12.2 Migraine Headaches and Migraine Headache Drugs

Pathophysiology and Symptoms of Migraine Headaches

Migraines are more than bad headaches. They're complex neurological events involving the trigeminovascular system, and they unfold in distinct phases. Understanding the underlying mechanisms helps you anticipate symptoms, choose the right drug class, and educate patients effectively.

Mechanisms of migraine headaches

The trigeminovascular system is central to migraine pathophysiology. The trigeminal nerve innervates the meninges and cerebral blood vessels. When activated, it releases vasoactive peptides, primarily CGRP (calcitonin gene-related peptide) and substance P, which cause vasodilation and neurogenic inflammation around cranial blood vessels. This inflammation is what drives the throbbing pain.

Two other mechanisms contribute:

• Cortical spreading depression (CSD): A slow wave of neuronal and glial depolarization spreads across the cortex, followed by a period of suppressed neural activity. CSD is responsible for aura symptoms and also activates the trigeminal nerve, linking aura to the headache phase.
• Serotonergic dysfunction: An imbalance in serotonin (5-HT) levels increases pain sensitivity and promotes vasodilation. This is why so many migraine drugs target serotonin receptors.

Triggers and symptoms of migraines

Common triggers include:

• Stress and anxiety
• Hormonal changes (menstrual cycle, menopause, oral contraceptive use)
• Sleep disturbances (both insomnia and oversleeping)
• Dietary factors (alcohol, caffeine withdrawal, aged cheeses, processed meats)
• Environmental factors (bright lights, loud noises, strong odors)

Migraines progress through four phases, though not every patient experiences all of them:

1. Prodrome (hours to days before headache): Fatigue, mood changes, food cravings, neck stiffness. Patients who learn to recognize prodrome symptoms can treat earlier and more effectively.
2. Aura (occurs in roughly 25-30% of migraine patients, usually before the headache): Visual disturbances (flashing lights, blind spots), sensory changes (tingling, numbness), or language difficulties (trouble finding words). Aura typically lasts 20-60 minutes.
3. Headache phase: Unilateral, pulsating pain of moderate to severe intensity, worsened by physical activity. Often accompanied by nausea, vomiting, photophobia (light sensitivity), and phonophobia (sound sensitivity).
4. Postdrome (after headache resolves): Fatigue, cognitive difficulties ("brain fog"), mood changes. Patients sometimes describe feeling "washed out" for hours to a day.

Pharmacological Management of Migraine Headaches

Migraine treatment falls into two categories: preventive therapy (taken daily to reduce attack frequency and severity) and acute/abortive therapy (taken at the onset of a migraine to stop it). Knowing which drugs belong to which category, and how they work, is essential for safe administration.

Classes of migraine medications

Preventive medications (prophylaxis) are taken on a regular schedule, regardless of symptoms:

• Beta-blockers (propranolol, metoprolol)
• Antidepressants (amitriptyline, venlafaxine)
• Anticonvulsants (topiramate, valproic acid)
• CGRP monoclonal antibodies (erenumab, fremanezumab): These are newer agents that block the CGRP pathway directly. They're given as monthly or quarterly injections and tend to have fewer systemic side effects than older preventive options.

Acute treatment medications (abortive therapy) are taken at the onset of a migraine:

• Triptans (sumatriptan, rizatriptan): First-line for moderate to severe migraines
• Ergotamines (ergotamine, dihydroergotamine): Older agents, used less frequently now
• NSAIDs (ibuprofen, naproxen): Often effective for mild to moderate migraines
• Combination analgesics (acetaminophen/aspirin/caffeine): Available OTC; caffeine enhances analgesic absorption

Pharmacology of triptans vs. ergotamines

These two drug classes both target serotonin receptors, but they differ in selectivity, side effect profiles, and clinical use.

Triptans are selective serotonin receptor agonists, primarily targeting 5-HT1B and 5-HT1D receptors. Their mechanism involves three actions:

1. Vasoconstriction of dilated cranial blood vessels (5-HT1B)
2. Inhibition of vasoactive peptide release, including CGRP and substance P (5-HT1D)
3. Reduction of neurogenic inflammation and pain transmission

Triptans are generally preferred over ergotamines because of their selectivity and more predictable side effect profile.

Ergotamines are nonselective serotonin receptor agonists with affinity for 5-HT1B, 5-HT1D, and 5-HT1F receptors, plus dopamine and adrenergic receptors. They produce similar effects (vasoconstriction, trigeminal nerve inhibition, reduced inflammation), but their lack of selectivity means more side effects. Dihydroergotamine (DHE) is sometimes used for prolonged or refractory migraines, often given IV or intranasally.

Side effects of migraine drugs

The chest tightness seen with triptans is usually benign (a sensation, not cardiac ischemia), but it must be evaluated in patients with cardiovascular risk factors. This is why cardiovascular disease is a hard contraindication.

Nursing considerations for migraine treatment

Assessment:

• Obtain a thorough headache history: triggers, frequency, severity, duration, and what treatments the patient has already tried
• Screen for contraindications and potential drug interactions before administering any migraine medication
• Ask about pregnancy status, especially before giving ergotamines or valproic acid

Administration:

• Ensure proper dosing and route for each medication. Triptans come in oral, nasal spray, and injectable forms; route selection depends on symptom severity and whether the patient is vomiting.
• Educate patients that acute medications work best when taken early, at the first sign of a migraine, not after the pain is fully established.

Monitoring:

• Assess treatment effectiveness: Has pain decreased? Have associated symptoms (nausea, photophobia) improved?
• Monitor vital signs, particularly blood pressure and heart rate, in patients taking ergotamines, triptans, or beta-blockers
• Watch for signs of medication overuse headache (rebound headache) in patients using acute treatments more than 2-3 days per week

Patient education:

• Teach patients to avoid known triggers and maintain consistent routines (sleep, meals, hydration)
• Stress that preventive medications must be taken daily as prescribed, even when feeling well; they take weeks to reach full effectiveness
• Warn against exceeding recommended doses of acute medications, as overuse can paradoxically worsen headache frequency

Patient education for migraine management

Lifestyle modifications:

• Stress management (relaxation techniques, regular exercise, meditation)
• Consistent sleep schedule: both too little and too much sleep can trigger migraines
• Avoidance of known dietary triggers (alcohol, caffeine in excess, aged cheeses)
• Adequate hydration and regular meals; skipping meals is a common trigger

Medication use:

• Take preventive medications on schedule, even during headache-free periods
• Use acute medications at migraine onset; don't wait for pain to peak
• Do not exceed recommended dosing. Using acute medications (especially triptans, ergotamines, or combination analgesics) more than 10-15 days per month can cause medication overuse headache

Tracking and follow-up:

• Keep a headache diary recording triggers, symptoms, timing, and response to medications. This is one of the most useful tools for optimizing treatment.
• Share the diary with healthcare providers at follow-up visits
• Report any adverse effects or changes in migraine patterns promptly
• Schedule regular check-ups to evaluate whether the current treatment plan is working

Support resources:

• The American Migraine Foundation and National Headache Foundation offer reliable patient education materials
• Support groups or counseling can help patients cope with the impact of chronic migraines on daily functioning