Migraine

Migraine – Comprehensive Study Guide for Medical Students

Definition

Migraine is a recurrent primary headache disorder characterized by moderate to severe, often unilateral, pulsatile head pain lasting 4–72 hours, frequently associated with nausea, vomiting, photophobia, and phonophobia. Attacks may be preceded or accompanied by transient focal neurological symptoms known as aura. The ICHD-3 classifies migraine into several subtypes, most commonly migraine without aura and migraine with aura.

Epidemiology

Migraine is one of the most common and disabling neurological disorders worldwide, with a lifetime prevalence of approximately 12–15% in the general population and a marked female predominance (roughly 3:1 after puberty). It commonly begins in adolescence or early adulthood and is a leading cause of years lived with disability in young and middle-aged adults. School- and college-based studies show a substantial burden in children, adolescents, and young adults, with high rates of absenteeism, reduced academic performance, and frequent use of acute medications, often without structured medical follow-up.^[1][2]

Pathophysiology

Migraine is a complex brain network disorder involving genetic susceptibility, abnormal sensory processing, and dysregulation of pain-modulating pathways. The historical vascular theory (intracranial vasoconstriction followed by vasodilation) has been largely replaced by a neurovascular model that integrates neuronal and vascular mechanisms.

Key elements include:

• Cortical spreading depression (CSD): A slowly propagating wave of neuronal depolarization followed by suppression of cortical activity, believed to underlie migraine aura. CSD activates trigeminovascular afferents and can promote neurogenic inflammation.
• Trigeminovascular system activation: Nociceptive fibers from the trigeminal ganglion innervate intracranial vessels and meninges. Their activation leads to the release of vasoactive neuropeptides such as calcitonin gene-related peptide (CGRP), substance P, and neurokinin A, producing vasodilation, plasma protein extravasation, and peripheral sensitization.
• CGRP and other neuropeptides: CGRP is a key mediator in migraine pathophysiology, promoting vasodilation and transmission of nociceptive signals in the trigeminal system. Its central role is supported by the efficacy of CGRP antagonists and monoclonal antibodies in migraine prevention and acute treatment.^[3]
• Central sensitization: Repeated or sustained nociceptive input from meningeal afferents produces sensitization in second-order neurons in the trigeminal nucleus caudalis and higher centers. Clinically, this manifests as cutaneous allodynia and heightened sensitivity to sensory stimuli.
• Brainstem and hypothalamic dysfunction: Imaging studies show activation of the dorsal pons, locus coeruleus, and hypothalamus during attacks. These structures regulate pain modulation, arousal, autonomic function, and circadian rhythms, which explains prodromal symptoms (yawning, mood changes, food cravings) and the relationship with sleep and hormonal triggers.
• Genetic and environmental factors: Migraine is polygenic with complex inheritance. Environmental triggers (stress, sleep disturbance, certain foods, hormonal fluctuations, sensory overload) interact with this genetic predisposition to lower the threshold for attacks.

Clinical Presentation

Typical Migraine Attack Phases

• Prodrome (hours to days before pain): Subtle symptoms such as fatigue, yawning, mood changes (irritability or euphoria), neck stiffness, food cravings, and increased urination. These reflect hypothalamic and brainstem involvement.
• Aura (in ~25–30% of patients): Fully reversible focal neurological symptoms that usually develop over 5–20 minutes and last <60 minutes. Most are visual (flashing lights, scotoma, zigzag lines, fortification spectra), but sensory (tingling, numbness), language (dysphasia), or motor (in hemiplegic migraine) auras can occur.
• Headache phase: Moderate to severe, throbbing or pulsatile pain, typically unilateral but may be bilateral. Attacks last 4–72 hours if untreated. Pain worsens with routine physical activity and is accompanied by nausea, vomiting, photophobia, and phonophobia. Patients often seek a dark, quiet room.
• Postdrome: After pain resolution, patients may experience fatigue, cognitive slowing (“migraine hangover”), residual neck discomfort, and mild head sensitivity.

Key Diagnostic Features (Migraine Without Aura)

According to ICHD-3, migraine without aura is characterized by:

• At least 5 attacks fulfilling the criteria.
• Headache attacks lasting 4–72 hours (untreated or unsuccessfully treated).
• Headache has at least two of the following: unilateral location, pulsating quality, moderate or severe intensity, aggravation by or causing avoidance of routine physical activity.
• During headache, at least one of the following: nausea and/or vomiting, photophobia and phonophobia.
• Not better accounted for by another ICHD-3 diagnosis.

Red Flags and Atypical Features

While most migraines are benign, always screen for features suggesting secondary headache:

• Sudden, thunderclap onset (maximal at onset).
• New or markedly different headache in patients >50 years or with systemic illness.
• Progressive worsening, change in pattern or frequency.
• Focal neurological deficits persisting beyond typical aura duration.
• Fever, meningismus, altered mental status, seizure, or immunosuppression.

Diagnosis

Migraine is a clinical diagnosis based on history and physical examination. No specific laboratory or imaging test confirms migraine, but investigations are indicated when there are atypical features or red flags.

History Taking

• Characterize the headache: Onset, duration, location, quality (throbbing vs pressure), intensity, aggravating/relieving factors, associated symptoms (nausea, vomiting, photophobia, phonophobia, aura).
• Attack frequency and disability: Days with headache per month, days with migraine per month, impact on daily functioning, school or work absenteeism.
• Triggers: Sleep disturbance, stress, hormonal changes, fasting, specific foods, sensory overstimulation, weather changes.
• Family history: Often positive in first-degree relatives.
• Medication history: Use of over-the-counter analgesics, triptans, ergot derivatives, caffeine-containing combinations; screen for medication overuse headache.

Physical and Neurologic Examination

• Vital signs, general exam for systemic features.
• Full neurologic exam including funduscopy, cranial nerves, motor, sensory, coordination, and gait.
• Typically normal between attacks; any persistent deficit warrants further evaluation.

Investigations

• Neuroimaging: MRI (preferred) or CT is indicated when red flags are present, new or progressively worsening headaches occur, focal deficits are detected, or in late-onset headaches. Routine imaging in classic episodic migraine without red flags has low yield.
• Laboratory tests: Guided by clinical suspicion to evaluate secondary causes (e.g., inflammatory markers, endocrine tests).

Management

Migraine management includes acute (abortive) therapy, preventive (prophylactic) therapy, and non-pharmacologic strategies. Treatment should be individualized based on attack frequency, severity, comorbidities, and patient preference.

General Principles

• Confirm the diagnosis and educate patients about the nature of migraine and realistic treatment goals.
• Encourage early treatment of attacks when pain is mild for best response.
• Limit use of acute medications to avoid medication overuse headache (typically <10 days/month for triptans, opioids, combination analgesics and <15 days/month for simple analgesics).
• Identify triggers and comorbidities (anxiety, depression, sleep disorders) and address them as part of a comprehensive plan.

Acute (Abortive) Treatment

Goal: Rapid relief of pain and associated symptoms with restoration of function and minimal adverse effects.

First-Line for Mild to Moderate Attacks

• NSAIDs and simple analgesics: Ibuprofen, naproxen, diclofenac, or acetaminophen are effective, especially when taken early. Combination preparations with caffeine may enhance efficacy but carry risk of overuse.
• Antiemetics: Metoclopramide or prochlorperazine can be added for prominent nausea/vomiting and may improve gastric motility and absorption of oral agents.

First-Line for Moderate to Severe Attacks or Failure of NSAIDs

• Triptans (5-HT1B/1D agonists): Sumatriptan, rizatriptan, zolmitriptan, eletriptan, and others are standard acute treatments. They inhibit trigeminovascular neurotransmission and cause cranial vasoconstriction. They are most effective when taken early in the attack.
• Contraindications: Known coronary artery disease, cerebrovascular disease, uncontrolled hypertension, or hemiplegic/basilar-type migraine.

Emerging and Innovative Acute Therapies

• Gepants: Small-molecule CGRP receptor antagonists used for acute treatment; beneficial in patients with cardiovascular contraindications to triptans and in those who do not respond to or tolerate triptans.^[3]
• Lasmiditan: 5-HT1F receptor agonist that is non-vasoconstrictive; suitable for patients with vascular risk but associated with central nervous system adverse effects like dizziness and somnolence.

Preventive (Prophylactic) Treatment

Indications for preventive therapy include frequent attacks (commonly ≥4 migraine days/month), significant disability, prolonged or atypical aura, failure or contraindication to acute therapies, or patient preference to reduce attack frequency and intensity.

Traditional Preventive Agents

• Beta-blockers: Propranolol, metoprolol, and timolol are effective first-line options, especially in patients with coexisting hypertension or anxiety.
• Antiepileptic drugs: Topiramate and valproate have robust evidence; topiramate is especially widely used. Side-effect profiles (cognitive slowing, paresthesias, weight changes, teratogenicity) must be considered.
• Tricyclic antidepressants: Amitriptyline is helpful, particularly in patients with comorbid depression, anxiety, or insomnia, but can be sedating and anticholinergic.
• Calcium channel blockers: Verapamil may be helpful, particularly in some aura phenotypes, although evidence is less robust than for beta-blockers or antiepileptics.

Innovative and Targeted Preventive Therapies

• CGRP monoclonal antibodies: Erenumab, fremanezumab, galcanezumab, and eptinezumab are injectable monoclonal antibodies that target CGRP or its receptor and significantly reduce monthly migraine days with favorable tolerability profiles. They are particularly useful in episodic and chronic migraine refractory to traditional preventives.^[3]
• Oral gepants for prevention: Some CGRP antagonists are used in a preventive fashion (e.g., taken daily or every other day), representing an oral alternative to injectable monoclonal antibodies.
• OnabotulinumtoxinA: Indicated for chronic migraine (≥15 headache days per month, of which ≥8 are migraine days). It is administered as per standardized injection protocols across head and neck muscle groups and can reduce attack frequency and disability.

Melatonin and Other Adjunctive Preventive Options

• Melatonin: Melatonin, a regulator of circadian rhythm with anti-inflammatory and antinociceptive properties, has shown efficacy and good safety as a prophylactic agent in some randomized controlled trials. It may be particularly useful when sleep disturbance is a prominent comorbidity, though it is generally considered adjunctive or second-line compared with standard preventives.^[4]
• Other supplements: Some evidence supports riboflavin, magnesium, and coenzyme Q10, but data are less robust and dosing regimens vary.

Non-Pharmacologic Management

• Lifestyle modification: Regular sleep, meals, hydration, exercise, and stress management help stabilize migraine threshold. Avoiding excessive caffeine and alcohol and managing work–rest balance is beneficial.
• Trigger management: Encourage patients to maintain a headache diary to identify and, when feasible, avoid individual triggers (e.g., specific foods, bright light, strong odors). Note that strict avoidance of all triggers is not always necessary or realistic.
• Behavioral therapies: Cognitive-behavioral therapy, biofeedback, and relaxation training have evidence for reducing migraine frequency and improving coping strategies.
• Sleep-focused interventions: In chronic migraine with coexisting insomnia, structured sleep psychoeducation and hygiene interventions can improve sleep quality and migraine metrics.^[5]
• Physical therapy: For patients with prominent neck pain or cervicogenic contribution, cervical physical therapy may reduce pain sensitivity and improve disability when integrated with medical care.^[6]

Special Considerations

Pediatric and Adolescent Migraine

• Common and often under-recognized in school-age children and adolescents, with significant impact on academic performance and quality of life.^[1]
• Headache may be bilateral and shorter in duration than in adults; associated gastrointestinal symptoms (abdominal migraine, cyclic vomiting) are more frequent.
• Non-pharmacologic measures and careful attention to school stresses, sleep, and family dynamics are key. Use age-appropriate dosing and agents with good safety profiles.

Chronic Migraine

• Defined as headache occurring on ≥15 days per month for >3 months, with ≥8 days meeting criteria for migraine.
• Often associated with medication overuse, psychiatric comorbidities, and sleep disorders.
• Management focuses on withdrawing overused medications, initiating effective preventive therapy (e.g., topiramate, CGRP mAbs, onabotulinumtoxinA), and addressing comorbidities.

Key Clinical Pearls for Medical Students

• Migraine is clinical: Diagnosis is based on a careful history; imaging is reserved for atypical or red-flag presentations.
• Ask about disability: Frequency alone does not capture disease burden; use tools like MIDAS or HIT-6 where available.
• Beware of medication overuse headache: Overuse of acute medications can maintain or worsen headache frequency; always review analgesic use.
• Aura vs TIA: Aura typically spreads gradually over minutes, with positive symptoms (flashes, tingling) followed by negative symptoms; TIAs are often sudden and negative (loss of function).
• Triptan timing matters: They work best when taken early in the attack, but not during the aura phase alone.
• Match preventive to comorbidity: Beta-blockers in patients with hypertension or anxiety; amitriptyline in those with insomnia or depression; topiramate in overweight patients (with caution for cognitive effects).
• CGRP pathway therapies: Represent a major advance for patients with refractory episodic and chronic migraine and illustrate the central role of CGRP in pathophysiology.^[3]
• Address sleep: Poor sleep is both a trigger and perpetuating factor; simple sleep psychoeducation can be impactful, especially in chronic migraine.^[5]
• Pediatric perspective: High prevalence in school populations; always ask about headache in children with concentration or performance issues.^[1]

Summary

Migraine is a highly prevalent, disabling primary headache disorder driven by complex interactions between cortical, brainstem, and trigeminovascular networks. Diagnosis is clinical, grounded in ICHD-3 criteria and a careful headache history. Management combines acute and preventive pharmacologic strategies with lifestyle, behavioral, and sleep-focused interventions. Emerging targeted therapies such as CGRP monoclonal antibodies, gepants, and other innovative treatments are reshaping care, particularly for individuals with refractory or chronic migraine. A structured, patient-centered approach can dramatically reduce attack burden and improve quality of life.