A migraine is a medical condition which usually causes a pounding, throbbing headache on one side of the head. The pain may be very bad and hurt so much that a person may have a hard time doing anything. While most people who have migraines get a headache, not everyone does. There are different kinds of migraines, and some do not cause a headache but do have other symptoms.

Most migraines cause a headache and nausea and might make the person dizzy or very sensitive to bright lights or loud noises. Some people have "auras" before a migraine starts, which means their ability to see becomes different. They may see funny patterns, have blurry vision, or may not be able to see at all. Other senses can change before or during a migraine, and the person may sense funny smells or tastes. Migraines can last a long time. Migraines usually last between four and 72 hours.

Migraines have been classified, based on how often they happen in a month: If a person has a headache for less than fifteen days, the migraine is called episodic migraine (EM).  If it happens more than fifteen days, it is called chronic migraine (CM). Chronic means it happens over a long amount of time. Some people who start off getting episodic migraines may start to get chronic migraines later. Chronic migraine then may revert or go back to episodic migraine.

Scientists have discovered that something called CGRP is the cause of migraines. CGRP stands for "calcitonin gene-related peptide". CGRP is a protein that causes migraines when it is released around the brain. What CGRP does, is that it causes a lot of inflammation in the meninges, a covering above the brain.

There are different risk factors which make a person more likely to have migraines. Being a female is a risk factor, and so is having family members who had migraines. For a person who has migraines, there are different trigger factors which may set off a migraine attack. In a large group of females who have migraines, one of the main trigger factors is when the amount of the hormone estrogen in their body either drops too low or fluctuates (goes up and down).

The World Health Organization says that migraine headache is the most costly brain problem for treatment and disability in the European Union and the United States.

Types

Migraine with aura
 Acephalgic migraine, also called a silent migraine, is a kind of migraine with aura but without the head pain. This type of migraine usually starts sometime during middle-age, which is after a person is 40 years old, and becomes more common as a person gets older. Unlike other migraines, males have acephalgic migraines more often then females do.
 Basilar-type migraine is a type of migraine with aura that causes headache usually in the occipital region of the brain with neurological symptoms that is believed to come from the brainstem, occipital cortex, and cerebellum and/or affects both hemispheres of the brain at the same time. Most people who have basilar-type migraine also experience migraines with aura without the basilar symptoms. This type of migraine usually more common in people under age 20 and young females.
 Familial hemiplegic migraine (FHM) is a type of migraine with aura that also may cause paralysis on one side of the body.  When the migraine stops, the person can move normally again.
 Retinal migraine has repeated times of vision loss in one eye, that may happen before or during a headache. People who have retinal migraines usually have a history of having one of the other more common types of migraine.

Migraine without aura
 Menstrual migraine or catamenial migraine is a type of migraine that happens perimenstrually, which means around the time of menstruation during a woman's monthly menstrual cycle. Menstrual migraine is  usually a migraine without aura, but sometimes a menstrual migraine with aura happens.  About 7%-14% of women have migraines exclusively at the time of menstruation.  These are considered true menstrual migraines. Most female migraneurs experience migraine attacks at all times during the menstrual cycle, with an increased number perimenstrually.  These are referred to as menstrually related or menstrually triggered migraine. Both true menstrual migraines and menstrually related migraines are categorized under menstrual migraine.
 The role of estrogen
Estrogen is a hormone that is mostly made in a woman's ovaries. There are three types of estrogen: estrone, estradiol and estriol. In women who have migraines it is usually connected with their menstruation cycle. About 60% of women have these menstrual or menstrually-related migraines and the main trigger is believed to be reduced circulating estrogen levels, i.e. the amount of estrogen in the body, specifically estradiol. In some cases, fluctuation (going up and down) in the amount of circulating estrogen levels may trigger a migraine, i.e. not only too little but sometimes too much estrogen may trigger a migraine.

Childhood periodic syndromes

Childhood periodic syndromes are a group of migraine syndromes that children may have. When a child has one of these child periodic syndromes there is a greater chance that they will get one of the other, more common types of migraines when they become adults.

Abdominal migraine is a kind of migraine which causes a very bad pain in the area of the abdomen, usually around the 'belly-button' which is called the periumbilical area. Abdominal migraine usually affects children starting at about age 7, but it may affect younger children and older children, and it may also sometimes affect adults.

Benign paroxysmal vertigo of childhood (BPVC for short): (this means harmless dizziness, that happens again and again and happens suddenly) is a medical condition which occurs in children usually starting between two and five years of age; it often disappears by the age of eight. BPVC causes vertigo.

Cyclic vomiting syndrome or cyclical vomiting syndrome (CVS), is a medical condition whose main symptoms are nausea and repeated vomiting. CVS happens more often in children, but it can occur at any age.

Chronic vs. episodic migraine

Episodic migraine (EM) is when a person has migraine symptoms for 14 days or less in one month, while chronic migraine (CM) is when a person has migraine symptoms for 15 or more days in one month. When compared to persons with episodic migraine, those with CM where less likely to have full-time jobs and had a larger risk of headache-related disability. Persons with CM are almost twice as likely to have anxiety, chronic pain, and/or depression; they also have a 40% greater chance of having heart disease and angina and are 70% more likely to have a history of stroke.

About 7.68% of total migraine cases are chronic migraines and about 1% of people in the United States have CM, with a higher rate among females, middle-aged people, and in those households that had the lowest annual income. (The American Migraine Prevalence and Prevention Study)

Aura

Aura (from the Greek word for breeze) is the word used to describe a series of neurological symptoms that may begin before an epileptic seizure or a migraine headache. About 15% of people who have a migraine will have the kind with an aura. The symptoms may include visual problems such as scotomas (losing vision for a short time, seeing zig-zag lines or floating spots etc.), vertigo, a ringing noise in the ears (tinnitus) and problems speaking.

Scotoma (came from the Greek word for darkness: skotos): a blind spot or area of reduced vision surrounded by a normal visual field. i.e.: A person can see normally except where the scotoma is. Scotomas may affect one or both eyes and be either and be either absolute where nothing can be seen within the scotoma or, relative with some ability to see within the area of the scotoma.

Scotomas may also have different patterns and shapes like the fortification scotoma; it is called fortification because it looks like the outline of an old fort. Scotomas can start of small and then get bigger, move around to different parts of a person's visual field, and they can also look like flickering lights.

Risk factors and triggers

In medicine a factor is a substance, a condition or an activity, or a lack thereof that increases the chance of a certain outcome or condition happening. If it increases the chance of something unhealthy it is a risk factor. A trigger factor or 'trigger' for short is a factor that may cause an activity or the signs and/or symptoms of a medical condition to begin.

Risk factors
 Gender: Women are three times more likely to have migraine headaches than men.
 Family history: A person has more of a chance of getting migraines if one of their parents has had them. The International Headache Consortium are doctors from a lot of different countries who study headaches and what causes them. They have found four genetic variations - these are differences in a persons genes - that are risk factors for migraine without aura in people who have these differences. Two of these genetic variations had already been shown to play a role in migraine with aura.
 Hormonal changes
 Obesity: has shown to be a risk factor for chronic migraine not episodic migraine.
Triggers
 Dietary habits: fasting, dehydration, or skipping meals.
 Diet: Eating certain foods such as those that contain tyramine which is found in certain foods and is the end result of the natural breakdown of the amino acid tyrosine. Various food contain tyramine such as aged cheeses, smoked fish, some kinds of beer. Tyramine as a trigger for migraine is thought to effect less than 10% of people with migraines.

Diagnosis

There are no specific tests to diagnose migraine but a doctor may use different tests to rule out other causes for a person's symptoms. The diagnosis of migraine is a clinical diagnosis which means it is based upon a person's medical history that a person reports to the doctor. The medical history for a possible migraine diagnosis which can be called the headache history includes information such as:
 Does anyone else in the person's family have medical problems. If so what kind?
 What are all the symptoms you have?
 At what age did the symptoms first start?
 How often do the headaches and/or other symptoms occur?
 How long do the symptoms last?
 Where is the pain? Unilateral: either left or right side of the head - bilateral: both left and right sides

Differential diagnoses
Differential diagnoses are different medical disorders which may cause the same symptoms. Before a doctor makes a final diagnosis, which means they are sure of what medical disorder is causing the problem, they think of what other medical conditions have the same or almost the same symptoms, and make sure it's not one of them.
 Brain tumor
 Cluster headache
 Sinusitis
 Stroke
 Subarachnoid hemorrhage
 Tension headache
 Vascular pathologies: medical conditions that effect the vascular system such as arteriovenous malformation

Disorders that often occur with migraine

Often, having one medical condition makes it more likely a person will also have one or more other medical or psychiatric disorders. These other disorders are the "comorbid disorders" or "comorbidities". There are various comorbid medical and psychiatric conditions associated with migraines. The treatment and prognosis (if a disease gets better, worse or stays the same over time) of migraine  is affected by the comorbid disorders which may be present and/or the chance of getting comorbid disorders.
Asthma

Raynaud’s disease: is a circulatory disorder in which the smaller arteries that supply blood to the extremities - most often the hands, but it may also affect the, toes, the tip of the nose and the ears - become narrower reducing blood flow. This causes the extremities to become numb and to be cooler than the core body temperature. It can be triggered by exposure to stress and cold.
Epilepsy
Fibromyalgia

Comorbid psychiatric conditions
Major depressive disorder
Anxiety
Bipolar disorder

Complications of migraine
In medicine, a complication is a problem that happens because of, a procedure (like surgery), treatment (like medication), or illness (like migraines).
 Chronic migraine
 Status migrainosus is the term used to describe a severe migraine attack which lasts more than 72 hours straight.
 Persistent aura without stroke
 Migraine stroke
 Migraine-triggered seizures

Epidemiology

In medicine epidemiology is the study of what causes diseases and medical conditions, how often they happen, where they happen and who they happen to.

Migraine is more common among boys than girls until the beginning of puberty when girls start getting migraines more often than boys. By the later part of the teenage years girls get migraines almost twice as much as boys do. The number of people who get migraines is highest between the ages of 25 to 55 years in both men and women, after which, the risk of getting migraines get lower as a person gets older.

Between 65-75% of adult migraine sufferers are women and of these women, about two-thirds have menstrual migraines. Migraines are more common in people who make less money, there may be different reasons why such as stress.

About two-thirds of migraines are migraines without aura and the remaining one-third of cases are migraine with aura.

History
Symptoms that mimic those of migraines have been recorded in various cultures throughout written history. The first known mention was found on cuneiform tablets from Babylonia dating to 2000-1880 B.C.E. A treatment for migraine can be found in the Ebers Papyrus, an Ancient Egyptian medical text named after George Ebers, the  German Eygptologist who discovered them. In the ancient text dated to 1552 B.C.E. migraine is refereed to as "suffering in half the head".

The Ancient Greek physician Aretaeus of Cappadocia's description of a type of headache he dubbed heterocrania is considered a description of migraine.

References

 
Pain
Syndromes