Migraine

Migraine (UK: /ˈmiːɡreɪn/, US: /ˈmaɪ-/) is a complex neurological disorder characterized by episodes of moderate-to-severe headache, most often unilateral and generally associated with nausea, and light and sound sensitivity. Other characterizing symptoms may include vomiting, cognitive dysfunction, allodynia, and dizziness. Exacerbation or worsening of headache symptoms during physical activity is another distinguishing feature.

Up to one-third of people with migraine experience aura, a premonitory period of sensory disturbance widely accepted to be caused by cortical spreading depression at the onset of a migraine attack. Although primarily considered to be a headache disorder, migraine is highly heterogenous in its clinical presentation and is better thought of as a spectrum disease rather than a distinct clinical entity. Disease burden can range from episodic discrete attacks to chronic disease.

Migraine is believed to be caused by a mixture of environmental and genetic factors that influence the excitation and inhibition of nerve cells in the brain. The accepted hypothesis suggests that multiple primary neuronal impairments lead to a series of intracranial and extracranial changes, triggering a physiological cascade that leads to migraine symptomatology.

Initial recommended treatment for acute attacks is with over-the-counter (OTC) analgesics (pain medication) such as ibuprofen and paracetamol (acetaminophen) for headache, antiemetics (anti-nausea medication) for nausea, and the avoidance of migraine triggers. Specific medications such as triptans, ergotamines, or calcitonin gene-related peptide receptor (CGRP) antagonists may be used in those experiencing headaches that do not respond to the OTC pain medications. For people who experience four or more attacks per month, or could otherwise benefit from prevention, prophylactic medication is recommended. Commonly prescribed prophylactic medications include beta blockers like propranolol, anticonvulsants like sodium valproate, antidepressants like amitriptyline, and other off-label classes of medications. Preventive medications inhibit migraine pathophysiology through various mechanisms, such as blocking calcium and sodium channels, blocking gap junctions, and inhibiting matrix metalloproteinases, among other mechanisms. Non-pharmacological preventive therapies include nutritional supplementation, dietary interventions, sleep improvement, and aerobic exercise. In 2018, the first medication (Erenumab) of a new class of drugs specifically designed for migraine prevention called CGRPs was approved by the United States Food and Drug Administration (FDA). As of July 2023, the FDA has approved eight drugs that act on the CGRP system for use in the treatment of migraine.

Globally, approximately 15% of people are affected by migraine. In the Global Burden of Disease Study, conducted in 2010, migraine ranked as the third-most prevalent disorder in the world. It most often starts at puberty and is worst during middle age. As of 2016^[update], it is one of the most common causes of disability.

Migraine typically presents with self-limited, recurrent severe headaches associated with autonomic symptoms. About 15–30% of people living with migraine experience episodes with aura, and they also frequently experience episodes without aura. The severity of the pain, duration of the headache, and frequency of attacks are variable. A migraine attack lasting longer than 72 hours is termed status migrainosus. There are four possible phases to a migraine attack, although not all the phases are necessarily experienced:

Migraine is associated with major depression, bipolar disorder, anxiety disorders, and obsessive–compulsive disorder. These psychiatric disorders are approximately 2–5 times more common in people without aura, and 3–10 times more common in people with aura.

Prodromal or premonitory symptoms occur in about 60% of those with migraine, with an onset that can range from two hours to two days before the start of pain or the aura. These symptoms may include a wide variety of phenomena, including altered mood, irritability, depression or euphoria, fatigue, craving for certain food(s), stiff muscles (especially in the neck), constipation or diarrhea, and sensitivity to smells or noise. This may occur in those with either migraine with aura or migraine without aura. Neuroimaging indicates the limbic system and hypothalamus as the origin of prodromal symptoms in migraine.