Treating migraine in the emergency department
Authors: Randolph W Evans
Journal: BMJ (2008)

In the accompanying systematic review, Colman and colleagues assess the effectiveness of parenteral corticosteroids for treating acute severe migraine and preventing recurrence.1 In Western Europe and the United States, about 12% of adults experience migraine each year, and 63% of these people have one to four migraines a month. Most people have nausea and moderate to severe pain, which results in severe impairment or requires bed rest, and one third have vomiting.2 If untreated, these headaches last for four to 72 hours, with a median duration of 24 hours.

In the US, only 56% of affected patients have received a medical diagnosis of migraine and instead believe that they have sinus, tension, or stress headache. About half of these people use over the counter drugs,3 which are effective in up to 59% of cases. But even with seven different types of triptans and various ways of giving them, 25% of patients do not respond.4

When triptans are initially effective, the pain recurs in up to 40% of instances and a second dose may not be effective or not taken. All drugs for symptomatic migraine are more effective if taken when the pain is mild. However, patients often delay taking drugs, or they sometimes wake from sleep with intense pain or cannot retain the drug because of vomiting. As the pain progresses, central sensitisation can cause cutaneous allodynia (pain provoked by stimulation of the skin that would ordinarily not produce pain; this is seen especially in the head and face, but it can also be generalised) and triptans are unlikely to be effective.5

Not surprisingly, people with migraine often seek help in the emergency department, where they account for around 2% of visits and may receive a less than warm welcome when they present with “just a headache.” This challenging group of people is made up of those with their first or worst attacks, those who have not taken or not responded to drugs, frequent attendees, those with acute exacerbation of chronic migraine, and those with migraine with neurological symptoms and signs (with aura).

In the emergency department, evidence based guidelines recommend the first line use of dihydroergotamine, subcutaneous sumatriptan, dopamine antagonists (metoclopramide, prochlorperazine, and chlorpromazine), and ketorolac, which have response rates of up to 70%.6 However, narcotic analgesics, recommended as rescue drugs, are still widely used, even though their administration may result in significantly longer stays in the emergency department compared with non-narcotic treatments.7

Migraine pain persists or recurs within 24 hours of discharge from the emergency department regardless of treatment in over half of patients.8 Animal studies suggest that migraine pain may be caused by sterile inflammation in the nerves, which is why it was proposed that corticosteroids might reduce inflammation, relieve the pain, and prevent recurrence.

In their meta-analysis, Colman and colleagues included seven randomised controlled trials (n=738) of intravenous dexamethasone (10-24 mg given once) for treatment of acute severe migraine headache and for preventing recurrence.1 There was no significant difference between dexamethasone and placebo for the immediate relief of acute migraine (weighted mean difference 0.37, 95% confidence interval −0.20 to 0.94). However, when added to standard treatment, intravenous dexamethasone significantly reduced headache within 72 hours (relative risk 0.74, 0.60 to 0.90). Nine patients need to be treated to prevent one recurrent headache, a modest response.

Although side effects were minor and similar between groups, repeated doses in regular attendees to the emergency department may increase the long term risk for osteoporosis or, rarely, aseptic osteonecrosis of the femoral head or knees.9 Caution should be used when treating people with diabetes, who may have raised blood sugars during the 36-72 hour half life of dexamethasone.

Future research on corticosteroids might clarify the interaction with other drugs used to treat migraine; the optimum dose; whether oral administration is effective; and whether subgroups of people, such as those with prolonged severe headaches, may benefit in particular.

For now, we should try to keep patients out of the emergency department by encouraging them to treat their symptoms early on; making triptans, antiemetics, and rescue drugs more available as appropriate; and prescribing preventive drugs. An oral antagonist of calcitonin gene related protein, which may be available in the next couple of years, might provide better sustained pain-free responses at 24 hours than triptans. However, its use depends on regulatory approval and an acceptable safety profile, and it is unclear how effective it will be in people who do not respond to triptans.10 Doctors and migraine advocacy groups should lobby for increased government funding for migraine research, which, annually, is only about $13m (£6.5m; €8.2m) in the United States and €6 million in Europe.11