Itt írjon a(z) Migrane-ról/ről

Physiological background of migraines

By Tara Mcguinness, Marie Kidney, Lilli Shepherd

Introduction:

A migraine is a headache that can cause severe pulse or throbbing sensation, usually unilaterally. They affect a large portion of the population and are considered a public problem. In our essay, we are going to look at the physiology behind migraines and ask ourselves questions about how they are caused and what really constitutes a migraine. Migraines can be genetic or brought on by many different factors.

In our essay, we discuss the different causes of this attack. We have looked at the physiology behind migraines and what causes them to occur. We look into the science and medical studies completed on this attack of the meninges and through this task, we have researched the side effects, the symptoms, causes, and cures of this common disorder. It is clear from the various articles we studied this is a prevalent problem which affects thousands of people in their everyday lives. We also have learned who can be more susceptible to migraines and how they are medicated. Through our study of this topic, we realised how much research has been done on this disease in the last 100 years and how much continues to be done.

Contents

The physiology behind migraines:

What is a migraine?

Migraine is accepted in the scientific community to be an inherited tendency for the brain to lose control of its inputs. It is considered a neurological disorder that causes throbbing pain and can be accompanied by nausea and noise and light sensitivity. They are hereditary and can be brought on by many external environmental factors. It affects a large part of the population and is a public and societal problem. Regulation of cortical excitability plays a role. It is often thought that a migraine is a disorder of the nervous system but more recent research has revealed it is actually a comorbidity and potentially caused by a variety of different medical conditions such as neurological, psychiatric, cardio- and cerebrovascular, gastrointestinal, metaboloendocrine, and immunological conditions. It is a disease which mostly affects females with a ratio of 3:1 female-male. The most common form of migraine is a migraine without aura which is usually a unilateral severe throbbing pain accompanied by nausea and vomiting.

How does a migraine occur?

It is believed a migraine occurs by the activation of neuronal pathways within the trigeminovascular system. According to more recent research, a migraine is now thought of as a neurovascular disorder. It has been confirmed a migraine does involve the brain. It has been proven that migrainous premonitory symptoms can occur several days before the headache. There can be a plethora of different neurological symptoms whose origin are in the brain. It is believed that head pain is mediated by the activation of neuronal pathways within the trigeminovascular system. Based on research findings of the last 50–75 years, both migraine and cluster headaches are now commonly thought of as neurovascular disorders. They both certainly involve the brain; imaging studies during attacks clearly characterise activation in brain regions specific to these headaches. However, because the trigeminovascular system is involved which has specific dural vasculature innervation and migraine aura, as seen in fig 1, it is commonly thought that the vasculature is very important despite not being responsible for the attacks themselves.

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Figure 1: The Pathophysiology of a Migraine

What happens in the brain and body that causes migraines?

Old theories believed migraines were due to changes in blood flow to the brain. There is a migraine pain theory which explains that migraine pain happens due to waves of electricity from excited brain cells.

Migraines are found to be attacks on the brain due to a disorder of the brain. They are thought to appear as cycles and are influenced by genetics or the external environment. There are different phases in a migraine. In the first phase that comes before the headache, different parts of the brain begin to dysfunction and eventually evolve to the pain phase. It then follows on to the postdromal signs.

A migraine is recognised as a severe and disabling brain condition. It is one of the most disabling of all neurological disorders. Migraine is a primary headache with high levels of associated disability that can be related to a variety of symptoms and different medical conditions. Various different studies have looked at the causes of a migraine, it was popularly thought that migraines may be a vascular disorder as different studies showed activity in cranial blood vessels.

What happens in the meninges to cause migraines?

Most of the pain of a migraine is felt on the meninges. Activation of trigeminal nucleus caudalis is associated with a headache. There is a theory that migraine pain is due to the inflammation of dural meninges caused by activation of the trigeminal nerve

Why are they more common in women?

A reason for this is that some migraines are thought to be hormonally influenced by the hormones oestrogen and serotonin. All humans have these hormones but oestrogen is more prevalent in females. The female life cycle consists of many hormonal milestones, such as puberty, pregnancy and menstrual cycles and menopause. It has been recorded that migraine attacks are less frequent and less severe in the menopausal era of a women's life. And the attacks are more severe and debilitating during menstrual times. Migraine attacks at menstrual times are also recorded to be more painful and less responsive to medication versus at any other time. It is a common disease among the European population.

Different hormones have an effect on the onset of migraine pain

Phase 1: Premonitory Phase

This phase can begin as early as 3 days before a migraine occurs. This allows the patients to anticipate and predict migraine onset. During this stage the hypothalamus, limbic system and brainstem are involved. Common symptoms experienced during this stage include: food cravings, yawning, mood changes, muscle tenderness and photophobia. This study uses data from functional neuroimaging studies to show how the hypothalamus is involved in the premonitory phase. They used a marker in the blood to show the activity during a migraine by inducing the effects with glyceryl trinitrate (a chest pain medication), Maniyar et al, 2016. Studies have shown that there is a strong connection between pain transmission and autonomic function in the hypothalamus and other areas in the brain. This may account for the autonomic symptoms that are experienced in the premonitory phase, Moulton et al, 2014. Looking at these two studies there is a strong theory that the hypothalamus is involved in facilitating or increasing pain transmission during a migraine.

Phase 2: Aura

Around one-third of migraines are preceded by an aura. Aura are a group of symptoms which are associated with cortical malfunction. These malfunctions arise from cortical spreading depression (CSD). Before a headache, this occurs in the cortex. CSD is a slow wave of neuronal and glial depolarization which is followed by an inhibition of activity in the cortex. This inactivity can last from fifteen to thirty minutes. CSD begins when there is an elevation in the levels of extracellular K+. This is theorised to happen due to the continual depolarisation and repolarisation of the neurons and then this K+ further depolarises the cell that it was released from. Due to this disruption, Na+ and Ca2+ enter the cell and causes glutamate to be released, Dodick, 2018. Locally it also is shown to release ATP, potassium and hydrogen ions. These substances trigger inflammation. There are many theories that CSD activates the trigeminovascular system

Phase 3: Headache

A migraine headache is characterised by a unilateral throbbing sensation in the head. This throbbing can intensify and come with an increase in intracranial pressure. This is widely accepted to be due to trigeminovascular pathway activation. The trigeminovascular pathway conveys nociceptive information from the meninges of the brain. There are three branches of the trigeminal nerve, ophthalmic, maxillary and mandibular. The main branch that nociceptive innervation goes through is the ophthalmic branch. When the trigeminovascular pathway is activated calcitonin gene-related peptide (CGRP) and other neuropeptides are released. ATP, glutamate and K+ are also released. After this, the neurons become sensitised and the magnitude of the headache increases.

Causes:

There are many triggers for this neurological disorder.

Certain foods, fasting, alcohol, menstruation, physical exercise, emotional stress, sleep disturbances, weather changes and sensory stimuli provoke attacks according to migraineurs, Sjöstrand et al, 2010.

The opening of ATP sensitive potassium channels is a cause of migraines, Al-Mahdi Al-Karagholi et al, 2019.

Glutamate

Genetics

Migraines tends to run in families and is considered a genetic disorder.

Nitroglycerin:

Migraine symptoms:

In this section, we will discuss in-depth these symptoms and their effects on the body.

Migraine aura is a symptom that about 1 in 3 migraine sufferers get before an oncoming migraine starts. It acts as a warning that a migraine is starting. Some symptoms of aura are visual problems. These include seeing flashing lights, and patterns and having blind spots. A tingling, numbing sensation similar to pins and needles can be felt. Feeling unbalanced, having difficulties speaking, and sometimes but rarely people can lose consciousness.

There are many neurological, gastrointestinal and autonomic symptoms.

Neurological- numbness, confusion, trouble speaking, dizziness, vertigo Neurological symptoms are caused by increased excitability of the central nervous system. Hemiplegic migraines are a rare subtype of migraines that show motor weakness. tingling, numbness, lethargy and ataxia are often present along with motor weakness. Motor symptoms are unilateral, starting often in the fingertips and hand and spreading to the arm and face. Vertigo is an uncomfortable sensation where a patient's surroundings and environment seem to be spinning and moving. Attacks of vertigo are quick oncoming and can last anywhere from a few seconds to hours, and sometimes days. Loss of balance and dizziness accompany vertigo.

Gastrointestinal- stomach pain, nausea, vomiting, diarrhoea, loss of appetite Nausea and vomiting are common symptoms seen in migraine patients. It is thought to be due to connections between the nucleus tractus solitarius and the trigeminal nerve, although this is mostly speculation. Tests have shown that in patients that suffer from nausea, activity has been observed in the rostral dorsal medulla, as well as the periaqueductal grey. skipping meals can be a migraine trigger for some. Hunger and food cravings can also be seen at the onset of migraines

Autonomic- flushing, eyelid drooping and eye redness, sweating and blurry vision.

Autonomic symptoms are those that affect the ANS ( autonomic nervous system). Symptoms of autonomic dysfunction are commonly seen during migraine attacks, and can also be observed between attacks. These symptoms are more commonly seen when aura precedes a migraine attack. Dysfunction of the ANS can affect atrial and ventricular repolarization. Increased sympathetic activity can cause sinus tachycardia, but increased parasympathetic activity causes sinus bradycardia, atrioventricular block, and ST-segment and T-wave abnormalities. This can cause facial flushing and problems with eyesight.

Remedies:

Two different types of migraine therapies have been developed in recent years, preventative therapies and acute therapies.

Preventative therapies are used to reduce the frequency of migraine attacks and make them less severe and painful.

Acute therapies are used for the sake of getting rid of migraine pain. Acute therapies can provide people with rapid relief. There are pharmaceutical and non-pharmaceutical remedies to migraines. Acute migraine therapy has been divided into two groups: analgesics and NSAIDs. It has been decided oral NSAIDs and triptans, as well as other combinational medicines, have been more effective in treating migraine attacks, although dosage plays a large role in effectiveness.

Non-pharmaceutical - acupuncture, butterbur, dark rooms, certain piercings

Conclusion:

Migraines are an issue that affects such a huge proportion of the population. Research has been funded for decades on the matter and continues to be investigated. Despite this intensive research, there is still no definite cure for the ailment, just ways to reduce the effects and combat the attacks. However hopefully with continuing exploration and testing a cure will be found.

Bibliography:

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Figure

  1. Kreigler, J. S. (2018): Headache. Journal of Cleveland Clinic Journal of Medicine 9

Migrane (last edited 2022-05-07 13:20:29 by 4591E)