Sensory nerves in man and their role in primary headaches

What is the evidence for the use of corticosteroids in migraine?

Corticosteroids are widely prescribed for the management of migraine attacks. The earliest clinical studies examining the efficacy of corticosteroid monotherapy for managing migraine attacks date back to 1952. Since then, 26 heterogeneous clinical studies and four meta-analyses have been conducted to assess the efficacy of corticosteroids in either aborting acute migraine attacks, prolonged migraine attacks or recurrent headaches. Most of these (86 %) studies employed different comparator arms with corticosteroids monotherapy administration while some studies (14 %) evaluated adjunctive corticosteroid therapy. The majority of these clinical studies revealed the superior efficacy of corticosteroids as mono- or adjunctive-therapy both for recurrent and acute migraine attacks, while the remaining showed non-inferior efficacy. Different forms of oral and parenteral corticosteroids in either single-dose or short-tapering schedules are prescribed; there are clinical studies supporting the efficacy of both methods. Corticosteroids can be administered safely up to six times annually. Corticosteroids are also useful in managing patients who frequent emergency departments with "medication-seeking behavior." Migraine patients with refractory headaches, history of recurrent headaches, severe baseline disability, and status migrainosus were found to have the most beneficial response from corticosteroid therapy.

Two TRPV1 receptor antagonists are effective in two different experimental models of migraine

Background

The capsaicin and heat responsive ion channel TRPV1 is expressed on trigeminal nociceptive neurons and has been implicated in the pathophysiology of migraine attacks. Here we investigate the efficacy of two TRPV1 channel antagonists in blocking trigeminal activation using two in vivo models of migraine.

Methods

Male Sprague–Dawley rats were used to study the effects of the TRPV1 antagonists JNJ-38893777 and JNJ-17203212 on trigeminal activation. Expression of the immediate early gene c-fos was measured following intracisternal application of inflammatory soup. In a second model, CGRP release into the external jugular vein was determined following injection of capsaicin into the carotid artery.

Results

Inflammatory up-regulation of c-fos in the trigeminal brain stem complex was dose-dependently and significantly reduced by both TRPV1 antagonists. Capsaicin-induced CGRP release was attenuated by JNJ-38893777 only in higher dosage. JNJ-17203212 was effective in all doses and fully abolished CGRP release in a time and dose-dependent manner.

Conclusion

Our results describe two TRPV1 antagonists that are effective in two in vivo models of migraine. These results suggest that TRPV1 may play a role in the pathophysiological mechanisms, which are relevant to migraine.

Pathophysiology of autism spectrum disorders: Revisiting gastrointestinal involvement and immune imbalance

Autism spectrum disorders (ASD) comprise a group of neurodevelopmental abnormalities that begin in early childhood and are characterized by impairment of social communication and behavioral problems including restricted interests and repetitive behaviors. Several genes have been implicated in the pathogenesis of ASD, most of them are involved in neuronal synaptogenesis. A number of environmental factors and associated conditions such as gastrointestinal (GI) abnormalities and immune imbalance have been linked to the pathophysiology of ASD. According to the March 2012 report released by United States Centers for Disease Control and Prevention, the prevalence of ASD has sharply increased during the recent years and one out of 88 children suffers now from ASD symptoms. Although there is a strong genetic base for the disease, several associated factors could have a direct link to the pathogenesis of ASD or act as modifiers of the genes thus aggravating the initial problem. Many children suffering from ASD have GI problems such as abdominal pain, chronic diarrhea, constipation, vomiting, gastroesophageal reflux, and intestinal infections. A number of studies focusing on the intestinal mucosa, its permeability, abnormal gut development, leaky gut, and other GI problem raised many questions but studies were somehow inconclusive and an expert panel of American Academy of Pediatrics has strongly recommended further investigation in these areas. GI tract has a direct connection with the immune system and an imbalanced immune response is usually seen in ASD children. Maternal infection or autoimmune diseases have been suspected. Activation of the immune system during early development may have deleterious effect on various organs including the nervous system. In this review we revisited briefly the GI and immune system abnormalities and neuropeptide imbalance and their role in the pathophysiology of ASD and discussed some future research directions.

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the circulation after sumatriptan

Background and purpose The origin of migraine pain is still elusive, but increasingly researchers focus on the neuropeptides in the perivascular space of cranial vessels as important mediators of nociceptive input during migraine attacks. The parasympathetic neurotransmitters, pituitary adenylate cyclase activating peptide-38 (PACAP38) and vasoactive intestinal peptide (VIP) may be released from parasympathetic fibres and activate sensory nerve fibres during migraine attacks. Triptans are effective and well tolerated in acute migraine management but the exact mechanism of action is still debated. Triptans might reduce circulating neuropeptides. To examine this question, we examined the effect of sumatriptan on VIP and PACAP levels in vivo, under conditions without trigeminovascular system activation. Methods In 16 healthy volunteers we measured VIP and PACAP levels before and after administration of subcutaneous sumatriptan. We simultaneously collected blood samples from the internal and external jugular, the cubital veins and the radial artery, thereby covering both the cerebral and systemic circulation. VIP and PACAP determinations were assayed blindly with respect to timing and vascular compartments, but with all samples of a patient in the same assay, to minimize the influence of interassay variation. Results We found no difference in VIP and PACAP concentrations between the internal and external jugular, the cubital veins and the radial artery, (P>0.05), and the circulating levels of VIP and PACAP did not change over time (P>0.05). We found excellent agreement between neuropeptide levels in the internal and the external jugular system. Conclusion Sumatriptan did not change the levels of circulating VIP and PACAP in the intra or extra cerebral circulation in healthy volunteers. Under baseline conditions, without trigeminovascular activation, sumatriptan does not affect the release of neuropeptides VIP and PACAP. Implications Our results indicate no effect of 5-HT1B/D receptor activation on circulating levels of VIP and PACAP in humans without trigeminovascular activation. Given that neuropeptides play an important role for migraine it would be interesting to conduct a similar study in a migraine population.

Discovery of (R)-N-(3-(7-methyl-1H-indazol-5-yl)-1-(4-(1-methylpiperidin-4-yl)-1-oxopropan-2-yl)-4-(2-oxo-1,2-dihydroquinolin-3-yl)piperidine-1-carboxamide (BMS-742413): a potent human CGRP antagonist with superior safety profile for the treatment of migraine through intranasal delivery

Calcitonin gene-related peptide (CGRP) receptor antagonists have been shown to be efficacious as abortive migraine therapeutics with the absence of cardiovascular liabilities that are associated with triptans. Herein, we report the discovery of a highly potent CGRP receptor antagonist, BMS-742413, with the potential to provide rapid onset of action through intranasal delivery. The compound displays excellent aqueous solubility, oxidative stability, and toxicological profile. BMS-742413 has good intranasal bioavailability in the rabbit and shows a robust, dose-dependent inhibition of CGRP-induced increases in marmoset facial blood flow.

What makes a CGRP2 receptor?

1. Heterogeneity in the receptors for the neuropeptide calcitonin gene-related peptide (CGRP) has been apparent for nearly 20 years. This is most clearly manifested in the observation of CGRP(8-37)-sensitive and -insensitive populations of CGRP-activated receptors. The pA(2) values for CGRP(8-37) in excess of 7 are widely considered to be the result of antagonism of CGRP(1) receptors, whereas those below 7 are believed to be the consequence of antagonism of a second population of receptors, namely CGRP(2) receptors. 2. However, a multitude of pA(2) values exist for CGRP(8-37), spanning several log units, and as such no obvious clusters of values are apparent. Understanding the molecular nature of the receptors that underlie this phenomenon is likely to aid the development of selective pharmacological tools to progress our understanding of the physiology of CGRP and related peptides. Because there is active development of CGRP agonists and antagonists as therapeutics, such information would also further this pursuit. 3. The CGRP(1) receptor is pharmacologically and molecularly well defined as a heterodimer of the calcitonin receptor-like receptor (CL) and receptor activity modifying protein (RAMP) 1. The CL/RAMP1 complex is highly sensitive to CGRP(8-37). Conversely, the constituents of the CGRP(2) receptor have not been identified. In fact, there is little evidence for a distinct molecular entity that represents the CGRP(2) receptor. 4. Recent pharmacological characterization of receptors related to CGRP(1) has revealed that some of these receptors may explain CGRP(2) receptor pharmacology. Specifically, AMY(1(a)) (calcitonin receptor/RAMP1) and AM(2) (CL/RAMP3) receptors can be activated by CGRP but are relatively insensitive to CGRP(8-37). 5. This, along with other supporting data, suggests that the 'CGRP(2) receptor' that has been extensively reported in the literature may, in fact, be an amalgamation of contributions from a variety of CGRP-activated receptors. The use of appropriate combinations of agonists and antagonists, along with receptor expression studies, could allow such receptors to be separated.

Efficacy of sumatriptan tablets in migraineurs self-described or physician-diagnosed as having sinus headache: a randomized, double-blind, placebo-controlled study

BACKGROUND

Many patients and physicians interpret episodic headache in the presence or absence of nasal symptoms as "sinus' headache, while ignoring the possible diagnosis of migraine.

OBJECTIVE

The purpose of this study was to assess the efficacy and tolerability of sumatriptan succinate 50-mg tablets in patients with migraine presenting with "sinus" headache.

METHODS

A randomized, double-blind, placebo-controlled, multicenter study was conducted in adult (aged 18-65 years) migraine patients presenting with self-described or physician-diagnosed "sinus" headache. From November 2001 to March 2002, patients meeting International Headache Society criteria for migraine (with > or =2 of the following: unilateral location, pulsating quality, moderate or severe intensity, aggravation by moderate physical activity; and > or =1 of: phonophobia and phonophobia, nausea and/or vomiting) and with no evidence of bacterial rhinosinusitis were enrolled and randomized in a 1:1 ratio via computer-generated randomization schedule to receive either 1 sumatriptan 50-mg tablet or matching placebo tablet. The primary efficacy end point was headache response (moderate or severe headache pain reduced to mild or no headache pain) at 2 hours after administration. The presence or absence of migraine-associated symptoms and sinus and nasal symptoms was also measured. Tolerability was assessed through patient-reported adverse events (AEs).

RESULTS

Two hundred sixteen patients with self-described or physician-diagnosed "sinus" headache received a migraine diagnosis and treated 1 migraine attack with sumatriptan 50 mg. The efficacy (intent-to-treat) analysis included 215 patients treated with sumatriptan 50 mg (n = 108; mean [SD] age, 39.6 [12.3] years; mean [SD] weight, 77.7 [17.7] kg; sex, 71% female; race, 69% white) or placebo (n = 107; mean [SD] age, 41.0 [11.3] years; mean [SD] weight 80.7 [20.9] kg; sex, 69% female; race, 64% white). Significantly more patients treated with sumatriptan 50 mg achieved a positive headache response at 2 and 4 hours after administration compared with those treated with placebo (69% vs 43% at 2 hours and 76% vs 49% at 4 hours, respectively; both, P < 0.001). Significantly more sumatriptan-treated patients were free from sinus pain compared with placebo recipients at 2 hours (63% vs 49% placebo, P = 0.049) and 4 hours (77% vs 55%, P = 0.001). All treatments were generally well tolerated. The most common drug-related AEs reported in the sumatriptan and placebo groups, respectively, were dizziness (5% vs < 1%), nausea (3% vs 2%), other pressure/tightness (defined as sense of heaviness; heaviness of upper body, upper extremities; jaw tension; neck tension) (4% vs 0%), and temperature sensations (defined as warm feeling of back of neck, or flushing) (2% vs 0%). No patients experienced any serious AEs.

CONCLUSIONS

Sumatriptan 50-mg tablets were effective and generally well tolerated in the treatment of these patients presenting with migraine headaches that were self-described or physician-diagnosed as sinus headaches.

Non-peptide calcitonin gene-related peptide receptor antagonists from a benzodiazepinone lead

High-throughput screening of the Merck sample collection identified benzodiazepinone tetralin-spirohydantoin 1 as a CGRP receptor antagonist with micromolar activity. Comparing the structure of 1 with those of earlier peptide-based antagonists such as BIBN 4096 BS, a key hydrogen bond donor-acceptor pharmacophore was hypothesized. Subsequent structure activity studies supported this hypothesis and led to benzodiazepinone piperidinyldihydroquinazolinone 7, CGRP receptor K(i)=44nM and IC(50)=38nM. Compound 7 was orally bioavailabile in rats and is a lead in the development of orally bioavailable CGRP antagonists for the treatment of migraine.

Raeder's syndrome after embolization of a giant intracavernous carotid artery aneurysm: pathophysiological considerations

We present the case of a 47 years old woman submitted to an endovascular trapping of a left cavernous internal carotid artery aneurysm, in which the distal balloon was inflated, as usually done, within the cavernous segment of the internal carotid artery, different from the proximal one which was inflated inside the carotid canal due to technical problems. Consequently, a clinical picture of Raeder's paratrigeminal neuralgia took place. This is the first case report in the literature with theses characteristics. A review of the anatomic pathways and further considerations about the possible pathophysiological mechanisms involved are presented.

Long-term relief of posttraumatic headache by sphenopalatine ganglion pulsed radiofrequency lesioning: a case report11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors(s) or upon any organization with which the author(s) is/are associated

Posttraumatic headache is a common and disabling pain syndrome in patients who sustain a head injury. Unfortunately, conventional treatments may fail or cause intolerable side effects. Because chronic headache may be mediated by central and peripheral neural processes, these structures may be therapeutic targets. One target, the sphenopalatine ganglion (SPG), is implicated in several headache disorders and has been lesioned for headache relief. Because of the risks of neurolytic procedures, nonablative procedures that provide pain relief would be useful. We present a case wherein a man in his late twenties with posttraumatic headache obtained more than 17 months of relief with SPG pulsed-mode radiofrequency lesioning. SPG pulsed-mode radiofrequency is a nonablative, neural lesioning method that may be useful in the treatment of posttraumatic headache.

The ORL-1 (NOP1) receptor ligand nociceptin/orphanin FQ (N/OFQ) inhibits neurogenic dural vasodilatation in the rat

The effects of the ORL-1 (NOP(1)) receptor ligand nociceptin (N/OFQ) and the nociceptin antagonists [Nphe(1)]N/OFQ-(1-13)-NH(2) (Nphe) and nocistatin (NST) on neurogenic dural vasodilatation (NDV) in the rat dura mater evoked by electrical stimulation of a closed cranial window were studied. The middle meningeal artery was visualised using intravital microscopy, and the vessel diameter analysed using a video dimension analyser. N/OFQ (1, 10, 100 nmol kg(-1); i.v., n=10) significantly and dose-dependently suppressed NDV maximally by 65% (P<0.01). Neither Nphe (100 nmol kg(-1); n=5) nor NST (100 nmol kg(-1); n=4) alone had an effect on NDV (P>0.05). Baseline vessel diameter was not significantly affected by application of N/OFQ, NST or Nphe. Application of the selective N/OFQ antagonist Nphe (10, 100 nmol kg(-1) i.v., n=8) dose-dependently and significantly (P<0.01) reversed the inhibition of NDV induced by application of N/OFQ (10 nmol kg(-1)). NST (10, 100 nmol kg(-1); n=7) failed to reverse the effects elicited by N/OFQ. Application of N/OFQ elicited a dose-dependent transient decrease in arterial blood pressure (P<0.01). Nphe dose-dependently reversed the cardiovascular effects induced by application of N/OFQ (10 nmol kg(-1)) (P<0.01),while NST did not alter the blood pressure reaction elicited by N/OFQ. The results show that N/OFQ inhibits NDV, an effect which is antagonised by Nphe, but not by NST. ORL-1 (NOP(1)) receptors located on trigeminal sensory fibres may be involved in the regulation of dural vessel diameter and hence may play a role in migraine pathophysiology.