ROME—If triptan treatment fails to resolve a given migrain attack, cutaneous allodynia may point to the culprit. Investigators from Harvard Medical School in Boston found that failure of triptans to abort migraine is highly associated with the presence of fully established cutaneous allodynia at the time of treatment. The study, reported at the 11th Congress of the International Headache Society, also provides evidence to support the importance of patients taking their medications as soon as the pain starts—before allodynia becomes established, they said.

EXPLAINING INEFFICACY

Numerous studies have long shown that migraineurs are rendered pain-free within two hours (sustained for 24 hours) of triptan therapy in about 50% of all migraine attacks. Rami Burstein, PhD, Associate Professor of Anesthesia and Neurobiology at Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, said that the reason the overall rate of success has not been higher is because many patients resort to triptan therapy when their migraine has gotten complicated by a neural mechanism that underlies the adverse signs of cutaneous allodynia. The data of his prospective study of 61 migraine attacks suggest that the presence of fully established cutaneous allodynia at the time of treatment is detrimental to the efficacy of triptans among many migraine patients.

“We found that triptan treatment successfully resolved migraine in 93% of the attacks that we treated in the absence of cutaneous allodynia, but only in 15% of the attacks that we treated in the presence of allodynia,” reported Dr. Burstein. “Most importantly, allodynic individuals who failed to respond to late triptan treatment in one migraine attack responded just fine in another attack if treatment was given early enough before the establishment of allodynia. Therefore, we are suggesting that vigilant timing of triptan therapy can boost the success rate significantly and render almost all patients pain free,” he said.

TIMING IS EVERYTHING

Based on the timetable for the development of cutaneous allodynia, Dr. Burstein introduced triptans during the developing phase and the established phase in migraineurs with allodynia and during early and late phases in migraineurs without allodynia, and compared the results.

“We found that as long as migraine attacks are not associated with allodynia at the time of treatment, triptans are very effective at rendering these patients completely pain free regardless of whether the treatment is given early or late into the attack. In contrast, when migraine attacks are associated with allodynia at the time of treatment, triptans can only reduce the pain partially (by 20% to 40%), but not eliminate it completely” when the patient does not receive triptans within the first hour of the migraine onset, he said.

To test those findings, Dr. Burstein injected a nonallodynic patient with triptans during two separate migraine attacks, once at one hour and once at four hours. In both cases, the patient was rendered pain free.

In a migraine patient with allodynia, however, when triptans were administered four hours after onset of migraine, when skin sensitivity had been abnormal for several hours and the patient was probably in the established phase of allodynia, the triptan injection did not abort the migraine or treat the allodynia, he reported. In the same patient, using the same drug at one hour—when the allodynia was just beginning—an injection aborted the migraine and rendered the patient pain free.

NR

—Larry Schuster

Suggested Reading
Burstein R, Jakubowski M. Analgesic triptan action in an animal model of intracranial pain: a race against the development of central sensitization. Ann Neurol. 2003;55;Epub ahead of print.

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