Migraine

Most common cause of episodic headache

Aetiology

  • More common in females - 1:2.5
  • Triggers: sleep, diet, stress, hormonal, physical exertion

Pathophysiology

Migraine without aura (80%)

  • Both vascular and neural influences cause migraines in susceptible individuals
  • Stress triggers changes in the brain which cause serotonin to be released
  • Blood vessels constrict and dilate
  • Chemicals including substance P irritate nerves and blood vessels causing pain

Migraine with aura (20%)

  1. Cortical spreading depolarisation in the migraine centre of the brain (dorsal raphe nucleus, locus coeruleus)
  1. Activation of the trigeminal vascular system causes dilation of blood vessels
  1. Release of substance P, neurokinin A, CGRP

→ Increased sensitivity

  • In both cases, the chemicals result in the sensitization of trigeminal neurones and brainstem pain pathways
  • This makes otherwise innocuous sensory stimuli (such as CSF pulsation and head movement) painful, and light and sound are perceived as uncomfortable

Clinical presentation

  • Classically, a unilateral throbbing headache preceded by an aura, such as visual (eg. lines, zigzags) or sensory (paraesthesia spreading from fingers to face) symptoms
  • The headache may last 4-72 hours and is associated with photophobia and phonophobia
  • There may be identifiable triggers such as oral contraceptives or chocolate.

Migraine without aura - IHS critera

  • At least 5 attacks
  • 4-72 hours
  • 2 of: moderate/severe, unilateral, throbbing pain, worst movement
  • 1 of: autonomic features, photophobia/phonophobia

Migraine with aura

  • Aura fully reversible visual, sensory, motor or language symptom
  • Aura duration 20-60 mins
  • Headache follows < 1 hour later but aura can occur simultaneously
  • Visual aura most common, positive symptoms usually monochromatic

'Atypical' migrane

  • Acephalgic - no headache
  • Basilar - very nauseating, vertigo
  • Retinal, opthalmic
  • Hemiplegic (familial/sporadic)
  • Abdominal - more common in young children

Investigations

  • Headache diary may help identify triggers

Management

Non-pharmacological

  • Set realistic goals
  • Education - avoid triggers
  • Headache diary
  • Relaxation/stress management

Pharmacological

Acute
  • NSAID (aspirin, naproxen, ibuprofen) taken as early as possible
  • If gastroparesis consider antiemetic
  • Triptans (5HT agonist) e.g. rizatriptan, eletriptan, sumatriptan - take at start of headache
Prophylaxis
  • Consider if patient is experiencing more than 3 attacks per month or very severe attacks
  • Drugs used include amitriptyline, propranalol (CI: asthma), topiramate (CI: woman of childbearing age)
  • Also consider non-pharmacological methods: acupuncture, relaxation exercises