MD Notes

creation date: 2026-06-11 15:38
tags: Pathologies

Migraine

Background

Definitions

Migraine is an episodic disorder characterized by a severe headache, amongst other symptoms.

Migraines affect 12-15% of the population, with a 3:1 ratio for females to males.

Pathophysiology

Former theory (no longer viable) suggested:

  • Vasodilation caused headache
  • Vasoconstriction caused aura

Current evidence suggests a primary neuronal dysfunction.

  1. Cortical spreading depression (wave of depolarization across cerebral cortex) causing aura, trigeminal nerve afferents, alteration of blood-brain barrier permeability
  2. Activation of the trigeminovascular system results in release of vasoactive neuropeptides causing neurogenic inflammation; prolongs and intensifies pain
  3. Sensitization leading to lowering threshold of pain response; allows for exacerbation and throbbing quality

Migraine is also associated with:

  • Serotonin activation
  • Calcitonin gene-related peptide expression
  • Right-to-left cardiac shunt (eg. PFO, ASD)

Migraines also have a strong inherited basis. Risk of migraines is 3 times greater if relatives have migraines. The exact pattern of inheritance is unknown.

Clinical Presentation

Signs & Symptoms

Migraines occur recurrently. Each episode occurs over the course of hours to days. A typical attack progresses through four phases:

Prodrome
24-48 hours prior to onset of a headache:

  • Light/sound sensitivity
  • Fatigue
  • Neck pain
  • Cognitive symptoms (irritability or euphoria)
  • Food cravings, yawning, changes to bowel function

Aura
In 25% of patients, a migraine aura manifests just preceding or at the start of the headache as one or more focal neurologic symptoms:

  • Positive symptoms
    • Visual (bright lines, shapes, objects)
    • Auditory (tinnitus, noises, music)
    • Motor (jerking, repetitive rhythmic movement)
  • Negative symptoms
    • Loss of vision (small area of loss lateral to point of fixation)
    • Sensory loss (tingling in a limb or side of face)
    • Language aura (mild wording difficulties to dysphasia)

Headache
Migraine headaches are described as:

  • Mostly unilateral
  • Throbbing or pulsatile quality
  • Severity increase over hours
  • Worsen by physical activity or exercise

Associated symptoms include:

  • Photophobia/phonophobia
  • Nausea and vomiting
  • Cutaneous allodynia

Postdrome
Following resolution of throbbing quality, postdrome includes:

  • Transient pain with sudden head movement
  • Exhaustion, feeling of being drained
  • Mild elation or euphoria

Precipitating & Exacerbating Factors

In order of descending frequency reported:

  • Emotional stress
  • Hormones in females
  • Not eating
  • Weather
  • Sleep disturbances
  • Odours
  • Neck pain
  • Lights
  • Alcohol
  • Smoke
  • Sleeping late
  • Heat
  • Food
  • Exercise
  • Sexual activity

Migraine Subtypes

Although specific subtypes are not proven to exist (likely unrelated to the migraine), several subtypes have been characterized.

  • Migraine with brainstem aura - aura includes vertigo, dysarthria, tinnitus, diplopia, ataxia, decreased LOC, hypacusis
  • Hemiplegic migraine - aura with unilateral motor weakness; scintillating scotoma, visual field defect, numbness, paresthesia, aphasia, fever, lethargy, coma, seizures during headache
  • Retinal migraine - repeated attacks of monocular scotomata or blindness lasting less than an hour
  • Chronic migraine - 15 or more days a month for >3 months
  • Vestibular migraine - episodic vertigo with association to migraines
  • Estrogen-associated migraine - migraines with close temporal relationship to onset of menses
  • Complications of migraine
    • Status migrainosus (attack >72 hours)
    • Persistent aura without infarct (aura >1 week with no infarct on neuroimaging)
    • Migrainous infarction (migraine with persistent aura and infarct on imaging)
    • Migraine aura-triggered seizure

History & Physical Exam

Diagnosis

Criteria

Diagnosis is made clinically. The International Classification of Headache Disorders, 3rd edition (ICHD-3) has criteria for migraine without and with aura.

Migraine without aura

  1. At least five attacks fulfilling criteria 2-4
  2. Headache attacks last 4-72 hours (untreated or unsuccessfully treated)
  3. Headache has at least two of the following characteristics:
    • Unilateral location
    • Pulsating quality
    • Moderate or severe pain intensity
    • Aggravation by or causing avoidance of routine physical activity
  4. During headache, at least one of the following:
    • Nausea and/or vomiting
    • Photophobia and phonophobia
  5. No better alternative diagnosis

Migraine with aura

  1. At least two attacks fulfilling criteria 2-3
  2. One or more of the following fully reversible aura symptoms:
    • Visual
    • Sensory
    • Speech and/or language
    • Motor
    • Brainstem
    • Retinal
  3. At least three of the following six characteristics:
    • At least one aura symptom spreads gradually over ≥5 minutes
    • Two or more symptoms occur in succession
    • Each individual aura symptom lasts 5-60 minutes
    • At least one aura symptom is unilateral
    • At least one aura symptom is positive
    • The aura is accompanied or followed within 60 minutes, by headache
  4. No better alternative diagnosis

Work-up

Classic presentation typically does not require further workup. It should be noted that it is unlikely for someone with no history of migraines to present with one later in life, which should prompt further evaluation.

Differential

Alternative diagnoses are discussed separately.

Red Flags / Complications

Findings that should prompt neuroimaging include:

  • Unexplained abnormal finding on neurologic exam (eg. new fixed weakness or vision loss)
  • Atypical headache features (eg. abrupt onset, postural headache)
  • Headachese that do not fulfill the definition of migraine or other primary headache disorder
  • Additional risk factors for secondary headache (eg. onset after age 50, pregnancy, immune deficiency)

Management

Acute Treatment

A variety of medications can be used for symptomatic relief. The best strategy will need to be individualized.

A step-wise approach is prescribed for patients to self-administer during episodes:

  1. NSAIDs/acetaminophen
  2. Triptan with or without NSAIDs
  3. CGRP inhibitors

A number of options exist beyond these three. Patients who are refractory with the above options may wish to consider less commonly used options.

Patients should be counselled on the risk of medication overuse headache. Risk from triptans are intermediate. NSAIDs have low risk, and CGRP inhibitors are not associated with MOH.

Emergency department
Patients presenting to the ED typically have exhausted their usual treatment. Injectable/IV options of the above are an option, however, most EDs utilize a “migraine cocktail”.

  • Metoclopramide, ketorolac, normal saline

Prevention

Indications for preventative migraine treatment:

  • Frequent (approximately ≥4 headache days per month) or long-lasting migraine attacks
  • Migraine attacks that cause significant disability or diminished quality of life despite appropriate acute treatment
  • Contraindication to acute therapies
  • Failure of acute therapies
  • Serious adverse effects of acute therapies
  • Risk of medication overuse headache

First line options are:

  • Emitriptyline
  • Venlafaxine
  • Metoprolol or propranolol
  • Topiramate
  • CGRP inhibitor

References

Tools / Guidelines

Additional Reading

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