Headache
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Glutamate (Glu) and glutamine (Gln) are strongly compartmentalized (in neurons for Glu and in astrocytes for Gln). The visual cortex is the brain region with a higher neuron/astrocyte ratio (the highest neuronal density and the relatively lowest density of astrocytes). Elevations in extracellular Glu or potassium above certain thresholds are likely candidates to be the final common steps in the multiple distinct processes that can lead to cortical spreading depression. Astrocytes play a key role in this phenomenon, by acting as a sink for extracellular Glu and potassium, as well as generally acting as a buffer for the ionic and neurochemical changes that initiate and propagate cortical spreading depression. ⋯ These findings are consistent with glutamatergic differences in migraine patients during the interictal period compared with healthy controls. We hypothesize that an increased Glu/Gln ratio could arise from neuronal-glial coupling of glutamatergic metabolism differences or an increased neuron/astrocyte ratio in the OC.
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During the past decade, the introduction of the second edition of the International Classification of Headache Disorders (ICHD-II) and the initiation of active campaigns to increase awareness of the high magnitude, burden, and impact of migraine have stimulated numerous studies of population-based data on the prevalence, correlates, and impact of migraine. ⋯ This review demonstrates that the descriptive epidemiology of migraine has reached its maturity. The prevalence rates and sociodemographic correlates have been stable across 50 years. These developments justify a shift in efforts to the application of the designs and methods of analytic epidemiology. Retrospective case-control studies followed by prospective cohort studies that test specific associations are likely to enhance our understanding of the predictors of incidence and progression of migraine, subtypes of migraine with differential patterns of onset and course, and specific environmental exposures that may have either causal or provocative influences on migraine etiology.
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Most women have used at least 1 method of contraception during their reproductive years, with the majority favoring combined oral contraceptives. Women are often concerned about the safety of their method of choice and also ask about likely effects on their pre-existing headache or migraine and restrictions on using their headache medication. While there should be no restriction to the use of combined hormonal contraceptives by women with migraine without aura, the balance of risks vs benefits for women with aura are debatable. ⋯ Low-dose pills currently used are considerably safer than pills containing higher doses of ethinylestradiol but they are not risk-free. This review examines the evidence available regarding the effect that different methods of contraception have on headache and migraine and identifies strategies available to minimize risk and to manage specific triggers such as estrogen "withdrawal" headache and migraine associated with combined hormonal contraceptives. The independent risks of ischemic stroke associated with migraine and with hormonal contraceptives are reviewed, and guidelines for use of contraception by women with migraine are discussed in light of the current evidence.
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The expansion of technologies available for the study of migraine pathophysiology has evolved greatly over the last 15 years. Two areas of rapid progress are investigations focusing on the genetics of migraine and others utilizing novel functional neuroimaging techniques. ⋯ At the same time, neuroimaging studies have provided novel insights into the altered neuronal and network dynamics of the migrainous brain. These 2 parallel approaches provide complementary insights into the complexity and heterogeneity of migraine.
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We aimed to identify clinical features in patients with severe headaches that predicted obstructive sleep apnea (OSA) and determine clinical and sleep study characteristics that predicted headache improvement with continuous positive airway pressure (CPAP). ⋯ Headache patients should be evaluated for the presence of OSA. Treating OSA improves headaches in some patients.