Goreisan regulates cerebral blood flow according to barometric pressure fluctuations in female C57BL/6J mice

Goreisan is a Kampo medicine used to treat headaches associated with climate change. Here, by using an implantable complementary metal-oxide-semiconductor (CMOS) device, we evaluated the effects of Goreisan and loxoprofen on cerebral blood flow (CBF) dynamics associated with barometric pressure fluctuations in freely moving mice. In the vehicle group, decreasing barometric pressure increased CBF that was prevented by Goreisan and loxoprofen. Notably, Goreisan, but not loxoprofen, reduced CBF after returning to atmospheric pressure. These results indicate that, unlike the mechanism of action of antipyretic analgesics, Goreisan normalizes CBF abnormalities associated with barometric pressure fluctuations by actively reducing CBF increase.

Pain and Weather associations - Action Mechanisms; Personalized profiling

It is a well-known hypothesis that weather can influence human health, including pain sensation. The primary meteorological factors are atmospheric pressure, wind, humidity, precipitation, and temperature, which vary from the climate and seasons, but the parameters of space weather (e.g., geomagnetic and cosmic ray activities) also may affect our body condition. Despite a significant number of experimental studies, reviews, and meta-analyses concerning the potential role of weather in pain sensitivity, the findings are heterogeneous and lack consensus. Therefore, rather than attempting a comprehensive analysis of the entire literature on the effects of weather on different pain types, this study highlights the potential action mechanisms of the meteorological factors, and the possible causes of the controversial results. The few data available about the individual evaluations are discussed in detail to reveal the significance of the personalized analysis of the possible relationships between the most available weather parameters and the pain scores. The use of special algorithms may enable the individual integration of different data for a precise outcome concerning the link between pain sensitivity and weather parameters. It is presumed that despite the high level of interindividual differences in response to meteorological parameters, the patients can be clustered in different groups based on their sensitivity to the weather parameters with a possible disparate treatment design. This information may help patients to control their daily activities and aid physicians to plan more valuable management for patients with pain states when the weather conditions change.

Factors Contributing to the Link between Physical Well-Being and Chronic Pain in Young People from Galicia, Northwest Spain

Introduction: The relation between physical well-being and chronic pain is complex and involves several subjective and objective covariates. We aimed to assess the role of mediator, confounder, or interactor played by covariates, including sleep quality, physical activity, perceived stress, smoking, and alcohol drinking in the relation between physical well-being and chronic pain. Method: We used Poisson regression to obtain incidence rate ratios (IRR) of the association between physical well-being and chronic pain in a cohort study carried out among university students. We applied General Structural Equation Modeling (GSEM) to assess mediation and stratum-specific analyses to distinguish confounding from interaction. We computed Relative Excess Risks due to Interaction (RERI), Attributable Proportion (AP), and the Synergy index (S) to measure additive interaction. Results: High physical well-being is related to a large decrease in the risk of chronic pain (IRR^{Total Effect} = 0.58; 95% CI: 0.50-0.81). Perceived stress mediates 12.5% of the total effect of physical well-being on chronic pain. The stratum-specific IRRs of current smokers and non-current smokers were different from each other and were larger than the crude IRR (IRR = 1.49; 95% CI: 1.24-1.80), which indicates that smoking could be both confounder and interactor. Interaction analyses showed that physical activity could act as a potential interactor (RERI = 0.25; 95% CI: 0.13, 0.60). Conclusions: Perceived stress is an important mediator of the relation between physical well-being and chronic pain, while smoking is both a confounder and an interactor. Our findings may prove useful in distinguishing high-risk groups from low-risk groups, in the interventions aimed at reducing chronic pain.

Transient activation of spinal trigeminal neurons in a rat model of hypoxia-induced headache

ABSTRACT

The mechanisms underlying headaches attributed to hypoxia are poorly known. The activation of spinal trigeminal neurons with meningeal afferent input is believed to be responsible for the generation of headaches. In the caudal spinal trigeminal nucleus of anaesthetized and ventilated rats, the spontaneous firing of neurons with input from the exposed parietal dura mater and the activity evoked by mechanical stimuli to the dura and the adjacent periosteum were recorded, whereas the O2 fraction of the ventilation gas was stepwise reduced by omitting O2 and adding nitrogen. The expiratory CO2 level, the arterial pressure, the pulse rate, and the peripheral O2 saturation (SpO2) were registered. The meningeal blood flow was recorded using laser Doppler flowmetry; video imaging was used to measure the diameter of dural and medullary arteries. Lowering O2 in the ventilation gas from hyperoxic to normoxic and finally hypoxic conditions was followed by an increase in spontaneous activity up to 300% of the initial activity in most neurons, whereas the activity in a minor fraction of neurons ceased. The mechanical threshold was reduced under hypoxia. Arterial pressure, pulse rate, and SpO2 fell during stepwise lowering of the O2 concentration, whereas the arteries of the dura mater and the medulla dilated. Increased neuronal activity in the spinal trigeminal nucleus following lowering of the inhaled O2 goes along with variations in cardiovascular parameters. The experiments may partly model the conditions of high altitudes and other hypoxic states as risk factors for headache generation.

Migraine Triggers: An Overview of the Pharmacology, Biochemistry, Atmospherics, and Their Effects on Neural Networks

We define a migraine trigger to be an endogenous agent or agency such as the menses or an exogenous agent or agency such as red wine or a drop in barometric pressure, and their ability to reduce the threshold of a migraine attack in those predisposed to migraine. This definition excludes agents with idiosyncratic mechanisms that may trigger a migrainous (migraine-like) headache in non-migraineurs such as benign cough headaches or headaches due to altitude-sickness. We also assume as axiomatic that migraine has as its basis the activation of the trigeminovascular pathway (TVP) and the key role of serotonin and the calcitonin gene-related peptide (CGRP). The network activation of the visual/auditory association cortices and the rostrodorsal pons (locus ceruleus and raphe nucleus) are also accepted as key features of activation of the TVP. In addition, we outline the role of the superior salivatory nucleus-sphenopalatine ganglion-greater superficial petrosal nerve (SSN-SPG-GSPN) arc in migraine activation.

We also explore how olfactory afferents intermingle with trigeminal nerve collaterals in the glomeruli of the olfactory bulb thus allowing volatile molecules to activate the TVP and induce a migraine. The classification of migraine triggers is complex, as there is a wide panorama of inciting agents, including atmospheric conditions, a wide-ranging variety of foods and beverages, endogenous hormonal influences, synthetic alkaloids and dyes, and volatile molecules (odorants). We will explore the high-frequency migraine-provoking agents in each category. There are exciting and intriguing hypotheses regarding the role of atmospheric chemistry when the barometric pressure drops; the role of hot, dry desert winds and lightning discharges in the generation of cations and the turnover of serotonin in the nervous system. We will explore the effects of a drop in barometric pressure on the vestibular nuclei and the modulation of sympathetically mediated pain. The role of volatile odorants and their activation of the transient receptor potential ankyrin-1 (TRPA-1) receptor will be outlined. We will streamline the highly complex role of estrogen fluctuation in the precipitation of migraine headaches, its pharmacodynamic effects, and the role of the sexually dimorphic nucleus of the preoptic area (SDN-POA) of the hypothalamus. We will also adumbrate the protean effects of alcohol and its congeners and the role of stress and sleep disturbances in the allostatic load model of salience network-pain perception.

Craniofacial sensations induced by transient changes of barometric pressure in healthy subjects – A crossover pilot study

Background:

Changes in atmospheric pressure are suggested to trigger headaches. This pilot study was made to determine craniofacial sensations accompanying short phases of changing barometric pressure.

Methods:

In a crossover design, 15 adult healthy subjects were exposed in a climate chamber to 8 min phases of barometric pressure lowering by 0, 20 and 40 hPa. The subjects rated their sensations of ear pressure, head compression and the occurrence of headache every minute on a visual analogue scale (VAS, range 0–10). Pulse rate was recorded as a parameter for autonomic functions.

Results:

Nearly all subjects experienced ear pressure and half of them compression of their head at variable degrees. These sensations started in most subjects during the phase of lowering barometric pressure and increased to an average rating of about 3 VAS when returning to ambient atmospheric pressure. Heart rate slightly decreased during this phase. Three subjects reported mild to moderate headache for various durations within these phases.

Conclusions:

Changes in barometric pressure can be associated with sensations of ear pressure and head compression and may trigger headaches. The generation of these sensations is discussed with regard to convergent trigeminal innervation of the ear, the paranasal sinuses and the cranial meninges.

The weather condition and epidemics as triggers for febrile seizure: A single-center retrospective observational study

OBJECTIVE

The objective of this study was to investigate the association between the weather and epidemic condition and risk of febrile seizures (FSs) in Japan.

STUDY DESIGN

This single-center, retrospective study included 560 children (age, 6-60 months) with FSs who were transported to our center by ambulance from January 2011 through December 2018. The weather (temperature, atmospheric pressure, relative air humidity, amount of rainfall, sunshine duration, and air concentration of nitrogen dioxide [NO₂] and sulfur dioxide [SO₂]) and epidemic (influenza virus infection, infectious gastroenteritis, and exanthem subitum) conditions in this region were compared between the periods (days or weeks) with the transportation of children with FS to our hospital and those without such transportation.

RESULTS

In the univariate analyses, neither daily or weekly weather condition nor weekly epidemic condition was correlated to FS transportation. Furthermore, the multiple logistic regression analysis suggested that epidemic influenza virus infection (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.08-1.73) and infectious gastroenteritis (OR, 1.64; 95% CI, 1.09-2.54) were the independent risk factors for FS occurrence and weather condition was not associated with FS risk.

CONCLUSIONS

Febrile seizure incidence may be increased by epidemic febrile infections but not by weather condition.

Reversible Cerebral Vasoconstriction Syndrome Triggered by Typhoon Hagibis in 2019: Report of 2 Cases

Although reversible cerebral vasoconstriction syndrome (RCVS) is a relatively rare condition, we encountered 2 consecutive patients with RCVS during Typhoon Hagibis in 2019. The first patient developed headache when the atmospheric pressure rapidly fell, and the second patient developed headache when the atmospheric pressure rapidly rose. Extreme atmospheric pressure fluctuations might induce neuronal activity in the trigeminal nucleus caudalis and sympathetic activation. Our experience with these 2 patients indicates the importance of magnetic resonance angiography for individuals with thunderclap headache during a typhoon.

Sherpas, Coca Leaves, and Planes: High Altitude and Airplane Headache Review with a Case of Post-LASIK Myopic Shift

PURPOSE OF REVIEW

High altitude headache is a common neurological symptom that is associated with ascent to high altitude. It is classified by the International Classification of Headache Disorders, 3rd Edition (ICHD-3) as a disorder of homeostasis. In this article, we review recent clinical and insights into the pathophysiological mechanisms of high altitude and airplane headache. We also report a second case of post-LASIK myopic shift at high altitude exposure secondary hypoxia. Headache attributed to airplane travel is a severe typically unilateral orbital headache that usually improves after landing. This was a relative recent introduction to the ICHD-3 diagnostic criteria. Headache pain with flight travel has long been known and may have been previously considered as a part of barotrauma. Recent studies have helped identify this as a distinct headache disorder.

RECENT FINDINGS

Physiologic, hematological, and biochemical biomarkers have been identified in recent high altitude studies. There have been recent advance in identification of molecular mechanisms underlying neurophysiologic changes secondary to hypoxia. Calcitonin gene-related peptide, a potent vasodilator, has been implicated in migraine pathophysiology. Recent epidemiological studies indicate that the prevalence of airplane headache may be more common than we think in the adult as well at the pediatric population. Simulated flight studies have identified potential biomarkers. Although research is limited, there have been advances in both clinical and pathophysiological mechanisms associated with high altitude and airplane headache.

The Influence of Weather on the Incidence of Primary Spontaneous Intracerebral Hemorrhage

BACKGROUND

Intracerebral hemorrhage has been associated with changes in various weather conditions. The primary aim of this study was to examine the collective influence of temperature, barometric pressure, and dew point temperature on the incidence of primary spontaneous intracerebral hemorrhage (sICH).

METHODS

Between January 2013 and December 2016, patients with sICH due to hypertension or amyloid angiopathy with a known time of onset were identified prospectively. Meteorological variables 6 hours prior to time of onset were obtained from the National Oceanic Atmospheric Administration via two weather stations. Using a Monte-Carlo simulation, random populations of meteorological conditions in a 6-hour time window during the same years were generated. The actual meteorological conditions 6-hours prior to sICH were compared to those from the randomly generated populations. The false discovery rate method was used to identify significant meteorological variables.

RESULTS

Time of onset was identified in 455 of 603 (75.5%) patients. Distribution curves for change in temperature, mean barometric pressure, and change in barometric pressure 6-hours prior to hemorrhage ictus were found to be significantly different from the random populations. (FDR approach P < .05). For a given change in temperature associated with intracerebral hemorrhage, mean barometric pressure was higher (1018 millibar (mb) versus 1016 mb, P = .03). Barometric pressure data was not influenced by variations in temperature.

CONCLUSIONS

We concluded that barometric pressure primarily influences the incidence of intracerebral hemorrhage. The association described in the literature between temperature and intracerebral hemorrhage is likely confounded by variations in barometric pressure.

Weather and Health Symptoms

Weather affects the daily lives of individuals. However, its health effects have not been fully elucidated. It may lead to physical symptoms and/or influence mental health. Thus, we evaluated the association between weather parameters and various ailments. We used daily reports on health symptoms from 4548 individuals followed for one month in October of 2013, randomly sampled from the entirety of Japan. Weather variables from the monitoring station located closest to the participants were used as weather exposure. Logistic mixed effects model with a random intercept for each individual was applied to evaluate the effect of temperature and humidity on physical symptoms. Stratified analyses were conducted to compare weather effects by sex and age group. The lag day effects were also assessed. Joint pain was associated with higher temperature (1.87%, 95% CI = 1.15 to 2.59) and humidity (1.38%, 95% CI = 0.78 to 2.00). Headaches was increased by 0.56% (95% CI = −0.55 to 1.77) per 1 °C increase in the maximum temperature and by 1.35% per 1 °C increase in dew point. Weather was associated with various physical symptoms. Women seem to be more sensitive to weather conditions in association with physical symptoms, especially higher humidity and lower temperature.

Seasonal Variation in the Prevalence of Common Orthopaedic Upper Extremity Conditions

Introduction  Seasonal variation in disease processes and injuries have been reported, but it is unclear if this variation exists in upper extremity disorders. The goal of this study is to characterize seasonal and weather variations in common upper extremity orthopaedic conditions. Methods  This cross-sectional study reviewed 68,943 consecutive, new patient visits from January 2010 to September 2015 for carpal tunnel syndrome (CTS), trigger finger (TF), DeQuervain's tenosynovitis (DeQ), lateral epicondylitis (LE), hand arthritis (OA), and distal radius fractures (DRF). Presentation rates for each condition were compared across month, season, and various weather parameters. Results  DRF, OA, and LE had a higher rate of presentation in the winter compared with all other seasons ( p  < 0.001). TF and DeQ showed no statistically significant seasonal differences. Higher barometric pressures were associated with higher rates of all of the diagnoses. Higher humidity was associated with lower rates of CTS, TF, DeQ, LE, and DRF ( p  < 0.001). There was no significant association between temperature levels or amount of precipitation. Discussion  Although the precise mechanism remains unclear, there does appear to be an impact of winter, increased barometric pressure, and higher humidity on presentation rates. Further studies are needed to determine more conclusively why this occurs. Level of Evidence  Level IV, cross-sectional study.

Weather as a risk factor for epileptic seizures: A case-crossover study

OBJECTIVE

Most epileptic seizures occur unexpectedly and independently of known risk factors. We aimed to evaluate the clinical significance of patients' perception that weather is a risk factor for epileptic seizures.

METHODS

Using a hospital-based, bidirectional case-crossover study, 604 adult patients admitted to a large university hospital in Central Germany for an unprovoked epileptic seizure between 2003 and 2010 were recruited. The effect of atmospheric pressure, relative air humidity, and ambient temperature on the onset of epileptic seizures under temperate climate conditions was estimated.

RESULTS

We found a close-to-linear negative correlation between atmospheric pressure and seizure risk. For every 10.7 hPa lower atmospheric pressure, seizure risk increased in the entire study population by 14% (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.01-1.28). In patients with less severe epilepsy treated with one antiepileptic medication, seizure risk increased by 36% (1.36, 1.09-1.67). A high relative air humidity of >80% increased seizure risk in the entire study population by up to 48% (OR 1.48, 95% CI 1.11-1.96) 3 days after exposure in a J-shaped association. High ambient temperatures of >20°C decreased seizure risk by 46% in the overall study population (OR 0.54, 95% CI 0.32-0.90) and in subgroups, with the greatest effects observed in male patients (OR 0.33, 95% CI 0.14-0.74).

SIGNIFICANCE

Low atmospheric pressure and high relative air humidity are associated with an increased risk for epileptic seizures, whereas high ambient temperatures seem to decrease seizure risk. Weather-dependent seizure risk may be accentuated in patients with less severe epilepsy. Our results require further replication across different climate regions and cohorts before reliable clinical recommendations can be made.

Nature's wrath-The effect of weather on pain following orthopaedic trauma

BACKGROUND

Despite frequent complaints by orthopaedic trauma patients, to our knowledge there is no data regarding weather's effect on pain and function following acute and chronic fracture. The aim of our study was to investigate the influence of daily weather conditions on patient reported pain and functional status.

METHODS

We retrospectively examined prospectively collected data from 2369 separate outpatient visits of patients recovering from operative management of acute tibial plateau fractures, acute distal radius fractures, and chronic fracture nonunions. Pain and functional status were assessed using a visual analogue scale (VAS) and the DASH and SMFA functional indexes. For each visit date, the mean temperature, difference between mean temperature and expected temperature, dew point, mean humidity, amount of rain, amount of snow, and barometric pressure were recorded. Statistical analysis was run to search for associations between weather data and patient reported pain and function.

RESULTS

Low barometric pressure was associated with increased pain across all patient visits (p=0.007) and for patients at 1-year follow-up only (p=0.005). At 1-year follow-up, high temperature (p=0.021) and high humidity (p=0.030) were also associated with increased pain. No significant association was noted between weather data and patient reported functional status at any follow-up interval.

CONCLUSIONS

Patient complaints of weather influencing pain after orthopaedic trauma are valid. While pain in the immediate postoperative period is most likely dominated by incisional and soft tissue injuries, as time progresses barometric pressure, temperature, and humidity impact patient pain levels. Affirming and counseling that pain may vary based on changing weather conditions can help manage patient expectations and improve satisfaction.

Examination of fluctuations in atmospheric pressure related to migraine

Background

Japan has four seasons and many chances of low atmospheric pressure or approaches of typhoon, therefore it has been empirically known that the fluctuation of weather induces migraine in people. Generally, its mechanism has been interpreted as follows: physical loading, attributed by atmospheric pressure to human bodies, compresses or dilates human blood vessels, which leads to abnormality in blood flow and induces migraine. We report our examination of the stage in which migraine tends to be induced focusing on the variation of atmospheric pressure.

Findings

Subjects were 34 patients with migraine, who were treated in our hospital. The patients included 31 females and three males, whose mean age was 32 ± 6.7. 22 patients had migraine with aura and 12 patients had migraine without aura. All of patients with migraine maintained a headache diary to record atmospheric pressures when they developed a migraine. The standard atmospheric pressure was defined as 1013 hPa, and with this value as the criterion, we investigated slight fluctuations in the atmospheric pressure when they developed a migraine. It was found that the atmospheric pressure when the patients developed a migraine was within 1003–1007 hPa in the approach of low atmospheric pressure and that the patients developed a migraine when the atmospheric pressure decreased by 6–10 hPa, slightly less than the standard atmospheric pressure.

Conclusion

Small decreases of 6–10 hPa relative to the standard atmospheric pressure of 1013 hPa induced migraine attacks most frequently in patients with migraine.

Weather and headache onset: a large-scale study of headache medicine purchases

It is widely recognized that weather changes can trigger headache onset. Most people who develop headaches choose to self-medicate rather than visit a hospital or clinic. We investigated the association between weather and headache onset using large-sample sales of the headache medicine, loxoprofen. We collected daily sales figures of loxoprofen and over-the-counter drugs over a 1-year period from a drugstore chain in western Shizuoka prefecture, Japan. To adjust for changes in daily sales of loxoprofen due to social environmental factors, we calculated a proportion of loxoprofen daily sales to over-the-counter drug daily sales. At the same time, we obtained weather data for the study region from the website of the Japan Meteorological Agency. We performed linear regression analysis to ascertain the association between weather conditions and the loxoprofen daily sales proportion. We also conducted a separate questionnaire survey at the same drugstores to determine the reason why people purchased loxoprofen. Over the study period, we surveyed the sale of hundreds of thousands of loxoprofen tablets. Most people purchased loxoprofen because they had a headache. We found that the sales proportion of loxoprofen increased when average barometric pressure decreased, and that precipitation, average humidity, and minimum humidity increased on loxoprofen purchase days compared to the previous day of purchases. This study, performed using a large dataset that was easy-to-collect and representative of the general population, revealed that sales of loxoprofen, which can represent the onset and aggravation of headache, significantly increased with worsening weather conditions.

Migraine headache confounding the diagnosis of acute mountain sickness

A 36-year-old man with a history of migraine headache attempted to hike from Lukla, Nepal, to Mount Everest Base Camp. On the sixth day of hiking, he had a migraine headache. After achieving resolution with typical therapies and rest, he ascended higher. Another headache developed that was interpreted to be a migraine. The headache was treated, and he ascended higher, after which severe symptoms of acute mountain sickness developed, necessitating his evacuation by helicopter. Persons with headaches in daily life may present challenges to diagnosis when traveling to high altitude. Careful evaluation and decision making are needed to achieve proper diagnosis and treatment of acute mountain sickness.

Migraine and triggers: post hoc ergo propter hoc?

The influence of environmental factors on the clinical manifestation of migraine has been a matter of extensive debate over the past decades. Migraineurs commonly report foods, alcohol, meteorologic or atmospheric changes, exposure to light, sounds, or odors, as factors that trigger or aggravate their migraine attacks. In the same way, physicians frequently follow this belief in their recommendations in how migraineurs may reduce their attack frequency, especially with regard to the consumption of certain food components. Interestingly, despite being such a common belief, most of the clinical studies have shown conflicting results. The aim of the review is to critically analyze clinical and pathophysiological facts that support or refute a correlation between certain environmental stimuli and the occurrence of migraine attacks. Given the substantial discrepancy between patients' reports and objective clinical data, the methodological difficulties of investigating the link between environmental factors and migraine are highlighted.

Atmospheric pressure and suicide attempts in Helsinki, Finland

The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods (P < 0.001), and may explain the clustering of suicide attempts. Men seem to be more vulnerable to attempt suicide under low atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects.

Effects of weather variability and air pollutants on emergency admissions for cardiovascular and cerebrovascular diseases

We examined the effect of ambient temperature, air pressure and air pollutants on daily emergency admissions by identifying the cause of admission for each type of stroke and cardiovascular disease using generalized linear Poisson regression models allowing for overdispersion, and controlling for seasonal and inter-annual variations, days of the week and public holidays, levels of influenza and respiratory syncytial viruses. Every 1°C decrease in mean temperature was associated with an increase in the daily number of emergency admissions by 7.83% (95% CI 2.06-13.25) for acute coronary syndrome (ACS) and heart failure, by 35.57% (95% CI 15.59-59.02) for intracerebral haemorrhage (ICH) and by 11.71% (95% CI 4.1-19.89) for cerebral infarction. An increase of emergency admissions due to ICH (3.25% (95% CI 0.94-5.51)), heart failure (3.56% (95% CI 1.09-5.96)) was observed at every 1 hPa decrease in air pressure from the previous days. We found stronger detrimental effect of cold on stroke than cardiovascular disease.

Chronic morphine increases Fos-positive neurons after concurrent cornea and tail stimulation

OBJECTIVE

The aim of the present study was to examine the effect of chronic morphine exposure on diffuse noxious inhibitory controls in a large population of neurons throughout the medullary dorsal horn, as assessed using immunocytochemistry for c-Fos protein.

BACKGROUND

Overuse of medications, including the opioids, to treat migraine headache can lead to progressively more frequent headaches. In addition, chronic daily headache sufferers and chronic opioid users both lack the inhibition of pain produced by noxious stimulation of a distal body region, often referred to as diffuse noxious inhibitory controls.

METHODS

In urethane anesthetized rats, Fos-positive neurons were quantified in chronic morphine and vehicle-treated animals following 52°C noxious thermal stimulation of the cornea with and without the application of a spatially remote noxious stimulus (placement of the tail in 55°C water).

RESULTS

When compared to chronic morphine-treated animals that did not receive the spatially remote noxious stimulus, chronic morphine-treated animals given corneal stimulation along with the spatially remote noxious stimulus demonstrated a 163% increase (P < .05) in the number of Fos-positive neurons in the superficial laminae of the medullary dorsal horn and a 682% increase (P < .01) in deep laminae that was restricted to the side ipsilateral to the applied stimulus. In contrast, no significant difference was found in Fos-like immunoreactivity in vehicle-treated animals given concurrent cornea and tail stimulation or only cornea stimulation in either superficial or deep laminae.

CONCLUSIONS

It is proposed that an increase in descending facilitation and subsequent loss of diffuse noxious inhibitory controls contributes to the development of medication overuse headache.

Role of glia in orofacial pain

Several acute and chronic pain conditions in the face or mouth are very common, and some are unique to the orofacial region. However, the etiology and pathogenesis of most orofacial chronic pain conditions are unresolved, and they are difficult to diagnose and manage. This article provides a brief overview of the neural mechanisms underlying orofacial pain and then highlights recent findings indicating that nonneural cells, specifically satellite cells in the sensory ganglia and astroglia and microglia cells in the central nervous system, are important players in both acute and chronic inflammatory and neuropathic orofacial pain conditions and may offer new targets for management of these conditions.

[Migraine: advances in the pathophysiology and treatment]

Cortical spreading depression (CSD) is believed to be a phenomenon underlying migraine auras. The mutations of hemiplegic migraine genes are demonstrated to cause a reduction of CSD threshold. Consistently, tonabersat, which was developed for its ability to inhibit CSD, showed a preventive effect on attacks of migraine with aura. Besides, CSD has also been reported to activate the trigemino-vascular system, which subsequently causes migraine headache. The transient receptor potential cation channel, subfamily V, member 1 (TRPV1) receptor is known as one of the nociceptive receptors, and exists in the dura mater and the trigeminal ganglion. We demonstrated that the dural TRPV1 receptor conducts pain sensation to the trigeminal nucleus caudalis via the trigeminal ganglion, which implies possible contribution of the TRPV1 receptor to migraine headache. Also our recent data have raised the possibility that the TRPV1 receptor may play a pivotal role for the chronification of migraine. Furthermore, the TRPV1 receptor regulates the release of calcitonin gene-related peptide (CGRP). CGRP has been recognized to be associated with migraine because of its potent effect for dilation of intracranial and extracranial blood vessels. Some newly developed CGRP receptor antagonists have revealed the efficaciousness for acute migraine attacks. The present review discusses the relevance of recent advance of basic migraine research to future migraine treatment.

Influence of barometric pressure in patients with migraine headache

OBJECTIVE

Barometric pressure has been reported as a triggering and exacerbating factor in migraine headaches, although there are few reports concerning the association of weather change and migraine headache. The relationship between barometric pressure changes and migraine headaches was prospectively examined.

METHODS

A total of 28 migraine patients who lived within 10 km of the Utsunomiya Local Meteorological Observatory kept a headache diary throughout the year. Daily and monthly mean barometric pressure data of the Utsunomiya Local Meteorological Observatory were obtained via the homepage of the Meteorological Office.

RESULTS

The correlation between headache frequency obtained by the headache diaries for 1 year and changes in the barometric pressure during the period of 2 days before and 2 days after the headache onset were evaluated. The frequency of migraine increased when the difference in barometric pressure from the day the headache occurred to the day after was lower by more than 5 hPa, and decreased when the difference in barometric pressure from the day the headache occurred to 2 days later was higher by more than 5 hPa. Of 28 patients, weather change was associated with migraine headache development in 18 (64%) patients, 14 of which reported low barometric pressure to be a cause of headache. There was no association between the monthly mean barometric pressure and headache frequency throughout the year.

CONCLUSION

Barometric pressure change can be one of the exacerbating factors of migraine headaches.

Lowering barometric pressure aggravates depression-like behavior in rats

Weather change has been known to influence the condition of patients with mood disorder. However, no animal studies have tested the influence of climatic factor on emotional impairment. In this study, we examined the effect of lowering barometric pressure (LP) in a climate-controlled room on immobility time in the forced swim test in rats, which is considered to be an index of behavioral despair (helplessness). When the rats were exposed to daily repeated forced swim, the immobility time gradually increased. This increment was inhibited by repeated administration of the antidepressant imipramine, suggesting that the immobility is an anxiety/depression-like behavior. LP exposure (20 hPa below the natural atmospheric pressure) further increased immobility time in rats submitted to repeated forced swim. In another series of experiments, we examined the effect of daily repeated LP exposure on the maintenance of immobility after withdrawal from 6-day repeated forced swim. When the rats were challenged with forced swim under natural atmospheric pressure on day 14 after the withdrawal, immobility time was significantly longer than in non-conditioned rats. These findings demonstrated that LP in the range of natural weather change augmented the depression-like behavior in rats.