Migraine headache is a painful condition of recurrent moderate to severe head pain associated with nausea, vomiting, photophobia, and phonophobia. The condition is highly prevalent and a significant community health problem with considerable impact on the health care system. To alleviate the pain and morbidity associated with a migraine attack, drug therapies are often employed including simple analgesics like ibuprofen and migraine-specific medications like sumatriptan. When these treatments fail or in severe, intractable cases, patients and families may present to the Emergency Department (ED).

Ketorolac in combination with metoclopramide or prochlorperazine was the most common multi-drug combination used in 36% of ED presentations for migraine across Canada in our national practice variation study. The scientific rationale for combining a non-selective non-steroidal anti-inflammatory drug (NSAID) with inhibition of both the cyclooxygenase (COX) 1 and 2 isoenzymes with other migraine therapies is enticing; however, no studies have specifically examined the relative efficacy of the practice. Why would the combination of a non-selective NSAID like ketorolac with other migraine therapies improve treatment outcomes? The benefit of multi-target combinations may be relate to the duration of the migraine and the multiple brain areas involved in sustained pain. It has long been recognized that patients who treat their migraine headaches early at the onset have a better response. The underlying mechanism for this phenomenon has now been identified. The initiation of migraine pain requires activation of the trigeminal (5th cranial nerve) nociceptive (pain) system. Activation of these sensory fibers within the arachnoid membrane on the surface of the brain produces the first and most common painful manifestation of migraine - the pulsatile headache. With each heartbeat, minor dilation of the cerebral blood vessels produces stretch and a painful activation of the trigeminal fibers known as peripheral sensitization. The second phase in the maintenance of a migraine attack over several hours is the sensitization of trigeminal pain pathways leading to higher brain centers known as central sensitization. The efficacy of medications like the triptans is greater early in the course of a migraine attack when there is only peripheral sensitization and before the onset of central sensitization. Non-selective NSAIDs like naproxen sodium and ketorolac may be uniquely effective in the reduction of central sensitization in the animal model of migraine and the reduction of migraine pain in adult patients late in the course of a migraine headache.

The population of patients in the ED is uniquely different from outpatients in that most have developed their migraine headache hours or days before presenting. In our practice variation study, the mean duration of the migraine prior to presenting to the ED was 2 days. Including an NSAID when treating a prolonged migraine in the ED may thus increase the therapeutic window and improve outcomes. While many Canadian ED physicians have adopted the practice of combining ketorolac with other migraine therapies, the gold standard assessment of efficacy and safety in a randomized clinical trial has not been applied.