From CGRP to PACAP, VIP, and Beyond: Unraveling the Next Chapters in Migraine Treatment.

Migraine is a neurovascular disorder that can be debilitating for individuals and society. Current research focuses on finding effective analgesics and management strategies for migraines by targeting specific receptors and neuropeptides. Nonetheless, newly approved calcitonin gene-related peptide (CGRP) monoclonal antibodies (mAbs) have a 50% responder rate ranging from 27 to 71.0%, whereas CGRP receptor inhibitors have a 50% responder rate ranging from 56 to 71%. To address the need for novel therapeutic targets, researchers are exploring the potential of another secretin family peptide, pituitary adenylate cyclase-activating polypeptide (PACAP), as a ground-breaking treatment avenue for migraine. Preclinical models have revealed how PACAP affects the trigeminal system, which is implicated in headache disorders. Clinical studies have demonstrated the significance of PACAP in migraine pathophysiology; however, a few clinical trials remain inconclusive: the pituitary adenylate cyclase-activating peptide 1 receptor mAb, AMG 301 showed no benefit for migraine prevention, while the PACAP ligand mAb, Lu AG09222 significantly reduced the number of monthly migraine days over placebo in a phase 2 clinical trial. Meanwhile, another secretin family peptide vasoactive intestinal peptide (VIP) is gaining interest as a potential new target. In light of recent advances in PACAP research, we emphasize the potential of PACAP as a promising target for migraine treatment, highlighting the significance of exploring PACAP as a member of the antimigraine armamentarium, especially for patients who do not respond to or contraindicated to anti-CGRP therapies. By updating our knowledge of PACAP and its unique contribution to migraine pathophysiology, we can pave the way for reinforcing PACAP and other secretin peptides, including VIP, as a novel treatment option for migraines.

[Neurosyphilis or not - a case of a differential diagnostic challenge]. / Neurosyphilis vagy nem ­ egy differenciáldiagnosztikai kihívás esete.

We report the case of a 42-year-old woman with paraparesis associated with transverse myelitis. For differential diagnostics detailed microbiological, cerebrospinal fluid (CSF) and neuroimaging examinations were performed. Syphilis was confirmed, but diagnosis of neurosyphilis was only probable based on the CSF microbiological test results. The beneficial treatment response to application of the therapeutic protocol for syphilis supported the supposed diagnosis of syphilis-associated myelitis in our case. In this case report we reviewed the differential diagnostic tools of myelopathies/myelitis.
Nowadays regarding to growing prevalence of syphilis worldwide physicians should face on its presence and medical consequences.

[Sumatriptan-naproxen sodium fix-dose combination for acute migraine treatment, a review]. / Szumatriptán­naproxén-nátrium fix dózisú kombinációja a migrén akut kezelésében ­ irodalmi áttekintés.

Migraine as a common primary headache disorder has a significant negative effect on quality of life of the patients. Its pharmacotreatment includes acute and preventative therapies. Based on the shared therapeutic guideline of the European Headache Federation and the European Academy of Neurology for acute migraine treatment a combination of triptans and non-steroidal anti-inflammatory drugs is recommended for acute migraine treatment in triptan-nonresponders. In this short review we summarized the results of the randomized controlled clinical trials evaluating the effectiveness and safety of sumatriptan (85 mg)/naproxen sodium (500 mg) fix-dose combination. It was revealed that the fix-dose combination was better than placebo for the primary outcomes of exemption of pain and headache relief at 2 hours. Furthermore the combination showed beneficial effect on accompanying symptoms of migraine attack (i.e. nausea, photo- and phonophobia). Adverse events were mild or moderate in severity and rarely led to withdrawal of the drug.
It can be concluded that sumatriptan (85 mg)/naproxen sodium (500 mg) fix-dose combination is effective, safe and well-tolerated in the acute treatment of migraine. 

[Headache registry in Szeged: Experiences regarding to migraine patients]. / Fejfájásregiszter kialakításával szerzett szegedi tapasztalataink migrénes betegek vonatkozásában.

Background and purpose:

Using patient registries is essential both in clinical research and in medical practice. Headaches, more specifically migraines are one of the most common complaints that can detract the quality of a patient’s life and these complaints also have a significant socio-econo­mic effect. Our goal is to create a national Headache Registry and to also provide the pre-analysis of the registry’s database.

Our research is based on the national Multiple Sclerosis Registry, which we modified using the latest version of diagnostic criteria published by the International Headache Society. This clinical study contains data collected from patients suffering from migraines and currently receiving care at the Headache Outpatient Department at the Neurologic Clinic of the University of Szeged.

The data of 412 patients (363 wo­men and 49 men) suffering from migraine (migraine without aura: n = 313 and migraine with aura: n = 99) were added to the Headache Registry. The average age of participants was 44.1 ± 12.5 SD years. Regarding the attributes of migraine headaches we examined the following characteristics: localization, quality and intensity (based on the Visual Analogue Scale) of the pain, frequency (the number of headache days per month), medications (acute or prophylactic), comorbidities (depression, anxiety, hypertension, asthma, epilepsy and others), family history and the occurrence of stroke among patients.

Based on international expe­rience, patient registries are the most optimal systems for structured patient mo­nitoring. For high level management and long-term follow up of the patients the application of registries is essential. The registries include the detailed medical history and the diagnostic and therapeutic data of the patients, and they trace the changes during the follow up medical visits. Registries are able to record the entire course of the disease in digital way. The numerous data can be set out any time from the digital database. Extensive spread of patients’ registries is fundamental not only in every day clinical practice, but also in clinical research.

The pharmacotherapeutic management of episodic and chronic migraine with gepants.

INTRODUCTION: The small molecule non-peptide calcitonin gene-related peptide (CGRP) receptor antagonists named gepants offer a breakthrough novel approach in migraine acute and prophylactic drug treatment. This review aimed to determine the place of gepants in the treatment of episodic and chronic migraine. AREAS COVERED: The new generation gepants are ubrogepant, atogepant, rimegepant, and zavegepant. Ubrogepant is ratified for acute migraine treatment, atogepant is validated for preventive therapy, whereas rimegepant is ratified for both indications, all via oral administration and while zavegepant is administered intranasally for migraine attacks. Gepants are effective, safe, and well-tolerated in acute or prophylactic therapy. The PubMed literature search included randomized controlled trials, meta-analyses, real-world data, and review articles published in English until January 2023. EXPERT OPINION: Whether gepants will be real game changers in the acute treatment of migraine compared to triptans and ditans or in the prophylactic therapy compared to standard-of-care preventive drugs or CGRP-targeting monoclonal antibodies cannot be answered yet based on the available literature data.

Cluster headache and kynurenines.

BACKGROUND: The glutamatergic neurotransmission has important role in the pathomechanism of primary headache disorders. The kynurenine metabolites derived from catabolism of tryptophan (Trp) have significant involvement not only in glutamatergic processes, but also in the neuroinflammation, the oxidative stress and the mitochondrial dysfunctions. Previously we identified a depressed peripheral Trp metabolism in interictal period of episodic migraineurs, which prompted us to examine this pathway in patients with episodic cluster headache (CH) as well. Our aims were to compare the concentrations of compounds both in headache-free and attack periods, and to find correlations between Trp metabolism and the clinical features of CH. Levels of 11 molecules were determined in peripheral blood plasma of healthy controls (n = 22) and interbout/ictal periods of CH patients (n = 24) by neurochemical measurements. FINDINGS: Significantly decreased L-kynurenine (KYN, p < 0.01), while increased quinolinic acid (QUINA, p < 0.005) plasma concentrations were detected in the interbout period of CH patients compared to healthy subjects. The levels of KYN are further reduced during the ictal period compared to the controls (p < 0.006). There was a moderate, negative correlation between disease duration and interbout QUINA levels (p < 0.048, R = - 0.459); and between the total number of CH attacks experienced during the lifetime of patients and the interbout KYN concentrations (p < 0.024, R = - 0.516). Linear regression models revealed negative associations between age and levels of Trp, kynurenic acid, 3-hdyroxyanthranilic acid and QUINA in healthy control subjects, as well as between age and ictal level of anthranilic acid. CONCLUSIONS: Our results refer to a specifically altered Trp metabolism in CH patients. The onset of metabolic imbalance can be attributed to the interbout period, where the decreased KYN level is unable to perform its protective functions, while the concentration of QUINA, as a toxic compound, increases. These processes can trigger CH attacks, which may be associated with glutamate excess induced neurotoxicity, neuroinflammation and oxidative stress. Further studies are needed to elucidate the exact functions of these molecular alterations that can contribute to identify new, potential biomarkers in the therapy of CH.

Chronic Migraine as a Primary Chronic Pain Syndrome and Recommended Prophylactic Therapeutic Options: A Literature Review.

Chronic pain conditions have a high socio-economic impact and represent a burden for patients, and their management is a challenge for healthcare professionals. Chronic migraine is one of the chronic primary headache disorders, which belong to chronic primary pain syndromes as per the new concept of multiple parenting. The aims of this review were to provide an overview of the latest classification systems involving both entities, the epidemiological data, and the currently recommended prophylactic treatment options for chronic migraine. Randomized controlled clinical trials, meta-analyses, real-world data, and review articles were analyzed. Chronic migraine is a prevalent and highly burdensome disease and is associated with high headache-related disability and worsening health-related quality of life. Treatment of chronic migraine includes pharmacological or, in drug-refractory cases, non-pharmacological (e.g., neuromodulatory) approaches. Among pharmacological treatment options, injectable botulinum toxin type A and calcitonin gene-related peptide-targeting human and fully humanized monoclonal antibodies (i.e., eptinezumab, erenumab, fremanezumab, and galcanezumab) are highly recommended in the preventive treatment of chronic migraine. Novel migraine-specific therapies offer a solution for this devastating and difficult-to-treat chronic pain condition.

Exploring Novel Therapeutic Targets in the Common Pathogenic Factors in Migraine and Neuropathic Pain.

Migraine and neuropathic pain (NP) are both painful, disabling, chronic conditions which exhibit some symptom similarities and are thus considered to share a common etiology. The calcitonin gene-related peptide (CGRP) has gained credit as a target for migraine management; nevertheless, the efficacy and the applicability of CGRP modifiers warrant the search for more effective therapeutic targets for pain management. This scoping review focuses on human studies of common pathogenic factors in migraine and NP, with reference to available preclinical evidence to explore potential novel therapeutic targets. CGRP inhibitors and monoclonal antibodies alleviate inflammation in the meninges; targeting transient receptor potential (TRP) ion channels may help prevent the release of nociceptive substances, and modifying the endocannabinoid system may open a path toward discovery of novel analgesics. There may exist a potential target in the tryptophan-kynurenine (KYN) metabolic system, which is closely linked to glutamate-induced hyperexcitability; alleviating neuroinflammation may complement a pain-relieving armamentarium, and modifying microglial excitation, which is observed in both conditions, may be a possible approach. Those are several potential analgesic targets which deserve to be explored in search of novel analgesics; however, much evidence remains missing. This review highlights the need for more studies on CGRP modifiers for subtypes, the discovery of TRP and endocannabinoid modulators, knowledge of the status of KYN metabolites, the consensus on cytokines and sampling, and biomarkers for microglial function, in search of innovative pain management methods for migraine and NP.

[COVID-19 and chronic pain: online survey in the domestic population]. / Covid-19 és krónikus fájdalom: online felmérés a pandémia alatt fájdalommal élo, ellátásban nem részesülo személyek körében.

Background and purpose: The problems caused by the COVID-19 epidemic have the worst impact on chronic patient populations. People with chronic pain are one of the most vulnerable groups due to stress, disruption of daily routine, family problems, illness and difficulty in hospital care. It is therefore essential to assess the situation and mental well-being of this group. The aim of this survey was to assess chronic pain patients during the COVID-19 pandemic, addressing psychological background factors that might affect pain symptoms, such as depression, emotion regulation, alexithymia, well-being, health literacy and social support. Methods: 158 people participated in the survey, reporting pain for at least 3 months but had not received medical treatment. Data was collected at two dates: February and December 2021. Participants completed an online questionnaire due to the pandemic situation. The following six psychological questionnaires were used in the survey: Toronto Alexithymia Scale, Beck Depression Inventory 9-item version, Difficulty in Emotion Regulation Scale, Multidimensional Scale of Perceived Social Support, Chew-questions measuring health literacy, WHO Well-being Index. Results: The participants ranged from 20 to 80 years in age, of whom 140 (88%) were female. 42 participants (27%) achieved severe alexithymia. 118 people (75%) had depression, of which 72 people (46%) had mild depression, 26 (16%) had moderate depression, and 20 (13%) had severe depression. The degree of pain and alexithy-mia (r(158) = 0.16, p = 0.004), depression (r(158) = 0.41, p < 0.001), difficulties in emotion regulation (r(158) = 0.26, p = 0.004), and health literacy, and difficulties in emotion regulation (r(158) = 0.25, p = 0.001) were positively and significantly related. Conclusion: In addition to the characteristic comorbidities of people living with pain (e.g. anxiety, emotion disorder, sleep disorder), the epidemic-induced prolonged social isolation, stress and fear of illness may explain the proportion of high depression, emotion regulation difficulties or health literacy problems in the study sample which exacerbate alexithymia and the degree of pain. Based on these results it is important to draw the attention of professionals to the appropriate health care and educational needs of those affected.

Trends in opioid utilization in Hungary, 2006-2020: A nationwide retrospective study with multiple metrics.

BACKGROUND: Opioid use is well documented in several countries: some countries struggle with overuse, whereas others have almost no access to opioids. For Europe, limited data are available. This study analysed Hungarian opioid utilization in ambulatory care between 2006 and 2020. METHODS: We obtained national drug utilization data on reimbursed opioid analgesics (ATC code: N02A) from a national health insurance database for a 15-year period. We investigated utilization trends, using three volume-based metrics [defined daily dose per 1000 inhabitants per day (DID), oral morphine equivalent per 1000 inhabitants per day, packages dispensed per 1000 inhabitants per year]. We stratified data based on administration routes, analgesic potency and reimbursement categories. RESULTS: Total opioid utilization increased during the study period according to all three metrics (74% in DID) and reached 5.31 DID by 2020. Upward trends were driven by an increase both in weak and strong opioid use (79% vs. 53%). The most commonly used opioids were fentanyl (in the strong category; 0.76 DID in 2020) and tramadol (in the weak category; 2.62 DID in 2020). Overall, tramadol was also the most commonly used opioid throughout the study period. Oral administration of opioid medications was dominant. Based on reimbursement categories, musculoskeletal pain was becoming a more frequent indication for opioid use (1552% increase in DID), while opioid use for cancer pain declined significantly during the study period (-33% in DID). CONCLUSIONS: Our low utilization numbers might indicate underuse of opioid analgesia, especially for cancer pain. SIGNIFICANCE: This study was one of the recent opioid utilization studies using three volume-based metrics, covering a long time period. To our knowledge, this was also the first national, population level study describing opioid utilization in Hungary. National opioid utilization data suggested not an overuse but rather an underuse of opioid analgesics in a developed, Central European country.

CGRP and CGRP-Receptor as Targets of Migraine Therapy: Brain Prize-2021.

BACKGROUND: Migraine is a highly prevalent primary headache with an unclear pathomechanism. During the last 40 years, numerous hypotheses have arisen; among them, the theory of the trigeminovascular system is the primary one. It serves as a skeleton in successful preclinical studies and in the development of effective therapeutic options for migraine headache. OBJECTIVE: The brain prize (awarded annually by the Lundbeck Foundation) is the most prestigious tribute in neuroscience. The winners in 2021 were Lars Edvinsson, Peter Goadsby, Michael Moskowitz and Jes Olesen. They are the fathers of migraine pathomechanism, which led to revolutionary new treatments. This review summarizes their landmark findings. METHODS: Data related to this topic were reviewed from PubMed records published between 1979 and May 2021. Searches were based on preclinical and clinical studies in the covered field. The findings were listed in chronological order. From a therapeutic perspective, only randomized controlled trials and meta-analysis were discussed. RESULTS: The calcitonin gene-related peptide-related pathogenesis of migraine is based on the activation of the trigeminovascular system. The therapeutic triad for migraine is triptans, gepants, and calcitonin gene-related peptide-targeted monoclonal antibodies. CONCLUSION: In the past 40 years, the systematic work of leading headache scientists has resulted in robust theoretical and therapeutic knowledge in the preclinical and clinical study of migraine.

A clinical study of an online educational programme for chronic pain patients.

BACKGROUND AND PURPOSE: Background - The research of alexithymia - the inability to express or understand emotions - has recently become of great importance in clinical practice, mainly in the field of doctor-patient and psychologist patient communication. Many studies have proven the correlation between alexithymia and the development of functional somatic symptoms, i.e. somatization. Purpose - The aim of this clinical study was to examine the emotion-recognition and emotion communication patterns of patients suffering from chronic pain (e.g., headache, low back pain, arthralgia, neuropathy). Moreover, the participants received access to the Hungarian adaptation of a new international online educational site (www.retrainpain.org) dealing with pain management. METHODS: Data were collected from the Headache and Chronic Pain Outpatient Clinic, Department of Neurology, Faculty of Medicine, University of Szeged, Hungary (tertiary care - Group 1) and from a general practice in district 2, Budapest, Hungary (primary care - Group 2) from March, 2017 to April, 2018. Patients received a test package containing a pain-specific questionnaire, then the Difficulties in Emotion Regulation Scale (DERS), the Toronto Alexithymia Scale (TAS-20), and the shortened Hungarian version of the WHO-Well-being (WBI-5) had to be completed. After filling out the questionnaires, all patients got access to the Hungarian adaptation of the www.retrainpain.org website. RESULTS: Altogether 92 patients participated in the study (Group 1 n=50; Group 2 n=42). Based on the TAS-20 re-sults, 35 patients reached a pathological score (≥60 points), which indicates the diagnosis of alexithymia. The mean TAS-score was lower in Group 2 (primary care) than in Group 1 (tertiary care) (p=0.003). The DERS disclosed pathological results in 19 cases (p=0.009). As regards the www.retrainpain.org chapters, we received feedback only from 25 out of 92 patients (27%) (Group 1 n=20; Group 2 n=5). CONCLUSION: Although the examined patients have been suffering from different chronic pain syndromes for years and 50% of them confirmed that symptoms placed at least moderate or heavy burden on their everyday life, the available educational programme was studied only by a smaller proportion of patients than expected. Additionally, those who surveyed the Hungarian adaptation of the www.retrainpain.org website were mainly patients from primary care (Group 2), in spite of the fact that patients from specialized medical care (Group 1) had worse subjective conditions. Our future objective is to extend our database with follow-up results and to improve patients' response willingness.

Therapeutic Approaches for Peripheral and Central Neuropathic Pain.

Neuropathic pain is a chronic secondary pain condition, which is a consequence of peripheral or central nervous (somatosensory) system lesions or diseases. It is a devastating condition, which affects around 7% of the general population. Numerous etiological factors contribute to the development of chronic neuropathic pain. It can originate from the peripheral part of the nervous system such as in the case of trigeminal or postherpetic neuralgia, peripheral nerve injury, painful polyneuropathies, or radiculopathies. Central chronic neuropathic pain can develop as a result of spinal cord or brain injury, stroke, or multiple sclerosis. As first-line pharmacological treatment options, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids are recommended. In trigeminal neuralgia, carbamazepine and oxcarbazepine are the first-choice drugs. In drug-refractory cases, interventional, physical, and psychological therapies are available. This review was structured based on a PubMed search of papers published in the field from 2010 until May 2019.

Are Migraine With and Without Aura Really Different Entities?

Background: Migraine research is booming with the rapidly developing neuroimaging tools. Structural and functional alterations of the migrainous brain were detected with MRI. The outcome of a research study largely depends on the working hypothesis, on the chosen measurement approach and also on the subject selection. Against all evidence from the literature that migraine subtypes are different, most of the studies handle migraine with and without aura as one disease. Methods: Publications from PubMed database were searched for terms of "migraine with aura," "migraine without aura," "interictal," "MRI," "diffusion weighted MRI," "functional MRI," "compared to," "atrophy" alone and in combination. Conclusion: Only a few imaging studies compared the two subforms of the disease, migraine with aura, and without aura, directly. Functional imaging investigations largely agree that there is an increased activity/activation of the brain in migraine with aura as compared to migraine without aura. We propose that this might be the signature of cortical hyperexcitability. However, structural investigations are not equivocal. We propose that variable contribution of parallel, competing mechanisms of maladaptive plasticity and neurodegeneration might be the reason behind the variable results.

Altered Resting State Functional Activity and Microstructure of the White Matter in Migraine With Aura.

Introduction: Brain structure and function were reported to be altered in migraine. Importantly our earlier results showed that white matter diffusion abnormalities and resting state functional activity were affected differently in the two subtypes of the disease, migraine with and without aura. Resting fluctuation of the BOLD signal in the white matter was reported recently. The question arising whether the white matter activity, that is strongly coupled with gray matter activity is also perturbed differentially in the two subtypes of the disease and if so, is it related to the microstructural alterations of the white matter. Methods: Resting state fMRI, 60 directional DTI images and high-resolution T1 images were obtained from 51 migraine patients and 32 healthy volunteers. The images were pre-processed and the white matter was extracted. Independent component analysis was performed to obtain white matter functional networks. The differential expression of the white matter functional networks in the two subtypes of the disease was investigated with dual-regression approach. The Fourier spectrum of the resting fMRI fluctuations were compared between groups. Voxel-wise correlation was calculated between the resting state functional activity fluctuations and white matter microstructural measures. Results: Three white matter networks were identified that were expressed differently in migraine with and without aura. Migraineurs with aura showed increased functional connectivity and amplitude of BOLD fluctuation. Fractional anisotropy and radial diffusivity showed strong correlation with the expression of the frontal white matter network in patients with aura. Discussion: Our study is the first to describe changes in white matter resting state functional activity in migraine with aura, showing correlation with the underlying microstructure. Functional and structural differences between disease subtypes suggest at least partially different pathomechanism, which may necessitate handling of these subtypes as separate entities in further studies.

Therapeutic strategies that act on the peripheral nervous system in primary headache disorders.

Introduction: Acute and preventive treatment of primary headache disorders is not completely resolved with regard to efficacy, safety, and tolerability. Hence, peripheral and central neuromodulation can provide therapeutic alternatives in drug-resistant cases. Peripheral targets of neuromodulation include invasive and non-invasive neurostimulation and electrical and chemical nerve and ganglion blockades. Areas covered: A PubMed search of papers published from January 2012 to October 2018 was conducted. The goal of this review was to analyze the efficacy and safety of invasive (implantable) peripheral neurostimulation methods (the occipital nerve, the cervical branch of vagal nerve, the sphenopalatine ganglion) and non-invasive (transcutaneous) peripheral neurostimulation methods (the occipital nerve, the supraorbital nerve, and the cervical and auricular branches of the vagal nerve), based on the results of published clinical trials and case series. Acting also on the peripheral nervous system, peripheral nerve (i.e. greater occipital nerve) and ganglion (i.e. sphenopalatine ganglion) blockades, botulinum neurotoxin type A-hemagglutinin complex therapies, and calcitonin gene-related peptide-related monoclonal antibody treatments in this patient population are also discussed. Expert opinion: This review summarizes the latest results on the therapeutic strategies acting on the periphery in primary headache disorders. These therapeutic options are minimally invasive or non-invasive, efficacious, safe, and well tolerated.

Treating status migrainosus in the emergency setting: what is the best strategy?

INTRODUCTION: Migraine is a disabling primary headache disorder with unknown exact pathomechanism. Status migrainosus (SM) is a complication of migraine (with or without aura), representing an attack that lasts for more than 72 h. There is a paucity of data published with regard to its pathomechanism and therapeutic options. AREAS COVERED: The authors review the literature on SM from PubMed published between 1999 and January 2018. The authors specifically look at the therapeutic possibilities of SM in the emergency department in patients that have or have not already been treated with serotonergic agents. Additional discussion is given to the rare complications of migraine. EXPERT OPINION: SM is a devastating condition; therefore, the primary goal is to prevent its development with proper acute and prophylactic migraine medication. If this treatment fails, the patient should be treated in the emergency setting. Due to the severity of the condition, parenteral pharmacotherapy is recommended. However, high-quality randomized trials are lacking. The currently available data suggest the use of intravenous fluids, corticosteroids, magnesium sulfate, anticonvulsive drugs, nonsteroidal anti-inflammatory drugs, antiemetics, and serotonergic agents for the treatment of SM. Still, there is a need for personalized and causal therapy for migraine sufferers.

Macro- and microstructural alterations of the subcortical structures in episodic cluster headache.

Background Previous functional and structural imaging studies have revealed that subcortical structures play a key a role in pain processing. The recurring painful episodes might trigger maladaptive plasticity or alternatively degenerative processes that might be detected by MRI as changes in size or microstructure. In the current investigation, we aimed to identify the macro- and microstructural alterations of the subcortical structures in episodic cluster headache. Methods High-resolution T1-weighted and diffusion-weighted MRI images with 60 gradient directions were acquired from 22 patients with cluster headache and 94 healthy controls. Surface-based segmentation analysis was used to measure the volume of the subcortical nuclei, and mean diffusion parameters (fractional anisotropy, mean, radial and axial diffusivity) were determined for these structures. In order to understand whether the size and diffusion parameters could be investigated in a headache lateralised manner, first the asymmetry of the size and diffusion parameters of the subcortical structures was analysed. Volumes and diffusion parameters were compared between groups and correlated with the cumulative number of headache days. To account for the different size of the patient and control group, a bootstrap approach was used to investigate the stability of the findings. Results A significant lateralisation of the size (caudate, putamen and thalamus) and the diffusion parameters of the subcortical structures were found in normal controls. In cluster headache patients, the mean fractional anisotropy of the right amygdalae, the mean axial and mean diffusivity of the right caudate nucleus and the radial diffusivity of the right pallidum were higher. The mean anisotropy of the right pallidum was lower in patients. Conclusion The analysis of the pathology in the subcortical structures in episodic cluster headache reveals important features of the disease, which might allow a deeper insight into the pathomechanism of the pain processing in this headache condition.

Kynurenines and PACAP in Migraine: Medicinal Chemistry and Pathogenetic Aspects.

BACKGROUND: Migraine is a highly disabling neurovascular primary headache disorder, with its exact pathomechanism being still unrevealed. The current leading hypotheses are based on the sensitization and activation of the trigeminovascular system. OBJECTIVE: To review the literature with focus on the effects of kynurenines (L-kynurenine and kynurenic acid) and pituitary adenylate cyclase-activating polypeptide on the regulation of the trigeminovascular system. METHOD: A literature search was conducted to identify preclinical and clinical publications (198 references) by using the keywords 'kynurenines', 'pituitary adenylate cyclase-activating polypeptide', and 'migraine' in the database of MEDLINE/PubMed up to 10 September 2016 for topical review. Additional filters used included 'review', 'systematic review', 'original article', and 'English language'. RESULTS: L-kynurenine and kynurenic acid act on the glutamatergic system at the level of the second-order nociceptive neurons in the trigeminal nucleus caudalis. Pituitary adenylate cyclase- activating polypeptide is released from the peripheral nerve endings of the trigeminal pseudounipolar neurons and causes vasodilation and mast cell degranulation, leading to consequent peripheral sensitization of the dural nociceptors. Centrally released pituitary adenylate cyclase-activating polypeptide in the trigeminal nucleus caudalis results in the central sensitization of the second-order neurons. The sensitization process leads to the characteristic features of migraine. CONCLUSION: L-kynurenine, kynurenic acid, and pituitary adenylate cyclase-activating polypeptide may have fundamental roles in the initiation of migraine headache attacks.