Depression of home cage wheel running: a reliable and clinically relevant method to assess migraine pain in rats

BACKGROUND

The development of new anti-migraine treatments is limited by the difficulty inassessing migraine pain in laboratory animals. Depression of activity is one of the few diagnostic criteria formigraine that can be mimicked in rats. The goal of the present study was to test the hypothesis thatdepression of home cage wheel running is a reliable and clinically relevant method to assess migraine painin rats.

METHODS

Adult female rats were implanted with a cannula to inject allyl isothiocyanate (AITC) onto the dura to induce migraine pain, as has been shown before. Rats recovered from implantation surgery for 8 days in cages containing a running wheel. Home cage wheel running was recorded 23 h a day. AITC and the migraine medication sumatriptan were administered in the hour prior to onset of the dark phase.

RESULTS

Administration of AITC caused a concentration-dependent decrease in wheel running that lasted 3 h. The duration and magnitude of AITC-induced depression of wheel running was consistent following three repeated injections spaced 48 h apart. Administration of sumatriptan attenuated AITC-induced depressionof wheel running when a large dose (1 mg/kg) was administered immediately following AITC administration. Wheel running patterns did not change when sumatriptan was given to naïve rats.

CONCLUSIONS

These data indicate that home cage wheel running is a sensitive, reliable, and clinically relevant method to assess migraine pain in the rat.

Electroacupuncture at Fengchi (GB20) inhibits calcitonin gene-related peptide expression in the trigeminovascular system of a rat model of migraine

Most migraine patients suffer from cutaneous allodynia; however, the underlying mechanisms are unclear. Calcitonin gene-related peptide (CGRP) plays an important role in the pathophysiology of migraine, and it is therefore, a potential therapeutic target for treating the pain. In the present study, a rat model of conscious migraine, induced by repeated electrical stimulation of the superior sagittal sinus, was established and treated with electroacupuncture at Fengchi (GB20) (depth of 2–3 mm, frequency of 2/15 Hz, intensity of 0.5–1.0 mA, 15 minutes/day, for 7 consecutive days). Electroacupuncture at GB20 significantly alleviated the decrease in hind paw and facial withdrawal thresholds and significantly lessened the increase in the levels of CGRP in the trigeminal ganglion, trigeminal nucleus caudalis and ventroposterior medial thalamic nucleus in rats with migraine. No CGRP-positive cells were detected in the trigeminal nucleus caudalis or ventroposterior medial thalamic nucleus by immunofluorescence. Our findings suggest that electroacupuncture treatment ameliorates migraine pain and associated cutaneous allodynia by modulating the trigeminovascular system ascending pathway, at least in part by inhibiting CGRP expression in the trigeminal ganglion.

Trigeminal nervous system sensitization by infraorbital nerve injury enhances responses in a migraine model

Background

Although the peripheral and central sensitizations of trigeminal nervous system may be one of the important factors of migraine, the precise mechanism is not fully understood. In this study, we examined the influence of the sensitization of the second division of the trigeminal nerve (V2) by chronic constriction injury (CCI) of the infraorbital nerve (ION) on migraine headache, using the capsaicin-induced migraine model.

Methods

Male Sprague-Dawley rats were assigned to four groups: (a) sham surgery and topical-dural vehicle application (Sham + Vehicle) group, (b) CCI-ION and topical-dural vehicle application (CCI-ION + Vehicle) group, (c) sham surgery and topical-dural capsaicin application (Sham + Capsaicin) group, (d) CCI-ION and topical-dural capsaicin application (CCI-ION + Capsaicin) group. Behavioral testing and immunohistochemical staining were performed.

Results

In the behavioral test, the Sham + Capsaicin group showed significantly longer duration of immobilization and shorter duration of exploration compared with the Sham + Vehicle group, which is similar to clinical features of migraine patients. Moreover, CCI-ION enhanced these effects in the CCI-ION + Capsaicin group. Immunohistochemical staining for phospho-extracellular signal-related kinase (pERK) in the trigeminal ganglion (TG) containing first and second divisions of the trigeminal nerve and the trigeminocervical complex (TCC) revealed that pERK expression was significantly increased in the CCI-ION + Capsaicin group compared with the other groups. However, comparing between effects of the peripheral and central sensitizations (in the TG and TCC), from our results, peripheral sensitization would play a much less or not significant role.

Conclusions

These data demonstrate that the sensitization of V2 could influence the activation and the sensitization of the first division of the trigeminal nerve in the TCC, subsequently exacerbating pain sensation and pain-related behaviors. We have shown for the first time that the existence of the central sensitization of V2 can be an exacerbating factor for migraine related nociceptive thresholds/activation.

Prevalence of lifetime depression in a large hemiplegic migraine cohort

OBJECTIVE

To determine the prevalence of depression and determinants associated with depression in a large population of hemiplegic migraine (HM) patients.

METHODS

We conducted a cross-sectional, validated questionnaire study among 89 well-defined HM patients and 235 headache-free controls. The prevalence of lifetime depression and its relation to migraine characteristics was assessed.

RESULTS

HM patients had increased odds for lifetime depression (odds ratio 3.73, 95% confidence interval 2.18-6.38) compared with controls. Use of acute antimigraine medication was associated with lifetime depression.

CONCLUSIONS

Depression is part of the monogenic hemiplegic migraine phenotype. Further studies are needed to elucidate the pathophysiologic role of HM genes in comorbid depression. For now, clinicians should take comorbid depression into consideration when starting prophylactic treatment of HM.

Activation of the nuclear factor E2-related factor 2/anitioxidant response element alleviates the nitroglycerin-induced hyperalgesia in rats

Background

Antioxidants have been proven to weaken hyperalgesia in neuropathic pain. Endogenous antioxidant defense system may have a role in the prevention of hyperalgesia in migraine. In this study, we aimed to evaluate the role of nuclear factor E2-related factor 2/antioxidant response element (Nrf2/ARE) pathway in regulating the activation of the trigeminovascular system (TGVS) and hypersensitivity in nitroglycerin (NTG)-induced hyperalgesia rats.

Methods

The expression levels of Nrf2, HO, HO1, and NQO1 in the trigeminal nucleus caudalis (TNC) were detected by western blot. Immunofluorescence was used to demonstrate the cell-specific localization of Nrf2 in TNC. Sulforaphane, a Nrf2 activator, was administered to NTG-induced rats. Then, the number of c-Fos- and nNOS-immunoreactive neurons in TNC was evaluated using immunofluorescence, and c-Fos and nNOS protein levels were quantified using western blot. Von Frey hair testing was used to evaluate the tactile thresholds of rats at different time points in different groups.

Results

Total cellular and nuclear levels of the proteins Nrf2, HO1, and NQO1 were elevated in TNC after NTG injection, and Nrf2 was found to be located in the nucleus and cytoplasm of the neurons. Sulforaphane pretreatment significantly increased the nuclear Nrf2, HO1, and NQO1 levels in TNC. In addition, sulforaphane exposure effectively inhibited the expression of nNOS and c-Fos, reduced the number of nNOS and c-Fos immunoreactive neurons in TNC, and attenuated the tactile thresholds induced by NTG injection.

Conclusion

Oxidative stress was involved in nitroglycerin-induced hyperalgesia. Activation of the Nrf2/ARE pathway inhibited the activation of TGVS and prevented the induction of hyperalgesia. Sulforaphane might therefore be an effective agent for hyperalgesia. Further studies are needed to discover the underlying mechanisms of the process.

Deficient prepulse inhibition of blink reflex in migraine and its relation to allodynia

OBJECTIVE

Prepulse inhibition (PPI) of the blink reflex (BR) is a reduction in BR excitability due to a conditioning stimulus, reflecting sensory gating by brainstem structures. We aimed to analyze PPI changes during a painful episode in chronic or episodic migraine and its relation to allodynia, since abnormal brainstem filtering has been hypothesized in migraine pathophysiology.

METHODS

We included 20 patients with migraine during headache episode, and age- and gender-matched 22 healthy subjects. We recorded BR after unconditioned and conditioned supraorbital stimuli. For conditioned stimuli, we applied preceding subthreshold stimulus to the median nerve at wrist. The presence of PPI was compared between the two groups, as well as the specific BR parameters (latency, amplitude or area of R1 and R2 components) in unconditioned (test) and conditioned (PPI) paradigms.

RESULTS

In the patient group, seven (35%) patients did not have R2-PPI whereas all healthy subjects had R2-PPI (P=0.003). Healthy subjects displayed significantly increased R1 amplitude and reduced R2 amplitude and area after conditioned stimuli. In migraine patients, we observed significant reduction only in R2 amplitude. Logistic regression demonstrated that allodynia was independently related with the presence of PPI (beta: -0.535, P=0.021).

CONCLUSIONS

Our study provides evidence for sensory gating impairment at brainstem level in migraine headache, related to the presence of allodynia.

Association of depressive symptoms with allodynia in patients with migraine: A cross-sectional study

Aims

Migraine and depression have a strong association. We aimed to determine whether this relationship was particularly evident in migraineurs with allodynia.

Methods

A cross-sectional study was carried out of 98 consecutive patients with episodic migraine presenting for their first evaluation in an outpatient clinic. The participants completed a demographic questionnaire, the Allodynia Symptom Checklist and the Hospital Anxiety and Depression Scale (HADS).

Results

Among the migraineurs, 75 (77%) reported allodynia. Allodynia was associated with higher median HADS-Anxiety (9 vs. 6, p = 0.038) and HADS-Depression (6 vs. 4, p = 0.014) scores. In a multiple regression model, the HADS-Depression scores were independently associated with allodynia (odds ratio 1.236, 95% confidence interval 1.046–1.461). An increased severity of allodynia correlated with higher depression scores ( r = 0.224; p = 0.027).

Conclusion

Anxious and depressive symptoms are more common in migraineurs with allodynia than in those without allodynia. Further studies are necessary to clarify the relationship between depressive symptoms and allodynia, as well as its therapeutic implications in migraine.

Chronic migraine: risk factors, mechanisms and treatment

Chronic migraine has a great detrimental influence on a patient's life, with a severe impact on socioeconomic functioning and quality of life. Chronic migraine affects 1-2% of the general population, and about 8% of patients with migraine; it usually develops from episodic migraine at an annual conversion rate of about 3%. The chronification is reversible: about 26% of patients with chronic migraine go into remission within 2 years of chronification. The most important modifiable risk factors for chronic migraine include overuse of acute migraine medication, ineffective acute treatment, obesity, depression and stressful life events. Moreover, age, female sex and low educational status increase the risk of chronic migraine. The pathophysiology of migraine chronification can be understood as a threshold problem: certain predisposing factors, combined with frequent headache pain, lower the threshold of migraine attacks, thereby increasing the risk of chronic migraine. Treatment options include oral medications, nerve blockade with local anaesthetics or corticoids, and neuromodulation. Well-defined diagnostic criteria are crucial for the identification of chronic migraine. The International Headache Society classification of chronic migraine was recently updated, and now allows co-diagnosis of chronic migraine and medication overuse headache. This Review provides an up-to-date overview of the classification of chronic migraine, basic mechanisms and risk factors of migraine chronification, and the currently established treatment options.

Clinically relevant behavioral endpoints in a recurrent nitroglycerin migraine model in rats

BACKGROUND

This research sought to further validate the rat nitroglycerin (NTG) migraine model by comparing the effects of single versus recurrent NTG episodes on behavioral endpoints that mirror ICHD-3 diagnostic criteria for migraine, and to determine if the altered behavioral endpoints are reduced after administration of sumatriptan.

METHODS

Separate cohorts of rats were administered NTG (10 mg/kg/2 ml) or saline (Experiment 1: single injection; Experiment 2: repeated injections; Experiment 3: repeated injections with sumatriptan [0.0, 0.3 and 1.0 mg/kg/ml] rescue. Behavioral endpoints were assessed 2 h after final NTG administration and included time in light/dark chambers for photophobia and activity, pain facial ratings, and cool (5 °C) and warm (46 °C) tail dip.

RESULTS

The first two experiments demonstrated that repeated (n = 5) but not single NTG injections produced photophobia, decreased activity, and yielded less weight gain than saline injections. Experiment 3 showed that sumatriptan attenuated hypoactivity, reduced facial expressions of pain, and reversed weight alterations in a dose-dependent manner.

CONCLUSIONS

These findings identify numerous clinical homologies of a recurrent NTG rat migraine model that may be useful for screening novel pharmacotherapies.

Functional interictal changes of pain processing in migraine with ictal cutaneous allodynia

Objective

A prospective clinical imaging study has been conducted to investigate pain processing functional pathways during trigeminal heat stimulation (THS) in patients with migraine without aura experiencing ictal cutaneous allodynia (CA) (MwoA CA+).

Methods

Using whole-brain BOLD-fMRI, functional response to THS at three different intensities (41°, 51° and 53℃) was investigated interictally in 20 adult MwoA CA+ patients compared with 20 MwoA patients without ictal CA (MwoA CA−) and 20 healthy controls (HCs). Secondary analyses evaluated associations between BOLD signal change and clinical features of migraine.

Results

During moderate-noxious THS (51℃), we observed a significantly greater activation in (a) the anterior cingulate cortex in MwoA CA+ patients compared to HCs and (b) the middle frontal gyrus in MwoA CA+ patients compared to both MwoA CA− patients and HCs. Furthermore, during high-noxious THS (53℃) a significantly decreased activation in the secondary somatosensory cortices was observed in (a) MwoA CA− patients compared to both MwoA CA+ patients and HCs and (b) MwoA CA+ patients compared to HCs. CA severity was positively correlated with the secondary somatosensory cortices activation.

Conclusions

Our findings suggest that CA may be subtended by both a dysfunctional analgesic compensatory mechanism and an abnormal internal representation of pain in migraine patients.

Altered effective connectivity of posterior thalamus in migraine with cutaneous allodynia: a resting-state fMRI study with Granger causality analysis

BACKGROUND

Most migraineurs develop cutaneous allodynia (CA) during migraine, and the underlying mechanism of CA in migraine is thought to be sensitization of the third-order trigeminovascular neurons in the posterior thalamic nuclei. This study aimed to investigate whether the ascending/descending pathway associated with the thalamus is disturbed in migraineurs with CA (MWCA) using effective connectivity analysis of resting-state functional magnetic resonance imaging.

METHODS

Thirty four migraineurs without aura (14 MWCA and 20 migraineurs without CA (MWoCA)) and 25 matched healthy controls (HC) were recruited in the study. The effective connectivity pathways associated with the posterior thalamus (PTH) were investigated using the Granger causality analysis. We chose bilateral PTH as two individual seeds, and compared MWCA with MWoCA and HC, respectively. Spearman correlation analysis was performed to test the correlation between the abnormal effective connectivity and the allodynia severity of MWCA.

RESULTS

Compared with MWoCA, MWCA showed decreased inflows from the left limbic regions and dorsal medial prefrontal cortex (dmPFC) to the ipsilateral PTH, as well as increased inflow from the right ventral medial prefrontal cortex (vmPFC) to the ipsilateral PTH; no significantly different outflows from the bilateral PTH to other regions were found. Compared with HC, MWCA showed increased outflows from the left PTH to the bilateral vmPFC, decreased outflows from the right PTH to the bilateral temporoparietal areas, decreased inflow from the left parietooccipital area to the ipsilateral PTH, and increased inflows from the right dorsolateral prefrontal cortex and the bilateral temporoparietal areas to the right PTH. Correlation analyses revealed that the disturbed connectivities between PTH and cuneus, as well as PTH and middle frontal gyrus were associated with the allodynia severity of MWCA.

CONCLUSIONS

MWCA demonstrated disrupted effective connection pathways between the PTH and other cortical or subcortical regions that participated in multi-dimentional pain processing. Our findings highlight the dysfunctional ascending and descending pain network at the thalamic-level and may help to illuminate the possible pathophysiologic mechanisms of CA.

A touchy subject: an assessment of cutaneous allodynia in a chronic migraine population

Background

Cutaneous allodynia (CA) is a common feature of migraine, which has a complex underlying pathophysiology that is not well understood. In addition to pain, photophobia, phonophobia, osmophobia, nausea, and vomiting, CA can contribute to the overall disability caused by migraine. The presence of CA can be established via a validated questionnaire. Validated questionnaires and other tests are rarely performed in clinical practice. As such, current prevalence estimates for CA may be an underestimation.

Methods

Utilizing a validated questionnaire, we assessed the presence of CA in consecutive patients (n=44) presenting with chronic migraine at a tertiary headache center.

Results

CA appears to be quite prevalent, at ~90%, among female patients with chronic migraine.

Conclusion

CA prevalence in chronic migraine may be underestimated in the literature, and larger studies may better demonstrate a more accurate estimate of its prevalence.

The role of intracranial hypertension in the chronification of migraine

Besides a similar clinical presentation, idiopathic intracranial hypertension (IIH) and chronic migraine (CM) also share relevant risk factors, show a higher prevalence of allodynic symptoms and both respond to topiramate. Moreover, sinus stenosis, a radiological marker of IIH, in CM patients is much more prevalent than expected. As a consequence of these striking similarities, IIH without papilledema (IIHWOP) may be easily misdiagnosed as CM. Actually, IIHWOP has been found in up to 14 % of CM clinical series. Considering that, on one hand, an asymptomatic sinus stenosis-associated raised intracranial pressure (ICP) may be highly prevalent in the general population, and on the other, that IIH clinical presentation with chronic headache may require a migraine predisposition, we have proposed that an overlooked IIHWOP could represent a risk factor for migraine progression. This hypothesis prompted us to investigate the prevalence of IIHWOP and its possible role in the process of migraine chronification in a consecutive series of CM patients selected for unresponsiveness to medical treatment and evidence of significant sinus stenosis. The main finding of our study is that the large majority of such patients actually suffer from a chronic headache secondary to IIHWOP. This implies that an IIHWOP mimicking CM is much more prevalent than believed, is commonly misdiagnosed as CM on the basis of ICHD criteria and is strictly predicted by refractoriness to preventive treatments. However, our data fully comply with the alternative hypothesis that an overlooked IIHWOP, although highly prevalent amongst healthy individuals, in migraine-prone subjects is a powerful (and modifiable) risk factor for the progression and the refractoriness of pain. The normalization of ICP by even a single LP with CSF withdrawal may be effective in a significant proportion of patients with a long history of refractory chronic headache, who represent about one-fifth of the patients screened in our study. We suggest that IIHWOP should be considered in all patients with almost daily migraine pain, with evidence of sinus stenosis and unresponsive to medical treatment, referred to specialized headache clinics.

Evidence-Based Treatments for Adults with Migraine

Migraine, a significantly disabling condition, is treated with acute and preventive medications. However, some individuals are refractory to standard treatments. Although there is a host of alternative management options available, these are not always backed by strong evidence. In fact, most of the drugs used in migraine were initially designed for other purposes. Whilst effective, the benefits from these medications are modest, reflecting the need for newer and migraine-specific therapeutic agents. In recent years, we have witnessed the emergence of novel treatments, of which noninvasive neuromodulation appears to be the most attractive given its ease of use and excellent tolerability profile. This paper reviews the evidence behind the available treatments for migraine.

Functional Connectivity of EEG Signals Under Laser Stimulation in Migraine

In previous studies, migraine patients showed abnormalities in pain-related evoked responses, as reduced habituation to repetitive stimulation. In this study, we aimed to apply a novel analysis of EEG bands synchronization and directed dynamical influences under painful stimuli in migraine patients compared to non-migraine healthy volunteers. Thirty-one migraine without aura outpatients (MIGR) were evaluated and compared to 19 controls (CONT). The right hand was stimulated by means of 30 consecutive CO₂ laser stimuli. EEG signal was examined by means of Morlet wavelet, synchronization entropy (SE), and Granger causality (GC), and the statistically validated results were mapped on the corresponding scalp locations. The vertex complex of averaged laser-evoked responses (LEPs) showed reduced habituation compared to CONT. In the prestimulus phase, enhanced SE in the 0, 5–30 Hz range was present in MIGR and CONT between the bilateral temporal–parietal and the frontal regions around the midline. Migraine patients showed an anticipation of EEG changes preceding the painful stimulation compared to CONT. In the poststimulus phase, the same cortical areas were more connected in MIGR vs CONT. In both groups of patients and CONT, the habituation index was negatively correlated with the GC scores. A different pattern of cortical activation after painful stimulation was present in migraine. The increase in cortical connections during repetitive painful stimulation may subtend the phenomenon of LEPs reduced habituation. Brain network analysis may give an aid in understanding subtle changes of pain processing under laser stimuli in migraine patients.

Symptom dimensions of affective disorders in migraine patients

OBJECTIVE

A strong association has been established between migraine and depression. However, this is the first study to differentiate in a large sample of migraine patients for symptom dimensions of the affective disorder spectrum.

METHODS

Migraine patients (n=3174) from the LUMINA (Leiden University Medical Centre Migraine Neuro-analysis Program) study and patients with current psychopathology (n=1129), past psychopathology (n=477), and healthy controls (n=561) from the NESDA (Netherlands Study of Depression and Anxiety) study, were compared for three symptom dimensions of depression and anxiety. The dimensions -lack of positive affect (depression specific); negative affect (nonspecific); and somatic arousal (anxiety specific)- were assessed by a shortened adaptation of the Mood and Anxiety Symptom Questionnaire (MASQ-D30). Within the migraine group, the association with migraine specific determinants was established. Multivariate regression analyses were conducted.

RESULTS

Migraine patients differed significantly (p<0.001) from healthy controls for all three dimensions: Cohen's d effect sizes were 0.37 for lack of positive affect, 0.68 for negative affect, and 0.75 for somatic arousal. For the lack of positive affect and negative affect dimensions, migraine patients were predominantly similar to the past psychopathology group. For the somatic arousal dimension, migraine patients scores were more comparable with the current psychopathology group. Migraine specific determinants for high scores on all dimensions were high frequency of attacks and cutaneous allodynia during attacks.

CONCLUSION

This study shows that affective symptoms in migraine patients are especially associated with the somatic arousal component.

Risk factors of chronic daily headache or chronic migraine

Chronic daily headache (CDH) is a common neurological condition that affects 1-4 % of the general population. Most individuals with CDH originally suffered from episodic headaches, but over time, this developed into CDH. Although the pathophysiology of CDH is not fully understood, recent clinical and epidemiological studies suggest some risk factors that are associated with an increased risk of transformation from episodic headaches. If risk factors can be identified, they could provide a base for aggressive preventive intervention and thus decrease the transformation from episodic headaches to eventual CDH. In this article, we review and summarize the current data on risk factors for CDH.

Laser-evoked potential habituation and central sensitization symptoms in childhood migraine

Objectives

Few studies have addressed central sensitization symptoms and pain processing in childhood migraine. Our aims were to examine pain sensitivity and responses, including habituation, evoked by CO2 laser stimuli (laser-evoked potentials (LEPs)) in a cohort of children with migraine compared to non-migraine controls and to determine the correlation between LEP features and signs of central sensitization.

Methods

Thirty-five patients 8–15 years of age with migraines without aura were evaluated during the inter-critical phase and were compared to 17 controls. LEPs were analyzed, and their main features were correlated with clinical symptoms including allodynia and pericranial tenderness.

Results

The laser-evoked pain threshold was lower and the N2P2 vertex complex amplitude was higher in children with migraines. Furthermore, habituation of vertex waves of LEPs clearly showed a tendency toward progressive amplitude enhancement in the migraine group. Acute allodynia and inter-critical pericranial tenderness correlated with trigeminal LEP features, particularly with the abnormal habituation pattern.

Discussion

Abnormalities of pain processing and symptoms of central sensitization appear to be characteristics of children with migraine. Reduced habituation and progressive amplification of cortical responses to laser stimuli indicate an overactive nociceptive system at the onset of migraine, and this hyperactivity may subtend allodynia and pericranial tenderness. Future prospective trials may aid in the early identification of clinical phenotypes that display a tendency to develop into the chronic form of migraine, warranting a timely therapeutic approach.

Treatment of Chronic Migraine with OnabotulinumtoxinA: Mode of Action, Efficacy and Safety

Background: Chronic migraine is a common, highly disabling, underdiagnosed and undertreated entity of migraine. It affects 0.9%–2.2% of the general adult population. The present paper overviews the preclinical and clinical data regarding the therapeutic effect of onabotulinumtoxinA in chronic migraineurs. Methods: A literature search was conducted in the database of PubMed up to 20 May 2015 for articles related to the pathomechanism of chronic migraine, the mode of action, and the efficacy, safety and tolerability of onabotulinumtoxinA for the preventive treatment of chronic migraine. Results: The pathomechanism of chronic migraine has not been fully elucidated. The mode of action of onabotulinumtoxinA in the treatment of chronic migraine is suggested to be related to the inhibition of the release of calcitonin gene-related peptide and substance P in the trigeminovascular system. Randomized clinical trials demonstrated that long-term onabotulinumtoxinA fixed-site and fixed-dose (155–195 U) intramuscular injection therapy was effective and well tolerated for the prophylactic treatment of chronic migraine. Conclusions: Chronic migraine is a highly devastating entity of migraine. Its exact pathomechanism is unrevealed. Two-third of chronic migraineurs do not receive proper preventive medication. Recent clinical studies revealed that onabotulinumtoxinA was an efficacious and safe treatment for chronic migraine.

OnabotulinumtoxinA for chronic migraine: a critical appraisal

Chronic migraine (CM) is a severe disabling condition with a few available evidence-based management options. OnabotulinumtoxinA (onaBoNTA) is approved for use in a number of disorders. Its benefits and potential use in migraine were observed incidentally while treating patients cosmetically for wrinkles. The mechanism of action of onaBoNTA in CM is not fully understood, but there is evidence that this involves axonal transport via sensory fibers. The Phase III REsearch Evaluating Migraine Prophylaxis Therapy trials have established the efficacy as well as the long-term safety and tolerability of onaBoNTA in CM. This review will discuss the evidence behind its use in this setting.

Clinical Pain Catastrophizing in Women With Migraine and Obesity

OBJECTIVE/BACKGROUND

Obesity is related to migraine. Maladaptive pain coping strategies (eg, pain catastrophizing) may provide insight into this relationship. In women with migraine and obesity, we cross-sectionally assessed: (1) prevalence of clinical catastrophizing; (2) characteristics of those with and without clinical catastrophizing; and (3) associations of catastrophizing with headache features.

METHODS

Obese women migraineurs seeking weight loss treatment (n = 105) recorded daily migraine activity for 1 month via smartphone and completed the Pain Catastrophizing Scale (PCS). Clinical catastrophizing was defined as total PCS score ≥30. The six-item Headache Impact Test (HIT-6), 12-item Allodynia Symptom Checklist (ASC-12), Headache Management Self-Efficacy Scale (HMSE), and assessments for depression (Centers for Epidemiologic Studies Depression Scale) and anxiety (seven-item Generalized Anxiety Disorder Scale) were also administered. Using PCS scores and body mass index (BMI) as predictors in linear regression, we modeled a series of headache features (ie, headache days, HIT-6, etc) as outcomes.

RESULTS

One quarter (25.7%; 95% confidence interval [CI] = 17.2-34.1%) of participants met criteria for clinical catastrophizing: they had higher BMI (37.9 ± 7.5 vs 34.4 ± 5.7 kg/m(2) , P = .035); longer migraine attack duration (160.8 ± 145.0 vs 97.5 ± 75.2 hours/month, P = .038); higher HIT-6 scores (68.7 ± 4.6 vs 64.5 ± 3.9, P < .001); more allodynia (7.0 ± 4.1 vs 4.5 ± 3.5, P < .003), depression (25.4 ± 12.4 vs 13.3 ± 9.2, P < .001), and anxiety (11.0 ± 5.2 vs 5.6 ± 4.1, P < .001); and lower self-efficacy (80.1 ± 25.6 vs 104.7 ± 18.9, P < .001) compared with participants without clinical catastrophizing. The odds of chronic migraine were nearly fourfold greater in those with (n = 8/29.6%) vs without (n = 8/10.3%) clinical catastrophizing (odds ratio = 3.68; 95%CI = 1.22-11.10, P = .021). In all participants, higher PCS scores were related to more migraine days (β = 0.331, P = .001), longer attack duration (β = 0.390, P < .001), higher HIT-6 scores (β = 0.425, P < .001), and lower HMSE scores (β = -0.437, P < .001). Higher BMI, but not higher PCS scores, was related to more frequent attacks (β = -0.203, P = .044).

CONCLUSIONS

One quarter of participants with migraine and obesity reported clinical catastrophizing. These individuals had more frequent attacks/chronicity, longer attack duration, higher pain sensitivity, greater headache impact, and lower headache management self-efficacy. In all participants, PCS scores were related to several migraine characteristics, above and beyond the effects of obesity. Prospective studies are needed to determine sequence and mechanisms of relationships between catastrophizing, obesity, and migraine.

Osmophobia and allodynia are critical factors for suicidality in patients with migraine

Background

Sensory hypersensitivities are common phenomena in migraine. We examined the role of sensory hypersensitivities on suicidality in patients with migraine.

Methods

Patients with migraine (with or without aura) were consecutively recruited from our headache clinic. We asked them if they experienced photophobia, phonophobia, osmophobia, and allodynia during migraine attack. The Mini International Neuropsychiatric Interview was used to diagnose current major depressive disorder (MDD), current generalized anxiety disorder (GAD) and suicidality.

Results

Among 220 subjects, 25.5 % had current MDD, 17.3 % had current GAD, and 31.8 % had suicidality. Patients with suicidality were more like to have a low household income, chronic migraine (CM), medication overuse headache, high headache intensity, osmophobia, allodynia, high disability, MDD, and GAD than those without suicidality. The strongest risk factor for suicidality by multivariate analyses was osmophobia (adjusted Odds Ratio [AOR] 3.12, 95 % confidence interval [CI] 1.57-6.21, p = 0.001), followed by current MDD (AOR 2.99, 95 % CI 1.33-6.76, p = 0.008), CM (AOR 2.48, 95 % CI 1.21-5.09, p = 0.013), current GAD (AOR 3.11, 95 % CI 1.22-7.91, p = 0.017), and allodynia (AOR 2.72, 95 % CI 1.19-6.21, p = 0.018).

Conclusions

Osmophobia and allodynia are critical factors for suicidality in patients with migraine, after controlling for depression, anxiety, and CM.

Cooperativity between remote sites of ectopic spiking allows afterdischarge to be initiated and maintained at different locations

Many symptoms of nerve damage arise from ectopic spiking caused by hyperexcitability. Ectopic spiking can originate at the site of axonal damage and elsewhere within affected neurons. This raises the question of whether localized damage elicits cell-wide changes in excitability and/or if localized changes in excitability can drive abnormal spiking at remote locations. Computer modeling revealed an example of the latter involving afterdischarge (AD)--stimulus-evoked spiking that outlasts stimulation. We found that AD originating in a hyperexcitable region of axon could shift to the soma where it was maintained. This repositioning of ectopic spike initiation was independent of distance between the two sites but relied on the rate and number of ectopic spikes originating from the first site. Nonlinear dynamical analysis of a reduced model demonstrated that properties which rendered the axonal site prone to initiating AD discouraged it from maintaining AD, whereas the soma had the inverse properties thus enabling the two sites to interact cooperatively. A first phase of AD originating in the axon could, by providing sufficient drive to trigger somatic AD, give way to a second phase of AD originating in the soma such that spiking continued when axonal AD failed. Ectopic spikes originating from the soma during phase 2 AD propagated successfully through the defunct site of axonal spike initiation. This novel mechanism whereby ectopic spiking at one site facilitates ectopic spiking at another site is likely to contribute to the chronification of hyperexcitability in conditions such as neuropathic pain.

Role of phosphorylated extracellular signal-regulated kinase, calcitonin gene-related peptide and cyclooxygenase-2 in experimental rat models of migraine

Although migraine is a common neurological condition, the pathomechanism is not yet fully understood. Activation of the trigeminovascular system (TVS) has an important function in this disorder and neurogenic inflammation and central sensitization are important mechanisms underlying this condition. Nitroglycerin (NTG) infusion in rats closely mimics a universally accepted human model of migraine. Electrical stimulation of the trigeminal ganglion (ESTG) of rats can also activate TVS during a migraine attack. Numerous studies have revealed that phosphorylated extracellular signal-regulated kinase (p-ERK), calcitonin gene-related peptide (CGRP) and cyclooxygenase-2 (COX-2) are involved in pain and nociceptive pathways. However, few studies have examined whether p-ERK, CGRP and COX-2 are involved in neurogenic inflammation and central sensitization. In the present study, the expression of p-ERK, CGRP and COX-2 was detected in the dura mater, trigeminal ganglion (TG) and spinal trigeminal nucleus caudalis in NTG-induced rats and ESTG models by immunohistochemistry. The three areas considered were crucial components of the TVS. The selective COX-2 inhibitor nimesulide was used in ESTG rats to examine the association between p-ERK, CGRP and COX-2. The results demonstrated that p-ERK, CGRP and COX-2 mediated neurogenic inflammation and central sensitization in migraine. In addition, the expression of p-ERK and CGRP was attenuated by the COX-2 inhibitor.

Diagnosis, pathophysiology and management of chronic migraine: a proposal of the Belgian Headache Society

Chronic migraine (CM) is a disabling neurological condition affecting 0.5-2 % of the population. In the current third edition of the International Classification of Headache Disorders, medication overuse is no longer an exclusion criterion and CM is diagnosed in patients suffering from at least 15 headache days per month of which at least eight are related to migraine. CM is difficult to treat, and preventive treatment options are limited. We provide a pathogenetic model for CM, integrating the latest findings from neurophysiological and neuroimaging studies. On behalf of the Belgian Headache Society, we present a management algorithm for CM based on the international literature and adapted to the Belgian situation. Pharmacological treatment options are discussed, and recent data on transcranial and invasive neuromodulation studies in CM are reviewed. An integrated multimodal treatment programme may be beneficial to refractory patients, but at present, this approach is only supported by a limited number of observational studies and quite variable between centres.

Low cognitive reserve is associated with chronic migraine with medication overuse and poor quality of life

Objective

The objective of this article is to test the hypothesis that cognitive reserve (CR) is related to migraine chronification, medication overuse and poor quality of life in migraineurs.

Design/methods

A cross-sectional study on patients with chronic migraine with medication overuse (CM-MOH), episodic migraine (EM), and controls, matched by sex, age and education, was carried out. CR was assessed by a specific questionnaire, and quality of life was measured by general and specific questionnaires (SF-36 and MSQoL). Migraine Disability Assessment Scale and Beck questionnaires for depression and anxiety were used. Medication dependence was evaluated by the medication-dependence questionnaire in headache (MDQ-H).

Results

Fifty-five individuals were enrolled: 18 CM-MOH patients (32.73%), 22 EM patients (40%) and 15 controls (27.27%). Fifty (90.91%) of them were females and aged 43.53 (7.54) years. Univariate analysis showed a significant association between the study group and CR, and all items of the SF-36, anxiety and depression questionnaires, MSQoL and MDQ-H. The lower CR and CM-MOH group were related to a worse quality of life, more anxiety and depression and the highest medication dependence scores. Multivariate analysis showed that higher CR scores were related to higher quality of life as measured by the physical and mental composite scores of the SF-36, and to lower anxiety (beta = −1.08, p = 0.001) and depression (beta = −0.56, p = 0.03) levels. Focusing on MSQoL, the increase in CR was predictive of a better quality of life (beta = 1.88, p < 0.0001). By all the models, the explained variance of the sample ranged from 39% (mental composite score) to 58% (MSQoL).

Conclusions

Low CR appears to be an independent factor associated with the deterioration of quality of life, the presence of anxiety and depression, and drug dependence and medication overuse in CM-MOH.

Sleep features and central sensitization symptoms in primary headache patients

BACKGROUND

Association between sleep disorders and headache is largely known. The aim of the present study was to evaluate sleep quality and quantity in a large cohort of primary headache patients, in order to correlate these scores with symptoms of central sensitization as allodynia, pericranial tenderness and comorbidity with diffuse muscle-skeletal pain.

METHODS

One thousand six hundreds and seventy primary headache out patients were submitted to the Medical Outcomes Study (MOS) within a clinical assessment, consisting of evaluation of frequency of headache, pericranial tenderness, allodynia and coexistence of fibromyalgia syndrome (FM).

RESULTS

Ten groups of primary headache patients were individuated, including patients with episodic and chronic migraine and tension type headache, mixed forms, cluster headache and other trigeminal autonomic cephalalgias. Duration but not sleep disturbances score was correlated with symptoms of central sensitization as allodynia and pericranial tenderness in primary headache patients. The association among allodynia, pericranial tenderness and short sleep characterized chronic migraine more than any other primary headache form. Patients presenting with FM comorbidity suffered from sleep disturbances in addition to reduction of sleep duration.

CONCLUSION

Self reported duration of sleep seems a useful index to be correlated with allodynia, pericranial tenderness and chronic headache as a therapeutic target to be assessed in forthcoming studies aiming to prevent central sensitization symptoms development.

Candidate-gene association study searching for genetic factors involved in migraine chronification

INTRODUCTION

Chronic migraine (CM) is at the severe end of the clinical migraine spectrum, but its genetic background is unknown. Our study searched for evidence that genetic factors are involved in the chronification process.

METHODS

We initially selected 144 single-nucleotide polymorphisms (SNPs) from 48 candidate genes, which we tested for association in two stages: The first stage encompassed 262 CM patients, the second investigated 226 patients with high-frequency migraine (HFM). Subsequently, SNPs with p values < 0.05 were forwarded to the replication stage containing 531 patients with CM or HFM.

RESULTS

Eight SNPs were significantly associated with CM and HFM in the two-stage phase. None survived replication in the third stage.

DISCUSSION

We present the first comprehensive genetic association study for migraine chronification. There were no significant findings. Future studies may benefit from larger, genome-wide data sets or should use other genetic approaches to identify genetic factors involved in migraine chronification.

Allodynia is associated with a higher prevalence of depression in migraine patients

Introduction

There is a strong association between migraine and depression. The aim of this study is to identify migraine-specific factors involved in this association.

Methods

We conducted a cross-sectional study in a large, well-defined cohort of migraine patients ( n = 2533). We assessed lifetime depression using validated questionnaires, and diagnosed migraine based on the International Classification of Headache Disorders III-beta criteria. Multivariate regression analyses were conducted.

Results

Of the 2533 migraineurs that were eligible, 1137 (45%) suffered from lifetime depression. The following independent factors were associated with an increased depression prevalence: i) migraine-specific risk factors: high migraine attack frequency and the presence of allodynia, ii) general factors: being a bad sleeper, female gender, high BMI, being single, smoking, and a low alcohol consumption.

Conclusion

This study identified allodynia, in addition to high migraine attack frequency, as a new migraine-specific factor associated with depression.

Tackling chronic migraine: current perspectives

In the last decade, several diagnostic criteria and definitions have been proposed for chronic migraine (CM). The third edition of the International Classification of Headache Disorders–3 beta, published in 2013, has revised CM diagnostic criteria. CM is defined as “headache occurring on 15 or more days per month for more than 3 months, which has the features of migraine headache on at least 8 days per month.” Patients who meet the criteria for CM and for medication-overuse headache should be given both diagnoses. Worldwide, CM prevalence ranges 1%–3%, and its incidence has been estimated to be 2.5% per year. CM is associated with disability and poor quality of life. Modifiable risk factors include (among others): migraine progression (defined as an increase in frequency and severity of migraine attacks); medication and caffeine overuse; obesity; stressful life events; and snoring. CM patients have a significantly higher frequency of some comorbid conditions, including chronic pain, psychiatric disorders, respiratory illness, and some vascular risk factors. Management includes identification and control of comorbidities and risk factors that predispose to CM; treatment and prevention for medication overuse; early treatment for migraine attacks; and an adequate preventive therapy for CM. Several randomized controlled clinical trials have shown the efficacy of topiramate, amitriptyline, onabotulinumtoxinA, and cognitive-behavioral therapy in CM.

General trigeminospinal central sensitization and impaired descending pain inhibitory controls contribute to migraine progression

Migraine is a chronic disease with episodic manifestations. In a subgroup, attack frequency increases over time, leading to chronic migraine. One of the most important risk factors for migraine progression is frequency of headache attacks at baseline. Unfortunately, the actual effects of repeated activation of dural nociceptors are poorly known. We investigated the behavioral, anatomical, and electrophysiological changes induced by repeated low- and high-intensity stimulation of meningeal nociceptor by injecting an inflammatory soup in rats. Single high-intensity, but not low-intensity, stimulation produces a reversible cephalic allodynia. Upon repetition, however, low-intensity stimulation, too, induces a reversible cephalic allodynia, and high-intensity, reversible cephalic and extracephalic allodynia. Moreover, cephalic allodynia becomes, in part, persistent upon repeated high-intensity stimulation. Fos expression reveals that a single high-intensity stimulation already leads to widespread, trigeminal, and spinal central sensitization, and that such general central sensitization potentiates upon repetition. Trigeminovascular nociceptive neurons become persistently sensitized and their diffuse noxious inhibitory controls (DNIC) concomitantly impaired. Thus, compared with single stimulation, repeated dural nociceptor activation specifically leads to: 1) a gradual worsening of cutaneous hypersensitivity and general neuronal hyperexcitability and 2) spreading of cutaneous hypersensitivity superimposed on 3) persistent cephalic cutaneous hypersensitivity and trigeminal central sensitization. Such repetition-induced development of central sensitization and its consequence, cutaneous allodynia, may arise from both the general neuronal hyperexcitability that results from DNIC impairment and hyperexcitability that likely develops in trigeminal nociceptive neurons in response to their repetitive activation. These neuronal changes may in turn elevate the risk for developing chronic migraine.