Migraine as a visceral pain

The evolutionary meaning of migraine

INTRODUCTION

Migraine's astonishing prevalence and preserved genetic background contrast with the definition of a disease and the biological meaning of experiencing recurrent, severe headache attacks is still puzzling.

METHODS

To provide a comprehensive explanation of the migraine evolutionary meaning, we review (i) the putative role of the autonomic nervous system in migraine attacks, (ii) the inter-ictal autonomic, functional, and metabolic signature of migraine patients, (iii) the bio-behavioral perspective of pain, and (iv) the allostatic perception of migraine chronification.

RESULTS

Migraineurs have inter-ictal cortical hyperexcitability and metabolic dysfunction that predisposes to brain energetic imbalance. Multiple precipitating factors may lead to brain energy consumption over the migraine attack generation threshold. In response, the brain engenders adaptive, evolutionary conserved, autonomic-behavior responses through the antidromic activation of the trigeminovascular system. The sickness behavior and severe pain experienced during migraine attacks result in avoiding mental and physical activity, allowing brain energy restoration. Chronic exposure to stressors may result in an allostatic overload, leading to maladaptive chronic activation of these responses. In this bio-behavioral perspective, the chronification of migraine should be envisioned as a pathological process, whereas the migraine itself should not.

CONCLUSION

Migraine has an evolutionary (Darwinian) meaning.

Involvement of Intestinal Enteroendocrine Cells in Neurological and Psychiatric Disorders

Neurological and psychiatric patients have increased dramatically in number in the past few decades. However, effective treatments for these diseases and disorders are limited due to heterogeneous and unclear pathogenic mechanisms. Therefore, further exploration of the biological aspects of the disease, and the identification of novel targets to develop alternative treatment strategies, is urgently required. Systems-level investigations have indicated the potential involvement of the brain–gut axis and intestinal microbiota in the pathogenesis and regulation of neurological and psychiatric disorders. While intestinal microbiota is crucial for maintaining host physiology, some important sensory and regulatory cells in the host should not be overlooked. Intestinal epithelial enteroendocrine cells (EECs) residing in the epithelium throughout intestine are the key regulators orchestrating the communication along the brain-gut-microbiota axis. On one hand, EECs sense changes in luminal microorganisms via microbial metabolites; on the other hand, they communicate with host body systems via neuroendocrine molecules. Therefore, EECs are believed to play important roles in neurological and psychiatric disorders. This review highlights the involvement of EECs and subtype cells, via secretion of endocrine molecules, in the development and regulation of neurological and psychiatric disorders, including Parkinson’s disease (PD), schizophrenia, visceral pain, neuropathic pain, and depression. Moreover, the current paper summarizes the potential mechanism of EECs in contributing to disease pathogenesis. Examination of these mechanisms may inspire and lead to the development of new aspects of treatment strategies for neurological and psychiatric disorders in the future.

Migraine Triggers and Oxidative Stress: A Narrative Review and Synthesis

BACKGROUND

Blau theorized that migraine triggers are exposures that in higher amounts would damage the brain. The recent discovery that the TRPA1 ion channel transduces oxidative stress and triggers neurogenic inflammation suggests that oxidative stress may be the common denominator underlying migraine triggers.

OBJECTIVE

The aim of this review is to present and discuss the available literature on the capacity of common migraine triggers to generate oxidative stress in the brain.

METHODS

A Medline search was conducted crossing the terms "oxidative stress" and "brain" with "alcohol," "dehydration," "water deprivation," "monosodium glutamate," "aspartame," "tyramine," "phenylethylamine," "dietary nitrates," "nitrosamines," "noise," "weather," "air pollutants," "hypoglycemia," "hypoxia," "infection," "estrogen," "circadian," "sleep deprivation," "information processing," "psychosocial stress," or "nitroglycerin and tolerance." "Flavonoids" was crossed with "prooxidant." The reference lists of the resulting articles were examined for further relevant studies. The focus was on empirical studies, in vitro and of animals, of individual triggers, indicating whether and/or by what mechanism they can generate oxidative stress.

RESULTS

In all cases except pericranial pain, common migraine triggers are capable of generating oxidative stress. Depending on the trigger, mechanisms include a high rate of energy production by the mitochondria, toxicity or altered membrane properties of the mitochondria, calcium overload and excitotoxicity, neuroinflammation and activation of microglia, and activation of neuronal nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. For some triggers, oxidants also arise as a byproduct of monoamine oxidase or cytochrome P450 processing, or from uncoupling of nitric oxide synthase.

CONCLUSIONS

Oxidative stress is a plausible unifying principle behind the types of migraine triggers encountered in clinical practice. The possible implications for prevention and for understanding the nature of the migraine attack are discussed.

Randomized controlled trial of treatment expectation and intravenous fluid in pediatric migraine

OBJECTIVE

(1) The primary objectives were (1) to assess the response to intravenous (IV) fluid in children presenting to the ED with migraine and; (2) to assess the effect of treatment expectation on the response to I.

BACKGROUND

Despite a lack of evidence for the practice, many emergency department (ED) migraine treatment protocols include a bolus of IV fluid. This study assessed the overall response to IV fluid hydration and the effect of expected medication treatment on the pain response among children and adolescents with migraine in an urban ED.

METHODS

A single-blind, randomized parallel arm trial of 10 mL/kg IV 0.9% sodium chloride for children and adolescents aged 5-17 years presenting to a pediatric ED with migraine. Patients were randomized into group A (no expectation of medication in combination with IV fluid) and group B (expectation that medication may be given simultaneously). All participants were treated with standard care following the 30-minute assessment.

RESULTS

Forty-seven participants were randomized and 2 were excluded; mean age was 13.3 years and 31 (67.4%) were females. Demographics and baseline characteristics were similar between groups. Overall, there was no statistically significant difference for the primary outcome - change from baseline on the visual analog scale (VAS) at 30 minutes with a mean change of -12.3 mm (standard deviation [SD] 17.9) in group A and -12.7 mm (SD 13.2) in group B (P = .936). The standardized difference between the 2 means (Cohen's d effect size) was low at 0.024 (95% confidence interval [CI] -0.56 to 0.61). Overall, complete headache relief was observed in only 1 participant; 16 of 45 (35.6%; 95% CI 21.8 to 51.2) had a reduction in headache of 33% or more and 8 of 45 (17.8%; 95% CI 6.1 to 29.4%) had a minimum clinical significant difference of 30 mm or more on VAS with 4 in each group. Thirteen of 39 patients with follow-up data (33.3%; 95% CI 19.1 to 50.2%) reported a moderate or severe headache at the 24-hour follow up with no difference between groups; only 3 patients returned to the ED. One participant reported a minor IV-related adverse event.

CONCLUSIONS

The overall decrease in pain with IV fluid is small and clinically insignificant. Treatment expectation did not significantly influence headache relief at 30 minutes with IV fluid hydration in children or adolescents with migraine in the ED. The average relief of headache with IV fluid alone was small; however, a clinically meaningful response was observed in 17.8%. Recurrence of headache is common in 33% after ED discharge.