Migraine and Emesis Flashcards
What is a migraine? (14:42)
- Painful, pulsing headache typically lasting 4 hours to 3 days
- Often unilateral, associated with photophobia
- 7% of men and 17% of women experience at least one migraine a year
- Prevalence peaks in middle age
Describe the incidence of migraine.
- Episodic
- 10 to 15% of population
- Female:Male ratio 3.5:1
- Affects 16% of menstruating females
- 2-3 times more common if first degree relative has it
What is the cost of migraine?
- 100,000 absent from work or school as a result every day
- Costing UK economy £1.5 billion per annum
- No effect on life expectancy
Describe the symptomology of migraine.
Up to five stages:
Prodrome:
- Yawning, mood or appetite change (warning phase, occurs in 60%)
1) Aura (Classical Migraine):
- Initial visual disturbance, 30 minutes
- Visual area lost, surrounding area ‘shimmers’
- 15% of sufferers = Classical Migraine (w/aura) + Unilateral…
2) Unilateral throbbing headache (Common Migraine):
- Lasting 4 to 72 hours
- Photophobia
- N&V
- Prostrate; to lie down
- 85% of sufferers = Common Migraine, going straight into this phase (no aura)
Resolution:
- Deep sleep and loss of headache
Recovery:
- Often get exhausation
What are the genetic risks of migraine? What are the mutations?
Familial hemiplegic migraine; w/aura:
- Rare autosomal disorder
- 50% of cases; point mutations in CACNA1A gene; encodes pore-forming α1A subunit of the P/Q voltage-gated calcium channel (chromosome 19)
- Mutations result in an altered channel conductance and density of expression in vitro in cell lines
- 30% of cases; mutations in the ATP1A2 gene that encodes the Na+k+ pump α2 subunit
What mutation is associated with Common Migraine?
- Mutation in the TRESK K2P potassium channel in spinal neurones
- Common Migraine; w/o aura (85%)
What is the pathophysiology of migraines WRT it being of vascular origin (now disproven)?
Was thought to be as a result of abnormal cerebral blood flow:
- Intracerebral vasoconstriction was thought to cause the aura (Classical Migraine)
- Extracerebral vasodilation (particularly in dura mater)
»> Resulting in pain
• However, blood flow changes do not occur in Common Migraine (sans aura)
• MRI cerebral blood flow analysis confirmed biphasic changes, but wrong pattern.
»> Headache started in vasoconstriction
Explain the pathophysiology of migraines WRT the cortical spreading depression theory; neuronal origin (kinda right/kinda disproven)
- Blood flow change does not correspond to intracranial artery distribution
- Vasoconstriction spreads from posterior of one hemisphere = neural mediation (depression of cortical neurones in animals)
- May be cause of aura, but not migraine.
- Changes in blood flow driven by change in metabolic demand resulting from neuronal depression are thought to result in progressive change in MR signal in occipital cortex
- Aura usually involves wave of electrical activity starting in the occipital cortex, spreading slowly at 2-3 mm/min associated w/visual hallucinations across the visual field, that are reproducible in the same individual
- Therapy that prevents the aura can still leave the headache
Explain the pathophysiology of migraines WRT the current theory; sensory nerve activation is the cause. What is released/responsible?
Migraine = enhanced trigeminovascular neuron activity
- Trigeminal nerve innervates frontal and parietal cortex, as well as meninges vascular bed
Trigeminal nerve is bipolar in nature:
• Dorsal horn spinal cord; pain
• Cranial blood vessel & meninges; vasodilation + inflammation (powerful mediator)
> > > Neurones contain CGRP (calcitonin gene related neuropeptide); potent vasodilator and plasma CGRP increases in migraine.
What is the trigeminal nerve responsible for innervating?
Three divisions innervating the forehead and eye:
- Ophthalmic V1 (goes up to meninges; most suspect)
- Maxillary V2 (cheek)
- Mandibular V3 (face and jaw)
These nerves:
• Sense facial touch, pain and temperature
• Control muscles used for chewing
How is migraine diagnosed?
- No definitive test/diagnosis
- Careful assessment of patient history
- Elimination of alternative causes of headache e.g. trauma, other drug treatments, rare disorders.
What is the diagnostic criteria for Common Migraine (without aura)?
International Classification of Headache Disorders, 2nd Edition (ICHD-II):
A:
- At least 5 attacks fulfilling criteria B-D (in one year)
B:
- Headache attacks lasting 4-72 hours
(untreated or unsuccessfully treated)
C:
Headache has AT LEAST 2 two of the following:
- Unilateral location
- Pulsating quality (i.e. varying with the heartbeat)
- Moderate or severe pain intensity
- Aggravation by or causing avoidance of routine physical activity (e.g. walking/climbing stairs)
D:
During headache, at least one of the following:
- Nausea and/or vomiting
- Photophobia and phonophobia
E:
Not attributed to another disorder:
- History and examination do not suggest a secondary headache disorder; or if they do, is ruled out by appropriate investigations or headache attacks do not occur for the first time in close temporal relation to the other disorder
How may migraine in children present differently to the Common/Classic Migraine?
- Attacks may be shorter-lasting (not 4-72 hours)
- Headache is more commonly bilateral
- GI disturbance more prominent (often no N&V)
Why are Migraine Diaries potentially helpful?
- Help doctors make a firm diagnosis
- Recognise warning signs of an attack
- Identify triggers
- Assessing whether acute or preventative medication is working
What may Migraine Diaries include information on, that would be clinically helpful?
- When the pain begins and frequency
- Symptoms (e.g. nausea or vision aura)
- Length of attacks
- Pain location and whether throbbing, piercing
Extra:
• Diet, medication, vitamins/health products, exercise, sleep duration
• Women; menstrual cycle details
