Sex hormones and headache

Progesterone receptor activation regulates sensory sensitivity

Women develop chronic pain during their reproductive years more often than men, and estrogen and progesterone regulate this susceptibility. We tested whether brain progesterone receptor (PR) signaling regulates pain susceptibility. During the estrous cycle, animals were more sensitive to pain during the estrus stage than in the diestrus stage, suggesting a role for reproductive hormones, estrogen, and progesterone. We measured the pain threshold daily for four days in ovariectomized, estrogen-primed animals treated with progesterone. The pain threshold was lower 2 days later and stayed that way for the duration of the testing. A specific progesterone-receptor (PR) agonist, segesterone, promoted pain, and mice lacking PR in the brain (PRKO) did not experience lowered pain threshold when treated with progesterone or segesterone. PR activation increased the cold sensitivity but did not affect the heat sensitivity and had a small effect on light sensitivity. Finally, we evaluated whether PR activation altered experimental migraine. Segesterone and nitroglycerin (NTG) when administered sequentially, reduced pain threshold but not separately. These studies have uncovered a pain-regulating function of PRs. Targeting PRs may provide a novel therapeutic avenue to treat chronic pain in women.

Complications of reversible cerebral vasoconstriction syndrome in relation to age

INTRODUCTION

Reversible cerebral vasoconstriction syndrome (RCVS) has a heterogenous clinical and radiological presentation. We investigated whether RCVS complications vary according to age.

PATIENTS AND METHODS

In a pooled French cohort of 345 patients with RCVS, we assessed (1) rates of clinical and radiological complications, and (2) the functional outcome at 3 months according to age as a continuous variable, and in young patients aged ≤ 49 years versus those aged ≥ 50 years. The Commission Nationale Informatique et Liberté and the local ethics committee approved this study (registration number: 202100733).

RESULTS

The risk for any focal deficit and for any brain lesion were independently associated with increasing age (OR 1.4, 95% CI 1.1-1.8; p = 0.014, and OR 1.6, 95% CI 1.2-2.1; p < 0.001, respectively). Subtypes of brain lesions independently associated with increasing age were subarachnoid haemorrhage (OR 1.7, 95% CI 1.3-2.3; p < 0.001) and intracerebral haemorrhage (OR 1.5, 95% CI 1.1-2.2; p = 0.023). Frequency of cervical artery dissections peaked at age 30-39, and young age was independently associated with cervical artery dissections (OR 13.6, 95% CI 2.4-76.6; p = 0.003). Age had no impact on the functional outcome, with a modified Rankin scale score of 0-1 in > 96% of patients.

CONCLUSION

Age seems to influence rates and types of complications of RCVS, with young age being associated with cervical artery dissections, and increasing age with haemorrhagic complications. If confirmed in larger prospective studies, recognition of age-specific patterns might help to guide clinical management and to identify complications in cases of RCVS and vice versa.

Prolactin and oxytocin: potential targets for migraine treatment

Migraine is a severe neurovascular disorder of which the pathophysiology is not yet fully understood. Besides the role of inflammatory mediators that interact with the trigeminovascular system, cyclic fluctuations in sex steroid hormones are involved in the sex dimorphism of migraine attacks. In addition, the pituitary-derived hormone prolactin and the hypothalamic neuropeptide oxytocin have been reported to play a modulating role in migraine and contribute to its sex-dependent differences. The current narrative review explores the relationship between these two hormones and the pathophysiology of migraine. We describe the physiological role of prolactin and oxytocin, its relationship to migraine and pain, and potential therapies targeting these hormones or their receptors.In summary, oxytocin and prolactin are involved in nociception in opposite ways. Both operate at peripheral and central levels, however, prolactin has a pronociceptive effect, while oxytocin appears to have an antinociceptive effect. Therefore, migraine treatment targeting prolactin should aim to block its effects using prolactin receptor antagonists or monoclonal antibodies specifically acting at migraine-pain related structures. This action should be local in order to avoid a decrease in prolactin levels throughout the body and associated adverse effects. In contrast, treatment targeting oxytocin should enhance its signalling and antinociceptive effects, for example using intranasal administration of oxytocin, or possibly other oxytocin receptor agonists. Interestingly, the prolactin receptor and oxytocin receptor are co-localized with estrogen receptors as well as calcitonin gene-related peptide and its receptor, providing a positive perspective on the possibilities for an adequate pharmacological treatment of these nociceptive pathways. Nevertheless, many questions remain to be answered. More particularly, there is insufficient data on the role of sex hormones in men and the correct dosing according to sex differences, hormonal changes and comorbidities. The above remains a major challenge for future development.

Menstrually-related stabbing headache in a patient without migraine: case report

Introduction Stabbing headache is considered a primary headache and is a prevalent entity in the general population.  Objective To present an unusual case of stabbing headache associated with menstruation. Method Data collected through complete anamnesis. Case report The authors report a case of a woman suffering from a stabbing headache which features that has not been previously described – a menstrual pattern in the presentation of stabbing headache attacks. Conclusions We conclude that this menstrual pattern of stabbing headache attacks is unusual in patients with primary stabbing headache and that it does not fulfil diagnostic criteria for migraine or tension-type headache.

New onset headache during delivery and postpartum: Clinical characteristics of a case series

Introduction

There are abundant studies on headache and migraine in women but few or none about their occurrence during labor, delivery, and postpartum (2 hours after delivery) owing to the low incidence. A headache attack can be debilitating when a woman is trying to manage labor pain. Research at our Women's Headache Center within the Department of Gynecology and Obstetrics has begun to shed light on this potential association.

Methods

For the present study 474 women with singleton pregnancy were enrolled. A headache questionnaire was administered at two time points. Headache history was investigated on admission to prenatal care at 36 weeks gestation. The women were followed by a midwife who monitored labor progression and recorded the onset and features of headache pain. During examination before hospital discharge at 3 days post-delivery, the headache questionnaire was reviewed by a headache specialist who differentiated headache type according to International Classification of Headache Disorders (3rd edition) criteria.

Results

Data analysis showed that 145/474 women had a history of headache: 65/145 (44.82%) reported a diagnosis of migraine. Eight reported experiencing a probable migraine attack (4 with aura) and one reported probable tension-type headache during labor or postpartum. All nine women who reported migraine/headache attack during labor had no previous history of headache or neurological illness. All had vaginal delivery. No onset of headache pain in patients with a previous history of headache was noted during delivery and postpartum.

Discussion

The onset of a headache attack during labor in women who usually do not experience headache suggests other pathogenic mechanisms underlying the attack and merits further study.

Wen Dan Tang: A Potential Jing Fang Decoction for Headache Disorders?

Background: Chinese herbal medicine is considered relatively safe, inexpensive, and easily accessible. Wen Dan Tang (WDT), a Jing Fang ancient classical Chinese herbal formula with a broad indication profile has been used for several centuries in China to treat various illnesses. Question: Are there evidence-based clinical trials that show that WDT has a significant impact on the treatment of various diseases, especially in patients with migraine and tension-type headaches (TTH)? Methods: This study is based on an online database search using PubMed, Medline, Cochrane Library, AcuTrials, Embase, Semantic Scholar, Jstor, internet research, and review of ancient and modern Chinese medical textbooks regarding WDT and its compounds. Results: There were no studies on WDT in migraine and TTH; therefore, this work gathers and describes data for every single compound in the formula. Conclusion: This study suggests that the bioactive compounds found in WDT composition show potential in treating patients with neurological, psychiatric disorders, cardiovascular diseases, metabolic syndrome, and digestive disorders. Some coherence between WDT in headache reduction and improvements in the quality of life in patients with migraines and TTH could be evaluated, showing positive results of WDT in these patients.

The applicability research of the diagnostic criteria for 6.7.2 angiography headache in the international classification of headache disorders-3rd edition

Background

Angiography headache (AH) is common but not negligible, and the criteria for AH have been based on only a few studies. The purpose of this study was to investigate the incidence, risk factors and possible mechanism of AH and reappraise the diagnostic criteria for AH in the International Classification of Headache Disorders 3 (ICHD-3).

Methods

Two hundred and seventy-nine patients completed this prospective, non-randomized study, including 107 patients who underwent cerebral angiography, 101 patients who underwent coronary intervention and 71 patients who underwent extremities arterial intervention. Patients were followed up with questionnaires immediately after the procedure and 24 h, 72 h, 1 week and 2 weeks after the procedure.

Results

The incidence of headache was 22.4% (24/107) in cerebral angiography group, 23.8% (24/101) in coronary intervention group, and 16.9% (12/71) in extremities arterial intervention group. Headache still occurred in 12.1% (13/107), 14.9% (15/101) and 11.3% (8/71) of patients 24 h after the procedure in the three groups, respectively. Two types of headache were observed in cerebral angiography group and coronary intervention group, one during and one after the procedure, while only postoperative headache was observed in extremities arterial intervention group. Previous headache history was a risk factor for headache in the three groups (p = 0.003 in cerebral angiography group, p = 0.006 in coronary intervention group, and p = 0.016 in extremities arterial intervention group). In addition, female (p = 0.008) was a risk factor for cerebral angiography group. Headache characteristics were described in detail.

Conclusions

The diagnostic criteria for 6.7.2 angiography headache in ICHD-3 may miss a number of cerebral AH with onset later than 24 h after the procedure. Therefore, it is recommended to revise it according to the literature and further studies. The incidence of headache was high during and after angiography and interventional procedure. It was suggested that the definition of headache due to coronary intervention and headache due to extremities arterial intervention should be added in ICHD.

The prevalence and burden of recurrent headache in Australian adolescents: findings from the longitudinal study of Australian children

Background

Headache disorders are highly prevalent worldwide, but not well investigated in adolescents. Few studies have included representative nationwide samples. This study aimed to present the prevalence and burden of recurrent headache in Australian adolescents.

Methods

The prevalence of recurrent headache, headache characteristics (severity and frequency) and burden on health-related quality of life in Australian children aged 10–17 years were presented, using nationally representative data from the Longitudinal Study of Australian children (LSAC). The LSAC, commencing in 2004, collects data every 2 years from a sample of Australian children of two different age cohorts: B ‘baby’ cohort, aged 0–1 years and K ‘kindergarten’ cohort, aged 4–5 years at the commencement of the study. Face-to-face interviews and self-complete questionnaires have been conducted with the study child and parents of the study child (carer-reported data) at each data collection wave, with seven waves of data available at the time of the current study. Wave 7 of the LSAC was conducted in 2016, with B cohort children aged 12–13 years and K cohort children aged 16–17 years. For the current study, data were accessed for four out of seven waves of available data (Wave 4–7) and presented cross-sectionally for the two cohorts of Australian children, for the included age groups (10–11 years, 12–13 years, 14–15 years and 16–17 years). All available carer-reported questionnaire data pertaining to headache prevalence, severity and frequency, general health and health-related quality of life, for the two cohorts, were included in the study, and presented for male and female adolescents. Carer-reported general health status of the study child and health-related quality of life scores, using the parent proxy-report of the Paediatric Quality of Life Inventory™ 4.0, were compared for male and female adolescents with recurrent headache and compared with a healthy group. Finally, health-related quality of life scores were compared based on headache frequency and severity.

Results

The LSAC study initially recruited 10,090 Australian children (B cohort n = 5107, K cohort n = 4983), and 64.1% of the initial sample responded at wave 7. Attrition rates across the included waves ranged from 26.3% to 33.8% (wave 6 and 7) for the B cohort, and 16.3% to 38.0% (wave 4–7) for the K cohort. Recurrent headache was more common in females, increasing from 6.6% in 10–11 years old females to 13.2% in 16–17 years old females. The prevalence of headache in males ranged from 4.3% to 6.4% across the age groups. Health-related quality of life scores were lower for all functional domains in adolescents with recurrent headache, for both sexes. Headache frequency, but not severity, was significantly associated with lower health-related quality of life scores, in both males and females.

Conclusions

Recurrent headache was common among Australian adolescents and increased in prevalence for females, across the age groups. Frequent recurrent headache is burdensome for both male and female adolescents. This study provides information regarding the prevalence and burden of recurrent headache in the adolescent population based on findings from the Longitudinal Study of Australian Children.

Adolescents' Explanatory Models for Headaches and Associations with Behavioral and Emotional Outcomes

More than one-third of adolescents experience recurrent headaches. Usually, these headaches are of primary origin and modulated by different biological and psychosocial factors. While parents are often consulted in scientific research and medical care about the nature of their child's headache, it is unclear to what extent parents and their children agree upon the factors that cause them. Adolescents' own attributions of headaches have rarely been investigated, and it is unclear how those attributions affect behavioral and emotional outcomes. In the present study, adolescents with chronic headaches (N = 248) and their parents (N = 120) rated the influence of various biological and psychosocial factors on the adolescents' headaches. Associations between these factors and several behavioral and emotional outcomes were examined. The most frequently reported factor by both samples was stress; however, concordance between parents and adolescents was generally low. The factor "other disease" was significantly associated with medication consumption and school absence. This study is one of the first to provide insights into adolescents' own attributions of headaches. Furthermore, the significant associations of the factor with behavioral outcomes reveal the importance of understanding personal explanatory models of headache. Future studies should examine associations between subjective headache causes and the individual's experience of the disorder to improve headache interventions.

Gender aspects of the pain syndrome

In recent years, the subject of sex differences in the pain experience attracts a growing interest. The epidemiological and clinical data indicate that women have increased risk of chronic pain, and according to some sources, even experience more intense pain. The hypothetical biological mechanisms underlying sex differences in pain perception consist in the modulating effects produced by sex hormones in relation to the neural substrate. This is confirmed by data on the distribution of gonadal hormones and their receptors in the areas of the peripheral and central nervous system that provide nociceptive transmission. The complexity of the estradiol and progesterone effects on pain sensitivity lies in the fact that, according to various data, both have pre-nociceptive and antinociceptive effects, and testosterone appears to be more characterized by antinociceptive properties. The lion’s share of researches demonstrates the effect of a clinical pain exacerbation during the menstrual cycle. There is irrefutable information about gender differences in responses to drug and non-drug pain treatment, although the results vary depending on a specific therapy and may depend on pain characteristics. Since the recommended dosage of a medication is often based on an “average” male weigh 70 kg, female patients may be facing the risk of increased therapeutic or adverse effects of a drug. The cause is in a higher average percentage of body fat, a lower mean body weight, which contributes to higher median drug concentrations compared with male patients. At present, the available evidence does not allow adapting the methods of pain syndrome treatment to a gender. However, such innovations are quite possible and desirable in the foreseeable future. Additional studies will be required to clarify the mechanisms that determine sex differences in pain responses in order to provide adequate pain relief, according to the patient’s needs.

Estrogen, migraine, and vascular risk

Migraine has a predilection for female sex and the course of symptoms is influenced by life stage (presence of menstrual cycle, pregnancy, puerperium, menopause) and use of hormone therapy, such as hormonal contraception and hormone replacement therapy. Hormonal changes figure among common migraine triggers, especially sudden estrogen drop. Moreover, estrogens can modulate neuronal excitability, through serotonin, norepinephrine, dopamine, and endorphin regulation, and they interact with the vascular endothelium of the brain. The risk of vascular disease, and ischemic stroke in particular, is increased in women with migraine with aura (MA), but the link is unclear. One hypothesis posits for a causal association: migraine may cause clinical or subclinical brain lesions following repeated episodes of cortical spreading depression (CSD) and a second hypothesis that may explain the association between migraine and vascular diseases is the presence of common risk factors and comorbidities. Estrogens can play a differential role depending on their action on healthy or damaged endothelium, their endogenous or exogenous origin, and the duration of their treatment. Moreover, platelet activity is increased in migraineurs women, and it is further stimulated by estrogens.This review article describes the course of migraine during various life stages, with a special focus on its hormonal pathogenesis and the associated risk of vascular diseases.

Treating migraine with contraceptives

At least 18% of women suffers from migraine. Clinically, there are two main forms of migraine: migraine with aura (MA) and migraine without aura (MO) and more than 50% of MO is strongly correlated to the menstrual cycle. The high prevalence of migraine in females, its correlation with the menstrual cycle and with the use of combined hormonal contraceptives (CHCs) suggest that the estrogen drop is implicated in the pathogenesis of the attacks. Although CHCs may trigger or worsen migraine, their correct use may even prevent or reduce some forms of migraine, like estrogen withdrawal headache. Evidence suggested that stable estrogen levels have a positive effect, minimising or eliminating the estrogenic drop. Several contraceptive strategies may act in this way: extended-cycle CHCs, CHCs with shortened hormone-free interval (HFI), progestogen-only contraceptives, CHCs containing new generation estrogens and estrogen supplementation during the HFI.

Menstrual migraine: a review of current and developing pharmacotherapies for women

INTRODUCTION

Migraine is one of the most common neurological disorders in the general population. It affects 18% of women and 6% of men. In more than 50% of women migraineurs the occurrence of migraine attacks correlates strongly with the perimenstrual period. Menstrual migraine is highly debilitating, less responsive to therapy, and attacks are longer than those not correlated with menses. Menstrual migraine requires accurate evaluation and targeted therapy, that we aim to recommend in this review.

AREAS COVERED

This review of the literature provides an overview of currently available pharmacological therapies (especially with triptans, anti-inflammatory drugs, hormonal strategies) and drugs in development (in particular those acting on calcitonin gene-related peptide) for the treatment of acute migraine attacks and the prophylaxis of menstrual migraine. The studies reviewed here were retrieved from the Medline database as of June 2017.

EXPERT OPINION

The treatment of menstrual migraine is highly complex. Accurate evaluation of its characteristics is prerequisite to selecting appropriate therapy. An integrated approach involving neurologists and gynecologists is essential for patient management and for continuous updating on new therapies under development.

Estrogen-Dependent Changes in Dura Mater Microvasculature Add New Insights to the Pathogenesis of Headache

The pathogenesis of headaches is a matter of ongoing discussion of two major theories describing it either as a vascular phenomenon resulting from vasodilation or primarily as a neurogenic process accompanied by secondary vasodilation associated with sterile neurogenic inflammation. While summarizing current views on neurogenic and vascular origins of headache, this mini review adds new insights regarding how smooth muscle-free microvascular networks, discovered within dura mater connective tissue stroma (previously thought to be “avascular”), may become a site of initial insult generating the background for the development of headache. Deficiencies in estrogen-dependent control of microvascular integrity leading to plasma protein extravasation, potential activation of perivascular and connective tissue stroma nociceptive neurons, and triggering of inflammatory responses are described. Finally, possible avenues for controlling and preventing these pathophysiological changes are discussed.

The effect of melatonin on gene expression of calcitonin gene-related peptide and some proinflammatory mediators in patients with pure menstrual migraine

The neuropeptide calcitonin gene-related peptide (CGRP), a potent vasoactive and a marker of trigeminal inflammation, has been considered as an important mediator in various types of migraine such as pure menstrual migraine. Earlier studies have shown that CGRP can modulate the synthesis and release of other inflammatory factor including nitric oxide (NO) and interleukin-1beta (IL-1β) from trigeminal ganglion glial cells. Exogenous melatonin protects the tissues from inflammatory damages. The goal of this study was to determine the anti-inflammatory effects of melatonin on the CGRP expression, inducible nitric oxide synthase (iNOS) activity, NO, and IL-1β release in cultured peripheral blood mononuclear cells (PBMCs) from pure menstrual migraine patients and healthy subjects. This study was performed on 12 pure menstrual migraine patients and 12 age-and sex-matched healthy subjects. PBMCs were isolated and treated with melatonin for 12 h at pharmacological dose. Gene expression was evaluated by real-time PCR. CGRP and IL-1β proteins in culture supernatant were determined by ELISA method. iNOS activity in PBMCs was determined by colorimetric assays. Total nitrite as an indicator of NO concentrations in the culture supernatants was measured using Griess method. We found that melatonin treatment significantly decreases mRNA expression of CGRP release, NO production, and iNOS activity in the patient groups. Taken together, it appears that melatonin reduces inflammation through decreasing CGRP level and iNOS activity in the patients with migraine; however, further studies are needed in this regard.

The Role of Adenosine Signaling in Headache: A Review

Migraine is the third most prevalent disease on the planet, yet our understanding of its mechanisms and pathophysiology is surprisingly incomplete. Recent studies have built upon decades of evidence that adenosine, a purine nucleoside that can act as a neuromodulator, is involved in pain transmission and sensitization. Clinical evidence and rodent studies have suggested that adenosine signaling also plays a critical role in migraine headache. This is further supported by the widespread use of caffeine, an adenosine receptor antagonist, in several headache treatments. In this review, we highlight evidence that supports the involvement of adenosine signaling in different forms of headache, headache triggers, and basic headache physiology. This evidence supports adenosine A_2A receptors as a critical adenosine receptor subtype involved in headache pain. Adenosine A_2A receptor signaling may contribute to headache via the modulation of intracellular Cyclic adenosine monophosphate (cAMP) production or 5' AMP-activated protein kinase (AMPK) activity in neurons and glia to affect glutamatergic synaptic transmission within the brainstem. This evidence supports the further study of adenosine signaling in headache and potentially illuminates it as a novel therapeutic target for migraine.

Hormone-Related Migraine Headaches and Mood Disorders: Treatment with Estrogen Stabilization

Because estrogens and the trigeminal system are inherently linked, prescribers who are treating a woman with a hormonally related mood disorder and migraine headaches should consider hormonal options to optimize the patient's treatment. This article discusses the interrelationships of estrogen, serotonin, and the trigeminal system as they relate to menstrual migraine occurrence and hormone-related mood symptoms. In addition, clinical examples are provided to facilitate the prescribers treating women during reproductive transitions in which declining estrogens are related to their suffering.

Rizatriptan for the Acute Treatment of ICHD-II Proposed Menstrual Migraine: Two Prospective, Randomized, Placebo-Controlled, Double-Blind Studies

These are the first prospective studies to use criteria for menstrual migraine proposed in the 2004 revision of the International Classification of Headache Disorders (ICHD-II) to examine the efficacy of rizatriptan for treatment of a menstrual attack. Two identical protocols (MM1 and MM2) were randomized, parallel, placebo-controlled, double-blind studies. Adult women with ICHD-II menstrual migraine were assigned to either rizatriptan 10-mg tablet or placebo in a 2 : 1 ratio. Patients treated a single menstrual migraine attack of moderate or severe pain intensity. The primary end-point was 2-h pain relief and the secondary end-point was 24-h sustained pain relief. A total of 707 patients (MM1 357, MM2 350) treated a menstrual migraine attack. The percentage of patients reporting 2-h pain relief was significantly greater for rizatriptan than for placebo (MM1 70% vs. 53%, MM2 73% vs. 50%), as was the percentage of patients reporting 24-h sustained pain relief (MM1 46% vs. 33%; MM2 46% vs. 33%). Rizatriptan 10 mg was effective for the treatment of ICHD-II menstrual migraine, as measured by 2-h pain relief and 24-h sustained pain relief.

Sex and Gender Differences in Central Nervous System-Related Disorders

There are important sex differences in the brain that seem to arise from biology as well as psychosocial influences. Sex differences in several aspects of human behavior and cognition have been reported. Gonadal sex steroids or genes found on sex chromosomes influence sex differences in neuroanatomy, neurochemistry and neuronal structure, and connectivity. There has been some resistance to accept that sex differences in the human brain exist and have biological relevance; however, a few years ago, it has been recommended by the USA National Institute of Mental Health to incorporate sex as a variable in experimental and clinical neurological and psychiatric studies. We here review the clinical literature on sex differences in pain and neurological and psychiatric diseases, with the aim to further stimulate interest in sexual dimorphisms in the brain and brain diseases, possibly encouraging more research in the field of the implications of sex differences for treating these conditions.

The use of progestogen-only pill in migraine patients

Migraine is a debilitating neurovascular disorder which is estimated to affect 18% of women and 6% of men. Two main forms of this neurological disorder must be considered: Migraine without Aura and Migraine with Aura. Migraine without aura often has a strict menstrual relationship: the International Headache Society classification gives criteria for Pure Menstrual Migraine and Menstrually Related Migraine. The higher prevalence of migraine among women suggests that this sex difference probably results from the trigger of fluctuating hormones during the menstrual cycle. Safe and effective contraception is essential for all women of childbearing age, but Combined Oral Contraceptives have been associated with worsening of attacks and cardiovascular risk in these patients. We analyzed characteristics, effects and benefits of progestogen-only pill, a possible alternative for contraception in women with migraine.

An Exploratory Study to Determine the Relationship between Cervical Dysfunction and Perimenstrual Migraines

PURPOSE

To determine whether an association between cervical dysfunction and perimenstrual migraines exists.

METHODS

Forty perimenstrual migraine sufferers and 46 controls were compared. Information on the participants' ages and perceptions of neck pain and stiffness were solicited. The blinded physical examination of the cervical area consisted of postural, range of motion, muscle strength, muscle length, trigger point, neural mobility, and segmental cervical joint movement assessment.

RESULTS

The migraine group had increased perception of neck pain and stiffness (p<0.001); reduced bilateral rotation (p=0.013); decreased muscle length in both trapezii, left sternocleidomastoid, and right occipitals (p=0.045); more pain on muscle stretch in both levator scapulae, both trapezii, left sternocleidomastoid, and both occipitals (p=0.013); increased trigger points bilaterally in the left trapezius (p=0.021), right trapezius (p=0.023), left sternocleidomastoid (p=0.0.004), and right sternocleidomastoid (p=0.021); reduced neural mobility with bilateral elbow lag (p=0.043); greater C4-C6 pain (p=0.045); and increased cervical stiffness in C5-C7 (p=0.023). There were no differences in posture and muscle strength. Decreased muscle length increased the risk of perimenstrual migraines 2.4-6.7 fold, reduced neural mobility 5.8-10.7 fold, and increased C7 stiffness 17.0 fold.

CONCLUSION

The results suggest that an association between cervical dysfunction and perimenstrual headaches should be further explored.

Headache classification and aspects of reproductive life in young women

OBJECTIVE

To classify headaches as a function of the menstrual cycle and to contrast aspects relating to the reproductive cycle as a function of headache type.

METHOD

Participants responded to a structured questionnaire consisting of 44 questions. Detailed headache information, enabling the classification of headaches, and questions relating to the menstrual cycle were obtained.

RESULTS

The sample consisted of 422 students. Menstrual headaches were experienced by 31.8%. Migraine without aura (MO) occurred in 13.3%, migraine with aura (MA) in 7.8%, and probable migraine in 6.4%. Women with MA were significantly more likely to have reached menarche at earlier ages than women without headaches (p=0.03). Use of a hormonal contraceptive was related to the function of having MA headaches or not.

CONCLUSION

Most female college students are affected by menstrual headaches. Although the vast majority experience MO, other headaches also occur. Women with MA are equally likely to receive hormonal contraceptives as others.

Prolactin fractions from lactating rats elicit effects upon sensory spinal cord cells of male rats

Recently it has been suggested that the neurohormone prolactin (PRL) could act on the afferent nociceptive neurons. Indeed, PRL sensitizes transient receptor potential vanilloid 1 (TRPV1) channels present in nociceptive C-fibers and consequently reduces the pain threshold in a model of inflammatory pain. Accordingly, high plasma PRL levels in non-lactating females have been associated with several painful conditions (e.g. migraine). Paradoxically, an increase of PRL secretion during lactation induced a reduction in pain sensitivity. This difference could be attributed to the fact that PRL secreted from the adenopituitary (AP) is transformed into several molecular variants by the suckling stimulation. In order to test this hypothesis, the present study set out to investigate whether PRL from AP of suckled (S) or non-suckled (NS) lactating rats affects the activity of the male Wistar wide dynamic range (WDR) neurons. The WDR neurons are located in the dorsal horn of the spinal cord and receive input from the first-order neurons (Ab-, Ad- and C-fibers). Spinal administration of prolactin variant from NS rats (NS-PRL) or prolactin variant from S rats (S-PRL) had no effect on the neuronal activity of non-nociceptive Ab-fibers. However, the activities of nociceptive Ad-fibers and C-fibers were: (i) increased by NS-PRL and (ii) diminished by S-PRL. Either NS-PRL or S-PRL enhanced the post-discharge activity. Taken together, these results suggest that PRL from S or NS lactating rats could either facilitate or depress the nociceptive responses of spinal dorsal horn cells, depending on the physiological state of the rats.

Sex differences in pain: a brief review of clinical and experimental findings

Recent years have witnessed substantially increased research regarding sex differences in pain. The expansive body of literature in this area clearly suggests that men and women differ in their responses to pain, with increased pain sensitivity and risk for clinical pain commonly being observed among women. Also, differences in responsivity to pharmacological and non-pharmacological pain interventions have been observed; however, these effects are not always consistent and appear dependent on treatment type and characteristics of both the pain and the provider. Although the specific aetiological basis underlying these sex differences is unknown, it seems inevitable that multiple biological and psychosocial processes are contributing factors. For instance, emerging evidence suggests that genotype and endogenous opioid functioning play a causal role in these disparities, and considerable literature implicates sex hormones as factors influencing pain sensitivity. However, the specific modulatory effect of sex hormones on pain among men and women requires further exploration. Psychosocial processes such as pain coping and early-life exposure to stress may also explain sex differences in pain, in addition to stereotypical gender roles that may contribute to differences in pain expression. Therefore, this review will provide a brief overview of the extant literature examining sex-related differences in clinical and experimental pain, and highlights several biopsychosocial mechanisms implicated in these male-female differences. The future directions of this field of research are discussed with an emphasis aimed towards further elucidation of mechanisms which may inform future efforts to develop sex-specific treatments.

Comparing pain sensitivity and the nociceptive flexion reflex threshold across the mid-follicular and late-luteal menstrual phases in healthy women

OBJECTIVES

Understanding the relationship between the menstrual cycle and pain can contribute significantly to our knowledge of pain processing in women. Many early studies suggested that pain sensitivity was enhanced during the luteal phase of the menstrual cycle relative to the follicular phase; however, these studies were often limited by small sample sizes, lack of ovulation verification, focus on a single pain modality, inadequate assessment of menstrual cycle regularity, and low-powered statistical methods. The current study was designed to address these limitations and examine the difference in pain processing between the mid-follicular (days 5 to 8) and late-luteal (days 1 to 6 preceding menses) phases.

METHODS

Forty-one healthy, regularly cycling women attended testing sessions that measured pain sensitivity from mechanical pain threshold, electrocutaneous pain threshold/tolerance, and ischemia pain threshold/tolerance, as well as McGill Pain Questionnaire qsensory and affective ratings of electric and ischemic stimuli. Electrocutaneous stimulation was also used to assess nociceptive flexion reflex threshold, a physiological measure of spinal nociception.

RESULTS

When analyses were limited to data collected only in the targeted menstrual phases (N=30), results indicated no menstrual phase effect on any pain outcome (all P's>0.05), with the exception of lower electrocutaneous pain thresholds during the late-luteal phase. No outcomes differed by menstrual phase in the full sample (N=41). This indicates nociceptive responding varies little between the mid-follicular and late-luteal phases.

DISCUSSION

The present study suggests that experimental pain processing does not significantly differ between the mid-follicular and late-luteal phases of the menstrual cycle in healthy women. This implies hormonal variation across these 2 phases (ie, progesterone) has a minimal effect on subjective and physiological responses to pain.

Endogenous inhibition of the nociceptive flexion reflex (NFR) and pain ratings during the menstrual cycle in healthy women

BACKGROUND

The menstrual cycle influences pain, with symptoms often increasing during the premenstrual (late-luteal) phase. Deficiencies in endogenous inhibition of afferent nociception at the spinal level might contribute to menstrual phase-related changes in pain.

PURPOSE

This study assessed whether conditioned pain modulation (CPM) of spinal nociception differs between mid-follicular and late-luteal phases.

METHODS

CPM was evoked by a blood pressure cuff affixed to the right forearm and inflated to induce ischemia in 41 healthy women during both menstrual phases. Suprathreshold electric stimuli were delivered to the left sural nerve to evoke pain and the nociceptive flexion reflex (NFR) before, during, and after forearm ischemia.

RESULTS

Forearm ischemia produced CPM of electrocutaneous pain and NFR, but inhibition did not differ across mid-follicular and late-luteal phases.

CONCLUSIONS

Mechanisms contributing to changes in experimental pain across mid-follicular and late-luteal phases in healthy women are not due to deficits in CPM of spinal nociception.

Neurological symptoms in individuals with fibrodysplasia ossificans progressiva

Fibrodysplasia ossificans progressiva (FOP), a rare, disabling condition caused by gain-of-function mutations of a bone morphogenetic protein (BMP) type I receptor, leads to episodes of heterotopic ossification and resultant immobility. Neurological problems have not been associated with FOP, but neurological symptoms are commonly reported by FOP patients. To determine the prevalence of neurological symptoms and their characteristics in individuals with FOP, we conducted a survey of the 470 patient members of the International FOP Association (IFOPA) using a questionnaire about neurological symptoms. There were 168 responses (105 females, 63 males; age 1.5-68 years) from 30 countries representing 36 % of IFOPA members. Chronic neurological symptoms were reported by 86 (51 %). Prevalence of neuropathic pain (NP) was significantly increased (P < 0.001) compared to the general population, and tenfold more common in females (15 %) than males (1.6 %). Of those with NP, 94 % reported other sensory abnormalities. Prevalence of recurrent severe headaches (HA) (26 %) was similar to that in the general population, but prevalence in females with FOP (36 %) was almost fourfold greater than in males. Prevalence of NP, HA, and other sensory abnormalities was substantially higher in post-pubertal females; 33 % reported symptoms worsened during menstrual periods. Worsening of neurological symptoms during FOP flare-ups was reported by 23 %. Three patients with FOP (1.8 %) reported myoclonus, a prevalence much greater than reported in the general population (P < 0.001). Our worldwide survey indicates that neurological symptoms are common in FOP. We speculate that these symptoms are related to effects of dysregulated BMP signaling on the central and/or peripheral nervous systems.

Epidemiology, co-morbidity, and impact on health-related quality of life of self-reported headache and musculoskeletal pain-a gender perspective

BACKGROUND

Headache and musculo-skeletal pain are major public health problems. Substantial proportions of the general population report that they experience pain problems that affect their work, daily living and social life. Epidemiological studies have consistently shown that the prevalence of most pain conditions is higher in women than in men.

DESIGN

Cross-sectional survey in the county of Uppland, Sweden, 1995. Five thousand four hundred and four completed the questionnaire (response rate=68%). In these analyses for persons aged 20-64 years 4506 were included.

RESULTS

Back pain (22.7%) and shoulder pain (21.0%) were the most commonly reported medical problems in the population with pain in arms/legs (15.7%) in fifth and headache (12.5%) in eight place. Major gender differences were found. The prevalence of pain conditions, especially headache, was higher among women. Women reported more severe pain. Co-morbidity between pain conditions and psychiatric and somatic problems was higher among women. Health-related quality of life (SF-36) differed by gender and type of pain condition. The physical dimensions of HRQoL were more affected by headache among men; psychological dimensions were more affected among women. Among both men and women, pain conditions were associated with poorer socioeconomic conditions and life-style factors but there were gender differences. Education and unemployment were important only among men while economical difficulties, half-time work and being married were associated with pain among women. Obesity, early disability retirement, long time sick-leave and lack of exercise were associated with pain conditions generally. Factors associated with pain conditions were unevenly distributed between genders.

CONCLUSION

There are major differences between men and women in the prevalence and severity of self-reported pain in the population. Biological factors may explain some of the differences but the main explanation is presumably gender disparities in work, economy, daily living, social life and expectations between women and men. Although improved working conditions are of importance, deeper societal changes are needed to reduce the inequities in pain experiences between women and men.

Precipitating and relieving factors of migraine headache in 200 iraqi kurdish patients

OBJECTIVES

To study the precipitating and relieving factors of migraine headache in a group of Iraqi Kurdish patients including the effect of fasting in Ramadan, and to estimate the percentage of family history of migraine.

METHODS

A series of 200 migraine cases from different parts of the Kurdistan region in the North of Iraq attending the out-patient Neurology clinic at Rizgary Teaching Hospital and a private Neurology clinic at Erbil City was carried out between October 2007 and May 2008 were reviewed. The precipitating factors and relieving factors for migraine headache were registered and tabulated to be compared with others. Case definition of migraine was based on the International Headache Society (IHS) criteria.

RESULTS

33% of the patients were aged between 30-39 years, while 40.5% of patients experienced their first attack aged between 20-29 years. Stress or psychological upset was the commonest triggering factor (80%), followed by increasing physical activity (68%), change in weather (65.5%), and in relation to fasting (65%). Fasting in Ramadan was a triggering factor for headaches in 65% of patients. However, there was no significant association between the triggering factors with regards to sex difference. Relief of migraine in the studied sample was achieved using NSAIDs in 50% of patients, and sleep (45.5%). Hence, 61% of the study population had positive family history of migraine, 32.5% of them reported maternal history of migraine.

CONCLUSION

Psychological upset, stress and excessive physical activity were the commonest triggering factors of migraine headache, while NSAID was the commonest relieving factor of migraine in this population. Family history was present in 61% of migraine patients based mainly from maternal root.

Soluble CD40 ligand and prolactin levels in migraine patients during interictal period

The relationship of migraine with cardiovascular diseases has been clarified by many studies, and currently, migraine is suggested to be a systematic vasculopathy. Inflammation, thrombosis and impaired vascular reactivity are the underlying pathophysiological mechanisms of the vasculopathy. In the present study, we aimed to investigate the relationship between prolactin levels and subclinical atherosclerosis risk factors such as soluble CD40 ligand (sCD40L) and high-sensitivity CRP (hsCRP) in migraine patients during interictal period. Fifty female migraine patients and age-matched 25 female control cases were enrolled in the study. Migraine diagnosis was settled according to the ICHD-II diagnostic criteria. A questionnaire was completed about the existence of vascular risk factors. Serum samples were used to measure sCD40L, hsCRP and prolactin levels. No difference was found between the prolactin levels of the migraine patients and the controls. The sCD40L levels were significantly higher in migraine patients (p < 0.001). High-sensitivity CRP levels showed no difference between the groups. There was no correlation between prolactin, sCD40L, and hs-CRP levels in migraine patients. We consider that the migraine patients are prone to subclinical atherosclerosis, but this tendency is independent of prolactin levels.

Migraine in women

Of the nearly 32 million Americans with migraine, 24 million are women. It is a disorder affecting women throughout their lifetimes, from childhood and puberty through the postmenopausal years. In childhood, before puberty girls are afflicted with migraine at approximately the same rate as boys, but after puberty, there is an emerging female predominance. Estrogen plays a key role in this epidemiologic variation but is not the only factor. There are numerous times when hormonal influences have an impact on migraine and its pattern, including menarche, oral contraceptive use, pregnancy, perimenopause, and menopause. Hence practitioners treating women with migraine need to have a clear understanding of these special considerations.

Relationship between high prolactin levels and migraine attacks in patients with microprolactinoma

The pathophysiology of pituitary-associated headache is unknown, although structural and functional features of the tumour are proposed mechanisms. The objective of this study was to evaluate whether headache in a population with pituitary micro-adenomas was related to hyperprolactinemia. We recruited 29 patients with microprolactinoma and headache: 16 with migraine (group A) and 13 with tension-type-headache (group B). The prolactin (PRL) levels measured during attacks of headache were significantly higher in nine patients (56%) of group A and in one patient (8%) of group B. In four of the nine patients of group A, PRL increased after thyrotropin-releasing-hormone (TRH) test and induced severe attacks. After dopamine-agonist (DA) treatment, the headache improved in seven (44%) patients of the group A and in two (15%) patients of the group B. Three of the four patients in whom the TRH-test induced headache attacks, improved after DA treatment. We suggest that hyperprolactinemia may contribute to development of pain in migraine subgroups and further TRH-test could be used to predict which patients could benefit by DA therapy.

The role of peer communication in the socialization of adolescents' pain experiences: a qualitative investigation

Background

Recurrent pain is a common complaint among adolescents. Children learn to resolve or cope with pain largely through family dynamics, particularly maternal influences. By adolescence, young people possess an array of pain behaviors, the culmination of multiple opportunities for modeling and reinforcement of attitudes and beliefs about pain. Adolescence is a time of increased autonomy characterized by, among other complex factors, significant increases in peer influence. Although peers are influential in health-risk behavior, little is known how peers impact adolescents' pain experience. The present study explored the role of peers in adolescents' attitudes toward pain, pain behaviors and over-the-counter analgesics.

Methods

Sixty-minute focus groups were conducted with a sample 24 junior high school students from Halifax, Nova Scotia, Canada (11 male: mean age = 13.45 years, range = 12–15 years; 13 female: mean age = 13.31 years, range = 12–15 years). Participants were randomly assigned to one of five same-gender focus groups designed to explore a wide breadth and depth of information. Sessions were run until theoretical data saturation. Textual data, from transcribed audiotapes, were analyzed with the constant comparative method.

Results

Peer influences were apparent in how adolescents communicate about pain and how those communications effect pain expression. Overt pain responses to injury were primarily contextual and depended on perceived threats to peer-time and pain severity. Adolescents were intolerant of peers' pain behaviors when the cause was perceived as not severe. These attitudes impacted how adolescents responded to their own pain; males were careful not to express embarrassing pain in front of peers, females felt no restrictions on pain talk or pain expression. Evidence for peer influence on attitudes toward OTC analgesics was apparent in perceptions of over-use and ease of access. Findings are discussed within the context of social information-processing and gender role expectations.

Conclusion

Little research has addressed how young people experience pain within the context of the psychosocial influences that dominate during adolescence. The findings provide some insight into the role of peer influences via verbal and non-verbal communication, in adolescents' pain experience. This exploratory study is a necessary first step in understanding the socialization of adolescents' pain experiences.

Efficacy of rizatriptan for menstrual migraine in an early intervention model: a prospective subgroup analysis of the rizatriptan TAME (Treat A Migraine Early) studies

OBJECTIVE

A prospective subgroup analysis of the TAME (Treat A Migraine Early) studies examined the efficacy of rizatriptan in patients treating a menstrual migraine attack.

METHODS

Both TAME studies were randomized, placebo-controlled, and double-blind. Adults with migraine were assigned (2:1) to either rizatriptan 10-mg tablet or placebo. Patients were instructed to treat within 1 hour of migraine onset and when the pain was mild. The primary endpoint was 2-hour pain freedom. The diagnosis of menstrual migraine was established according to the revised 2004 International Headache Society (IHS) diagnostic criteria. Data from both studies were pooled for logistic regression analyses. A test for interaction was performed to compare rates of 2-hour pain freedom between patients treating a menstrual and non-menstrual attack.

RESULTS

A total of 94 patients (63 in the rizatriptan group and 31 in the placebo group) met IHS criteria for menstrual migraine and treated a menstrual attack. The percentage of patients reporting 2-hour pain freedom was significantly greater for rizatriptan than for placebo (63.5% vs 29.0%; odds ratio = 4.5; 95% confidence interval: 1.7, 11.9; P = .002) in those treating a menstrual attack. In those treating with rizatriptan, the percentage of patients with 2-hour pain freedom did not statistically differ between those treating a menstrual or non-menstrual migraine attack (63.5% vs 57.5%; P = .454).

CONCLUSION

Rizatriptan 10 mg was effective for the treatment of menstrual migraine in an early intervention model, as measured by 2-hour pain freedom. Rates of 2-hour pain freedom were comparable for patients treating menstrual and non-menstrual migraine attacks with rizatriptan.

Preventative treatment of menstrual migraine

More than 20 million US women suffer with migraine, two thirds of whom experience menstrually related migraine. Estrogen plays an important role in triggering migraine, and given the numerous hormonal fluctuations throughout a woman's lifetime, there are many opportunities for a hormonal impact. Accurate diagnosis is key to initiating effective treatment, and when acute therapy fails, the unique predictability of menstrual migraine lends itself to preventative treatment.

Pharmacological approaches to managing migraine and associated comorbidities--clinical considerations for monotherapy versus polytherapy

Comorbidity is defined as an illness that occurs more frequently in association with a specific disorder than would be found as a coincidental association in the general population. Conditions that are frequently comorbid with migraine include depression, anxiety, stroke, epilepsy, sleep disorders, and other pain disorders. In addition, many common illnesses occur concomitantly (at the same time) with migraine and influence the treatment choice. Migraine management, and especially migraine prevention, can be challenging when patients have comorbid or concomitant illnesses. The objectives of this initiative are to review the literature on managing patients who have migraine and common comorbidities, present additional clinical approaches for care of these difficult patients, and evaluate the areas in which research is needed to establish evidence-based guidelines for the management of migraine with associated comorbid conditions.

Menstrual-cycle-related symptoms: a review of the rationale for continuous use of oral contraceptives

As many as 80% of reproductive-aged women experience physical changes associated with menstruation, and 20% to 40% experience menstrual-cycle-related symptoms. Decades of research in women with menstrual disorders, such as dysmenorrhea and menorrhagia, have shown that continuous use of oral contraceptives (OCs), without the hormone-free interval, is a safe and effective method to relieve these symptoms and ultimately induce amenorrhea in many women. If given the opportunity, a majority of women would opt for extended-cycle or continuous regimens, and numerous clinical trials have shown that continuous OC regimens induce amenorrhea in 80% to 100% of women by 10 to 12 months of use. For women who do not wish to become pregnant, a continuous OC regimen should be an available option.

Prolactin modulates TRPV1 in female rat trigeminal sensory neurons

Sex dependency in pain perception is well documented and is thought to be attributable to the effect of reproductive hormones on nociceptive processing. In the present study, we evaluated whether estradiol alters gene transcription in the trigeminal ganglia (TG) of ovariectomized rats (OVX). These experiments demonstrated a dramatic (40-fold) upregulation of prolactin (PRL) expression in TG by 17-beta-estradiol (E2). PRL expression was restricted to TG neurons and was highly overlapped with transient potential receptor vanilloid type 1 (TRPV1) (approximately 90%) in TG. Additionally, PRL is released from neurons during stimulation. Both forms of PRL receptors (PRLRs), short and long, were also present in TG neurons. Moreover, expression of the long PRLRs was under control of estradiol. We next evaluated the novel hypothesis that PRL acts as a neuromodulator of sensory neurons. PRL pretreatment significantly enhanced capsaicin-evoked inward currents, calcium influx, and immunoreactive calcitonin gene-related peptide release from cultured TG neurons. This PRL modulation of capsaicin responses was abolished by withdrawal of E2 from TG cultures. Biochemical analysis demonstrated that PRL increased (>50%) phosphorylation levels of TRPV1 in TG. In a behavioral test, PRL pretreatment significantly potentiated capsaicin-evoked nocifensive behavior in female rats at proestrous and in OVX rats after E2 treatment. The in vivo potentiating effect of PRL on capsaicin responses was also dependent on E2. Collectively, these data demonstrate that PRL is a novel modulator of sensory neurons tightly regulated by E2. These findings are consistent with the hypothesis that PRL could contribute to the development of certain pain disorders, possibly including those modulated by estrogen.

The lower limb flexion reflex in humans

The flexion or flexor reflex (FR) recorded in the lower limbs in humans (LLFR) is a widely investigated neurophysiological tool. It is a polysynaptic and multisegmental spinal response that produces a withdrawal of the stimulated limb and resembles (having several features in common) the hind-paw FR in animals. The FR, in both animals and humans, is mediated by a complex circuitry modulated at spinal and supraspinal level. At rest, the LLFR (usually obtained by stimulating the sural/tibial nerve and by recording from the biceps femoris/tibial anterior muscle) appears as a double burst composed of an early, inconstantly present component, called the RII reflex, and a late, larger and stable component, called the RIII reflex. Numerous studies have shown that the afferents mediating the RII reflex are conveyed by large-diameter, low-threshold, non-nociceptive A-beta fibers, and those mediating the RIII reflex by small-diameter, high-threshold nociceptive A-delta fibers. However, several afferents, including nociceptive and non-nociceptive fibers from skin and muscles, have been found to contribute to LLFR activation. Since the threshold of the RIII reflex has been shown to correspond to the pain threshold and the size of the reflex to be related to the level of pain perception, it has been suggested that the RIII reflex might constitute a useful tool to investigate pain processing at spinal and supraspinal level, pharmacological modulation and pathological pain conditions. As stated in EFNS guidelines, the RIII reflex is the most widely used of all the nociceptive reflexes, and appears to be the most reliable in the assessment of treatment efficacy. However, the RIII reflex use in the clinical evaluation of neuropathic pain is still limited. In addition to its nocifensive function, the LLFR seems to be linked to posture and locomotion. This may be explained by the fact that its neuronal circuitry, made up of a complex pool of interneurons, is interposed in motor control and, during movements, receives both peripheral afferents (flexion reflex afferents, FRAs) and descending commands, forming a multisensorial feedback mechanism and projecting the output to motoneurons. LLFR excitability, mediated by this complex circuitry, is finely modulated in a state- and phase-dependent manner, rather as we observe in the FR in animal models. Several studies have demonstrated that LLFR excitability may be influenced by numerous physiological conditions (menstrual cycle, stress, attention, sleep and so on) and pathological states (spinal lesions, spasticity, Wallenberg's syndrome, fibromyalgia, headaches and so on). Finally, the LLFR is modulated by several drugs and neurotransmitters. In summary, study of the LLFR in humans has proved to be an interesting functional window onto the spinal and supraspinal mechanisms of pain processing and onto the spinal neural control mechanisms operating during posture and locomotion.

A human experimental capsaicin model for trigeminal sensitization. Gender-specific differences

Migraine is much more common in women (18%) than in men (6%). Menstrual migraine in female migraineurs also varies from 7 to 19%. The main goals of the present study were (1) to investigate gender specific differences in an experimental capsaicin model of trigeminal sensitization (a proposed mechanism of migraine) and (2) to explore the influence of menstrual cycle phases. Twenty-eight healthy female and male volunteers were studied. Capsaicin (100 microg/0.1 ml) was injected intradermally to the forehead. Pain intensity and distribution together with the visual flare and allodynic area (central sensitization) were assessed for females (during their menstrual and luteal phases) and for males. Pain area significantly changed across the menstrual cycle with 19.2+/-2.0 cm x min at menstrual and 16.4+/-0.9 cm x min at luteal phase (P<0.001). The area was significantly larger in both phases for females compared to males (14.2+/-1.3 cm x min, P<0.0001). Flare area at menstrual phase (69.2+/-4.2 cm(2)) was significantly (P<0.0001) larger than luteal phase (58.6+/-2.1 cm(2)). Females, in both phases, showed larger flare area compared to males (44.9+/-3.6 cm(2), P<0.0001). Area of brush-evoked allodynia was also larger at the menstrual phase compared to the luteal phase (P<0.0001) and males (P<0.0001). A significant difference was found in the capsaicin-evoked pain distribution with a greater response in menstrual phase compared to the luteal phase (P<0.01) and men (P<0.0001). Capsaicin induced trigeminal sensitization and evoked gender specific sensory and vaso-motor responses, with menstruating females generally showing the strongest manifestations. The model may be further applied to explore mechanisms of human trigeminal sensitization.

Menstrual migraine

The initial treatment of menstrual migraine (MM) should be the same as that of migraine that occurs at any other time during the month and should include lifestyle modifications and the use of appropriate acute therapies aimed at decreasing attack symptoms, duration, and disability. If results of acute therapy are incomplete or unsatisfactory, then preventive strategies may be required. Comorbidities may, however, influence choice of preventive therapy or accelerate initiation of preventive therapy. Comorbid dysmenorrhea, menometrorrhagia, and endometriosis argue for early use of hormonal therapies. Hormonal strategies may be appropriate because the premenstrual decline in estradiol concentration predictably precipitates MM, and targeting and preventing this decline can decrease headache occurrence. Continuous combined hormonal contraceptives can reduce hormone fluctuations and, for some MM sufferers, can deliver more than contraceptive benefits. Nonsteroidal anti-inflammatory drugs are appropriate for treatment of co-occurring dysmenorrhea or when hormonal strategies are contraindicated; their efficacy may be caused partly by the role of prostaglandins in MM and dysmenorrhea. As with the use of hormonal therapy, use of nonsteroidal anti-inflammatory drugs allows for treatment of breakthrough headache with triptans. Results of clinical trials suggest that daily use of triptans in the menstrual window may bring about as much as 50% reduction in headache frequency, but such use still requires acute treatment of breakthrough headache and adherence to daily triptan limits. Use of this strategy requires that headache occurrence be highly predictable.