Migraine Headaches

Migraine Headaches Jim Ducharme MD CM FRCP Professor, Emergency Medicine Dalhousie University

A 34 year-old woman arrives with 24 hours of pulsating frontal headache. She has vomited twice, and wants the lights off. What questions do you want answered?

Previous headache history • Onset of headache • Analgesic use • Any identified trigger • Allergies/Medication intolerance

Risk factors suggesting a serious underlying cause of headache • First or worst headache, especially if abrupt onset • Change in pattern of normal headaches • New progressive persistent headache CMAJ 1997

Risk factors suggesting a serious underlying cause of headache • Headache brought on by Valsalva • Accompanying systemic symptoms: • myalgia, fever, malaise, weight loss, jaw claudication, tender scalp • Focal neurological signs or symptoms • Altered mental status CMAJ 1997

How do you decide this is a migraine and does it matter?

I.H.S. Diagnostic Criteria • Migraine without aura • > 5 episodes • Duration 4-72 hours • 2/4 of: increase with activity, moderate to severe intensity, pulsatile at some point, visual complaints • 1 of 2 of: photo/phonophobia, nausea/vomiting • Normal exam

Her physical exam is normal other than her obvious pain. You would like to treat her headache. What therapeutic endpoints do you establish before starting: • complete headache abolition? • reduction of her headache to a mild level? • avoidance of significant adverse effects? • avoidance of headache recurrence?

Pathophysiology • Aura • Spreading cortical depression, not ischemia • Brainstem • Migraine “generator” in dorsal raphe, locus ceruleus and periaqueductal gray matter • PET scans show increased blood flow, even after cessation of headache

Pathophysiology • Genetic predisposition • Deficient habituation during repetitive stimulation • Allows for surpassing or modification of threshold for migraine • External: prophylaxis, psychosocial • Internal: estrogen, stress response, foods

Pathophysiology • Threshold surpassed: • Brainstem “generator” liberates CGRP • Activation of trigeminovascular system • CGRP also elevated with pulsating chronic tension-type headaches

Pathophysiology • Nitric oxide • Vasodilator • Promotes central sensitization of trigeminal nociceptors • Sumatriptan decreases NO release in addition to inhibiting CGRP release

Pathophysiology • Trigeminal Stimulation • Ca channel activation: substance P release • Feedback to DRG: NMDA & AMPA release, leading to wind up • Release of prostaglandins, kinins that induce perivascular inflammation • NO and CGRP further capillary leakage

Pathophysiology • Potentials for future abortive treatment: • Antagonists of: CGRP, NO, Glutamate • Agonists of adenosine A1 receptors

Yeah, yeah and the moon is actually made of Gruyère not Emmental….. My patient still has her headache, so what do I give her?

Effective Abortive Agents • Triptans • Dihydroergotamine • NSAIDs • Anti-emetics • Lidocaine? • Opioids?

Triptans • 5-HT1B action: vasoconstriction by acting against NO • 5-HT1D action: inhibit CGRP release • Should be very effective, yet only 70-80% effective, with 50% headache recurrence. • Cardiac risk, side effects further limit use

Triptans • PO versions require 60-90 minutes to effect • 50% success rate PO vs. 75-80% s/c • Newer triptans offer no real advantage over original • Subset of patients do respond well to this abortive agent in home setting

Dihydroergotamine • Same 5-HT action, but slower binding • Impact of IM may require 2 hours • Nasal version requires up to 4 hours • If given IV may initially increase CGRP release, producing dramatic headache increase • Does not increase N&V • Most initial research success probably due to adjunctive anti-emetics

NSAIDs • Excellent for mild to moderate migraines • No effect on neurotransmitters • Direct inhibition of most perivascular inflammation • Ketorolac at best 50-60% success as abortive for severe migraines

Dopamine Antagonists • Phenothiazines • Butyrophenones • Metoclopramide

Dopamine Antagonists • High adverse event rate • Need to treat prophylactically: benztropine, lorazepam, diphenhydramine • Low headache recurrence rate • Only droperidol as effective IM as IV • Dysphoria cannot be treated, found to be horrible by some patients

Lidocaine • Intranasal lidocaine found effective in two studies, but of very short duration, 70% headache recurrence • Mechanism of action uncertain as blocks Na+ channels not Ca++ ones

Opioids • At best 50% effective, high recurrence rate • Often required in combination for complex cases • Biggest effect: allows patient to enter REM sleep, which shuts down dorsal raphe activity

So back to that lady: what are you going to give her? What should be your first choice?

Prochlorperazine 5 mg IV plus 1 mg benztropine • Droperidol 2.5 mg IM or IV plus benztropine • Sumatriptan 6 mg s/c

Analgesia-induced rebound headaches • Obtain good headache medication history • May occur with simple analgesics or with opioids • If cessation of medication may take 3 months to return to baseline headache frequency • DHE IV q8h x 2-3 days resolves problem

Migraine: headache recurrence • First identified 1989 • As high as 50-60% at 24 hours in some trials • Often as debilitating as original headache • Need to distinguish from analgesia rebound headache

Preventing recurrence • Innes et al: dexamethasone IV • Ducharme et al: complete elimination of pain before discharge • Choice of abortive agent • serotonin agonists have highest recurrence rate

Preventing Future Headaches • Headache diary: identifying triggers • Prophylaxis • Diet • Exercise • Sleep • Stress modification

Preventing Future Headaches • Medications: • Valproate: 45% patients more than placebo with 50% decrease in headache rate • Beta Blockers: 40% • Flunarazine: 42% • Pizotifen: 20% • Riboflavin: 37%

Your patient is pain free, leaves your ED with a smile, and you finish your shift … …. ….. With a throbbing headache of your own!

Migraine Headaches