Migraine
Overview
Migraine is a genetically influenced chronic disorder characterised by episodes of moderate-to-severe throbbing headache, most often restricted to one side. Each attack lasts for 4 to 48 hours and is often associated with nausea, vomiting, vertigo, hypersensitivity to light, sound, smell, and difficulty in concentrating. Migraines can start at any age, but they often begin during late childhood or early adolescence. In some cases, migraines can start in early childhood or even later in life. However, migraines are more common in people between the ages of 15 and 55. The age of onset can vary depending on various factors, including genetics, lifestyle, and other medical conditions.
Classification of Migraines
According to International Headache Society, migraines can be classified into several subtypes:
Migraine with aura
Migraine headache that is often characterised by a set of symptoms that occur before the headache begins. These symptoms are known as an "aura" and can include visual, sensory, speech and language, motor, brainstem, and retinal.
Migraine without aura
Migraine headache that is characterised by the absence of aura. This is the most common type of migraine.
Chronic migraine
Headache occurring on 15 days or more per month for more than 3 months, which, on at least 8 days per month, and has the features of migraine headache.
Clinical progression of migraine
Migraine Prodrome
About 60% of patients with migraine reported that at least some of their attacks are preceded by neck stiffness, food cravings, vague symptoms such as fatigue or mood changes from 2 up to 48 hours prior to the onset of migraine headache.
Centrepiece of Migraine – Headache
Migraine headaches have different intensities and characteristics as described by migraine patients. In most cases, the pain is sufficient to disrupt daily activities, although the pain ranges from merely annoying to disabling. The intensity may also vary from attack to attack, and the severity of headache is often worsened by routine physical activity.
According to patients, migraine headaches are typically unilateral, or at least more severe on one side. However, there are also patients complaining of bilateral headaches, or even holocephalic. The quality of the pain may be throbbing, pressure-like, or a combination of both. The throbbing pain tends to appear only as the intensity of the pain reaches a moderately severe level.
Most of headache episodes in adults persist for at least four hours and may continue for up to three days. In each migraine headache attack, the headache generally escalates from mild pain to a more severe level over an hour or two. In many patients, severe level headaches are associated with nausea, prolonged vomiting, and retching. In addition, migraine headaches are frequently accompanied by increased sensitivity to light, sound and smells, in which the headaches are worsened by the sudden input of light, sound or smells.
Migraine Resolution
The resolution phase of a migraine is the period when the headache and associated symptoms gradually subside, and the person begins to feel better. The length of the resolution phase can vary from person to person, but it typically lasts several hours to a few days. During the resolution phase, the pain and discomfort associated with the migraine headache gradually fade away. The person may begin to feel more alert and able to resume their normal activities. Nausea, vomiting, and sensitivity to light and sound may also start to improve during this phase.
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The final phase of resolution is known as the postdrome phase, which can last for several hours to a few days. Migraineurs may still feel fatigued or have difficulty concentrating even after headache has resolved, and they may present with symptoms like variable mood changes, including both depressed and euphoric moods, persistent soreness in the area affected by the headache (hypersensitivity), or transient pain with sudden head movement or trivial stimulations, such as shaving or combing of hair (allodynia). Patients often describe the postdrome phase as migraine hangover.
Grades of Migraines
Triggers of migraine headaches
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There are many possible triggers of migraine headache, but the triggers vary according to people.
Some common triggers include:
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Menstrual cycle
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Weather change
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Sleep pattern disturbances
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Bright or glaring light
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Strong smells
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Physical exertion
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Loud noises
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Stress
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Alcohol
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Poor postures
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Specific foods
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Depression
Pathogenesis of Migraine
Migraine starts with unknown root cause(s) triggering a wave of depolarisation in a unilateral region of the cortex, with associated increased blood flow to that region to match with the metabolic demand of the region. As the depolarising wave spreads to other cortical regions, the original cortical region undergoes repolarisation and blood flow reduces correspondingly. The spreading of wave of depolarisation across the surface of the brain is called the “cortical spreading depression” (CSD). It is believed that CSD creates auras via unknown mechanism and plays a role in the development of migraine headaches.
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If the depolarising wave passes over the axons of the Trigeminal nerve, these axons will release neuropeptides antidromically. This is known as the Trigemino-vascular theory. The neuropeptides like serotonin are released directly on dural blood vessels causing neurogenic inflammation at the site. This leads to peripheral sensitisation, in which the response threshold of the primary nociceptive neurons in the dural blood vessels is reduced. Consequently, normal pulsations of intravascular pressure inappropriately activate the dural nociceptors, resulting in unilateral throbbing headache.
Treatment
Mild migraine :
First indication of an attack and repeated 4 to 6 hourly abort and suppress most mild attacks
Mild migraine:
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Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, naproxen, diclofenac, indomethacin either alone or combined with paracetamol, codeine, diazepam, or another sedative or another antihistamine
Migraineurs presented with nausea, vomiting and gastric stasis :
Metoclopramide, domperidone and prochlorperazine are common choices.
Simple analgesics are usually not effective for moderate migraine headaches, but stronger NSAIDs or the combination of NSAIDs and simple analgesics mentioned above are found to be beneficial in many cases. The remaining are treated with an ergot preparation or sumatriptan. In moderate cases, anti-emetics are mostly needed. Migraineurs are only advised to start prophylactic treatment when the attacks are more than 2-3 per month.
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In severe migraine headaches, analgesics or NSAIDs or their combination are not adequate to relieve the pain, only ergot alkaloids or sumatriptan are effective and are often prescribed along with anti-emetics. Prophylactic therapy lasting for 6 months, or more is recommended in severe migraine.
References
Blau, J. N. and Dexter, S. L. (1981). The site of pain origin during migraine attacks. Cephalalgia 1(3): 143–147.
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Dalkara, T., Moskowitz, M. A. (Ed.). (2017). Neurological Basis of Migraine. John Wiley & Sons, Inc.
The International Classification of Headache Disorders 3rd edition. (2021). International Headache Society. Retrieved from https://ichd-3.org/
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Tripathi, K. D. (2008). Essentials of Medical Pharmacology (6th ed.). Jaypee Brothers Medical Publishers (P) LTD.
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Yan, Y. (2012, December 22). Migraines and Auras: Pathogenesis and Clinical Findings. The Calgary Guide. Retrieved from https://calgaryguide.ucalgary.ca/migraines-and-auras-pathogenesis-and-clinical-findings/