Clarification of developing and established clinical allodynia and pain-free outcomes

The aim of this study was to determine whether clinical indicators of cutaneous allodynia predict the success of migraine therapy with sumatriptan using a brief questionnaire.

Using quantitative sensory testing (QST) recent studies demonstrate that the presence of cutaneous allodynia, a clinical manifestation of central sensitization, can be detrimental to the success of migraine therapy with sumatriptan. QST is costly and requires much time, therefore it is not feasible to use in clinical practice.

In this prospective study, migraineurs completed a questionnaire about their skin sensitivity during migraine. Each migraineur treated 2 migraine headaches with sumatriptan (100 mg): 1 headache at the earliest sign of migraine pain (mild, within 1 hour of onset) and 1 headache at least 4 hours after the onset of pain while moderate or severe.

Thirty-six migraine headaches were evaluated in 18 migraineurs. A total of 44% of the headaches were not associated with allodynia at any time. Irrespective of allodynic status, headaches were more likely to become pain-free with early versus late treatment (2 hours; 78% vs. 33%, respectively). Headaches were equally likely to become pain-free when allodynia was reported before treatment but not 2 and 4 hours after treatment (2 hours; 67 vs. 63%, respectively, 4 hours 80 vs. 81%, respectively). However, no headaches were pain-free when allodynia was reported at 2 and 4 hours after treatment.

Headaches without allodynia were aborted when treated early or late, and headaches with allodynia were aborted only when allodynia was not present after treatment. These findings suggest that different mechanisms account for allodynia before and after treatment; a developing phase in which central sensitization depends on incoming pain signals from the peripheral nociceptors and an established phase in which the sensitization becomes independent of the pain signals that come from the dura.