of migraine occur quite often, in comparison with frequent manifestations of less common diseases. Thus, even rare or under-recognised presentations of migraine come into the differential diagnosis of many presentations.

Lower back pain as a symptom of migrainous corpalgia

The symptoms and prevalence of migraine headaches are widely recognized; however, less is known about migraine-related spontaneous body pain, or migrainous corpalgia. Only a few reports have described it. The case of a 13-year-old boy with onset of migrainous corpalgia at the age of 12 years is presented. He suffered from pulsatile headaches and bilateral lower back pain, which would appear either with the headache or as an isolated symptom. Various medical examinations showed no abnormalities. He was diagnosed as having migraine without aura and successfully treated with valproic acid. It is unique for this patient to have lower back pain as a symptom of migrainous corpalgia. It would be important for physicians to understand the variety of pain symptoms in migraine patients, as shown here, for better and comprehensive understanding of migraine and its related condition.

Unilateral nasal pain with migraine features

BACKGROUND

Migraine attacks exclusively felt in the face are very rare, the pain involving the territories supplied by the second and third branches of the trigeminal nerve.

CASES

Two patients suffering from heminasal pain attacks accompanied with typical migrainous features and responsive to oral or intranasal triptans - but not to intranasal lidocaine or oxymetazoline. In one patient, the attacks could be precipitated upon slight touching on the tip of the nose, in the other attacks were preceded by the nasal sensation typically heralding sneezing.

DISCUSSION

Migraine pain mostly develops within the innervation territory of the first branch of the trigeminal nerve, which includes the nose. Therefore, episodes of unilateral nasal pain with migrainous features could be considered a migraine with unusual topography (nasal migraine). Painful nasal attacks occasionally preceded by stimulation of trigeminal afferents in the nose, could be conceived of as migraine-tic syndrome.

12 item Allodynia Symptom Checklist/Brasil: cross-cultural adaptation, internal consistency and reproducibility

Since there was no Portuguese questionnaire to evaluate cutaneous allodynia, which has been pointed out as a risk factor of migraine, we aimed to perform the cross-cultural adaptation of the 12 item Allodynia Symptom Checklist for the Brazilian population and to test its measurement properties. It consisted in six stages: translation, synthesis, back translation, revision by a specialist committee, pretest and submission the documents to the committee. In the pretest stage, the questionnaire was applied to 30 migraineurs of both sexes, who had some difficulty in understanding it. Thus, a second version was applied to 30 additional subjects, with no difficulties being reported. The mean filling out time was 3'36", and the internal consistency was 0.76. To test reproducibility, 15 other subjects filled out the questionnaire at two different times, it was classified as moderate (weighted kappa=0.58). We made available to Brazilian population an easy, quick and reliable questionnaire.

Indwelling supradural catheters for induction of facial allodynia: surgical procedures, application of inflammatory stimuli, and behavioral testing

Migraine headaches are debilitatingly painful and poorly managed. Facial allodynia is often associated with migraine, and clinical evidence indicates that it is a critical point in migraine progression. That is, if the migraine can be treated prior to the onset of facial allodynia, the migraine can be halted using triptans, whereas if treatment is administered after facial allodynia has begun, the treatment is ineffective. The meninges and the immune cells therein have been implicated in migraine facial pain. Indeed, application of inflammatory mediators over the meninges has been used to study changes in pain responsive neurons in trigeminal complex, and changes in their receptive fields. Much of this research has been carried out in anesthetized rats, which limits the clinical application. Our indwelling supradural catheter model, in which inflammatory mediators can be administered to the meninges in awake and freely moving rats, allows for the assessment of behavioral changes shortly after injection. Following administration of inflammatory soup (histamine, serotonin, bradykinin, and prostaglandin E2) or the immunogenic HIV-1 coat protein gp120 results in reliable periorbital mechanical allodynia. This model provides an additional means to study the neurocircuitry and neuropharmacology of facial allodynia. Here, we describe detailed methods for the placement of the catheter, injection procedures, and assessment of facial allodynia.

Migraine may be a risk factor for the development of complex regional pain syndrome

The aim was to assess the relative frequency of migraine and the headache characteristics of complex regional pain syndrome (CRPS) sufferers. CRPS and migraine are chronic, often disabling pain syndromes. Recent studies suggest that headache is associated with the development of CRPS. Consecutive adults fulfilling International Association for the Study of Pain criteria for CRPS at a pain clinic were included. Demographics, medical history, and pain characteristics were obtained. Headache diagnoses were made using International Classification of Headache Disorders, 2nd edn criteria. Migraine and pain characteristics were compared in those with migraine with those without. anova with Tukey post hoc tests was used to determine the significance of continuous variables and Fisher's exact or χ(2) tests for categorical variables. The expected prevalence of migraine and chronic daily headache (CDH) was calculated based on age- and gender-stratified general population estimates. Standardized morbidity ratios (SMR) were calculated by dividing the observed prevalence of migraine by the expected prevalence from the general population. The sample consisted of 124 CRPS participants. The mean age was 45.5 ± 12.0 years. Age- and gender-adjusted SMRs showed that those with CRPS were 3.6 times more likely to have migraine and nearly twice as likely to have CDH as the general population. Aura was reported in 59.7% (74/124) of participants. Of those CRPS sufferers with migraine, 61.2% (41/67) reported the onset of severe headaches before the onset of CRPS symptoms Mean age of onset of CRPS was earlier in those with migraine (34.9 ± 11.1 years) and CDH (32.5 ± 13.4 years) compared with those with no headaches (46.8 ± 14.9 years) and those with tension-type headache (TTH) (39.9 ± 9.9 years), P < 0.05. More extremities were affected by CRPS in participants with migraine (median of four extremities) compared with the combined group of those CRPS sufferers with no headaches or TTH (median 2.0 extremities), P < 0.05. The presence of static, dynamic and deep joint mechano-allodynia together was reported by more CRPS participants with migraine (72.2%) than those with no headaches or TTH (46.2%), P ≤ 0.05. Migraine may be a risk factor for CRPS and the presence of migraine may be associated with a more severe form of CRPS. Specifically: (i) migraine occurs in a greater percentage of CRPS sufferers than expected in the general population; (ii) the onset of CRPS is reported earlier in those with migraine than in those without; and (iii) CRPS symptoms are present in more extremities in those CRPS sufferers with migraine compared with those without. In addition, as we also found that the presence of aura is reported in a higher percentage of those CRPS sufferers with migraine than reported in migraineurs in the general population, further evaluation of the cardiovascular risk profile of CRPS sufferers is warranted.

Central sensitization: implications for the diagnosis and treatment of pain

Nociceptor inputs can trigger a prolonged but reversible increase in the excitability and synaptic efficacy of neurons in central nociceptive pathways, the phenomenon of central sensitization. Central sensitization manifests as pain hypersensitivity, particularly dynamic tactile allodynia, secondary punctate or pressure hyperalgesia, aftersensations, and enhanced temporal summation. It can be readily and rapidly elicited in human volunteers by diverse experimental noxious conditioning stimuli to skin, muscles or viscera, and in addition to producing pain hypersensitivity, results in secondary changes in brain activity that can be detected by electrophysiological or imaging techniques. Studies in clinical cohorts reveal changes in pain sensitivity that have been interpreted as revealing an important contribution of central sensitization to the pain phenotype in patients with fibromyalgia, osteoarthritis, musculoskeletal disorders with generalized pain hypersensitivity, headache, temporomandibular joint disorders, dental pain, neuropathic pain, visceral pain hypersensitivity disorders and post-surgical pain. The comorbidity of those pain hypersensitivity syndromes that present in the absence of inflammation or a neural lesion, their similar pattern of clinical presentation and response to centrally acting analgesics, may reflect a commonality of central sensitization to their pathophysiology. An important question that still needs to be determined is whether there are individuals with a higher inherited propensity for developing central sensitization than others, and if so, whether this conveys an increased risk in both developing conditions with pain hypersensitivity, and their chronification. Diagnostic criteria to establish the presence of central sensitization in patients will greatly assist the phenotyping of patients for choosing treatments that produce analgesia by normalizing hyperexcitable central neural activity. We have certainly come a long way since the first discovery of activity-dependent synaptic plasticity in the spinal cord and the revelation that it occurs and produces pain hypersensitivity in patients. Nevertheless, discovering the genetic and environmental contributors to and objective biomarkers of central sensitization will be highly beneficial, as will additional treatment options to prevent or reduce this prevalent and promiscuous form of pain plasticity.

A novel method for modeling facial allodynia associated with migraine in awake and freely moving rats

Migraine is a neurovascular disorder that induces debilitating headaches associated with multiple symptoms including facial allodynia, characterized by heightened responsivity to normally innocuous mechanical stimuli. It is now well accepted that immune activation and immune-derived inflammatory mediators enhance pain responsivity, including the trigeminal system. Nociceptive ("pain" responsive) trigeminal nerves densely innervate the cranial meninges. We have recently proposed that the meninges may serve as a previously unidentified, key interface between the peripheral immune system and the CNS with potential implications for understanding underlying migraine mechanisms. Our focus here is the development of a model for facial allodynia associated with migraine. We developed a model wherein an indwelling catheter is placed between the skull and dura, allowing immunogenic stimuli to be administered over the dura in awake and freely moving rats. Since the catheter does not contact the brain itself, any proinflammatory cytokines induced following manipulation derive from resident or recruited meningeal immune cells. While surgery alone does not alter immune activation markers, TNF or IL6 mRNA and/or protein, it does decrease gene expression and increase protein expression of IL-1 at 4 days after surgery. Using this model we show the induction of facial allodynia in response to supradural administration of either the HIV glycoprotein gp120 or inflammatory soup (bradykinin, histamine, serotonin, and prostaglandin E2), and the induction of hindpaw allodynia in our model after inflammatory soup. This model allows time- and dose-dependent assessment of the relationship between changes in meningeal inflammation and corresponding exaggerated pain behaviors.

Generalized Neck-Shoulder Hyperalgesia in Chronic Tension-Type Headache and Unilateral Migraine Assessed by Pressure Pain Sensitivity Topographical Maps of the Trapezius Muscle

Spatial changes in pressure pain hypersensitivity are present throughout the cephalic region (temporalis muscle) in both chronic tension-type headache (CTTH) and unilateral migraine. The aim of this study was to assess pressure pain sensitivity topographical maps on the trapezius muscle in 20 patients with CTTH and 20 with unilateral migraine in comparison with 20 healthy controls in a blind design. For this purpose, a pressure algometer was used to assess pressure pain thresholds (PPT) over 11 points of the trapezius muscle: four points in the upper part of the muscle, two over the levator scapulae muscle, two in the middle part, and the remaining three points in the lower part of the muscle. Pressure pain sensitivity maps of both sides (dominant/non-dominant; symptomatic/non-symptomatic) were depicted for patients and controls. CTTH patients showed generalized lower PPT levels compared with both migraine patients ( P = 0.03) and controls ( P < 0.001). The migraine group had also lower PPT than healthy controls ( P < 0.001). The most sensitive location for the assessment of PPT was the neck portion of the upper trapezius muscle in both patient groups and healthy controls ( P < 0.001). PPT was negatively related to some clinical pain features in both CTTH and unilateral migraine patients (all P < 0.05). Side-to-side differences were found in strictly unilateral migraine, but not in those subjects with bilateral pain, i.e. CTTH. These data support the influence of muscle hyperalgesia in both CTTH and unilateral migraine patients and point towards a general pressure pain hyperalgesia of neck-shoulder muscles in headache patients, particularly in CTTH.

Pressure Pain Sensitivity Mapping of the Temporalis Muscle Revealed Bilateral Pressure Hyperalgesia in Patients with Strictly Unilateral Migraine

Previous studies on pressure pain sensitivity in patients with migraine have shown conflicting results. There is emerging evidence suggesting that pain sensitivity is not uniformly distributed over the muscles, indicating the existence of topographical changes in pressure pain sensitivity. The aim of this study was to calculate topographical pressure pain sensitivity maps of the temporalis muscle in a blind design in patients with strictly unilateral migraine compared with controls. For this purpose, an electronic pressure algometer was used to measure pressure pain thresholds (PPT) over nine points of the temporalis muscle: three points in the anterior, medial and posterior parts, respectively. Pressure pain sensitivity maps of both sides (dominant or non-dominant; symptomatic or non-symptomatic) were calculated. The analysis of variance showed significant differences in PPT values between both groups ( F = 279.2; P < 0.001) and points ( F = 4.033; P < 0.001). Patients showed lower PPT at all nine points than healthy controls ( P < 0.001). We also found lower PPT in the centre of the muscle compared with the posterior part of the muscle within both groups ( P < 0.01). Interaction between group and points ( F = 1.9; P < 0.05) was also found. Within the migraine group, PPT levels were decreased bilaterally from the posterior to the anterior column of the temporalis muscle (Student-Newman-Keuls analysis; P < 0.05), with the most sensitive in the anterior part of the muscle. For controls, PPT did not follow such anatomical distribution, the most sensitive point being the centre of the mid-muscle belly. This study showed bilateral sensitization to pressure in unilateral migraine, suggesting the involvement of central components.

Recurrent limb pain and migraine: case reports and a clinical review

Recurrent limb pain (RLP) is a well-known entity in childhood. It is considered a precursor of migraine. The temporal relationship of RLP with headache in childhood is lacking in the literature. However, there are many cases with limb pain in a close temporal relationship with migraine headache in adults. We report six female patients with RLP and migraine and delineate the temporal relationship between the two. Three patients had a history of RLP in childhood and developed migraine headache after many years. Conversely, two patients had a long history of migraine headache and later developed RLP. One patient developed RLP and migraine headache at the same age. Isolated limb pain was frequent in all six patients. It was mild to severe, for a few minutes to a few days, and predominantly located in the upper extremities. Only one patient reported allodynia. The patients showed response to preventive measures (all six patients) and abortive therapies (four patients), even in those attacks of RLP that were not associated with headache episodes. We also review the clinical profiles of the patients in whom RLP and migraine were related to each other, and speculate on the possible mechanisms for RLP in the patients with migraine.