Lecture 21: Migraine Flashcards
What is the definition of a migraine?
leading cause of disability worldwide, particularly in those under 50
primarily headache disorder characterized by recurring headaches that are moderate to severe, pulsating in nature, last from 2-72 hours
sensitivity to normal sensory input (light, sound, head movement)
sometimes nausea and vomiting
What is migraine aura?
migraine sometimes (~20%) preceded with aura (visual disturbances consisting of flashing lights or zigzag lines moving across the field of vision)
thought to be driven by cortical spreading depression: wave of neuronal depolarization followed by desensitization (“depression”) that propagates across the cortex
What is migraine epidemiology?
migraine risk a mix of genetic and environmental factors
affects women more than men
increase incidence in women after puberty (hormones?)
some genetic contribution: familial hemiplegic migraines
What is familial hemiplegic migraine?
migraine that includes weakness of half of the body
autosomal dominant inheritance
3 known genetic mutations associated with FHM: P/Q-type calcium channel, Na+/K+ATPase, Na+ channel subunit
mutations lower the threshold for cortical spreading depression
What is the trigeminal system?
trigeminal nerve is the largest cranial nerve
peripheral processes divided into three branches - ophthalmic, maxillary, and mandibular
What are the three purposes of the trigeminal system?
senses pain and temperature in the head region
innervates the dura mater (membrane that surrounds the brain)
controls cerebral blood vessels (trigeminovascular system)
What is the mechanism of migraine?
pain in head detected by ophthalmic branch of the trigeminal nerve innervating dura mater and associated blood vessels
cause of migraine still unknown, but thought to be a neurovascular disease
- extracerebral vessels dilate during migraine attack
- cranial blood vessel stimulation provokes headache
- vasoconstrictor drugs alleviate pain
What is the relationship between serotonin and migraine?
release of 5-HT leads to vasoconstriction
low 5-HT levels in migraineurs between attacks
5-HT is released during migraine attacks
What is the relationship between CGRP and migraine?
calcitonin gene-related peptide (CGRP) located in trigeminal peripheral afferents
released from afferents in response to pain, leads to vasodilation
CGRP elevated in those with migraines
What are the two treatment strategies for migraines?
treatment strategies incorporates both prophylactic and abortive strategies
prophylactic treatments are taken daily to prevent attacks, abortive treatments taken once an attack occurs
What are non-pharmacological prophylactic interventions?
identify triggers (diet, exercise, consistent sleep, avoiding excessive caffeine and alcohol, minimize stress)
What are pharmacological prophylactic interventions?
beta blockers (propanolol), anticonvulsants (gabapentin), antidepressants (amitriptyline)
What are abortive treatment strategies?
non-specific analgesics (asprin, acetaminophen, NSAID, opioids)
risk of medication overuse headache
What is the relationship between caffeine and migraine?
caffeine is an adenosine receptor antagonist
leads to vasoconstriction
increases absorption of some analgesics (acetaminophen, ergotamines)
improves migraine treatment during attack
but may also trigger headaches or result in rebound headache (withdrawal)
What are ergotamines?
ergot alkaloid (like LSD)
first specific anti-migraine agents (introduced in 1926), but no longer first line therapy
agonists for 5HT-1b/d receptors that inhibit neurogenic inflammation
but, low degree of receptor selectivity which increases the risk of experiencing a drug-induced side effect
