Can allodynic migraine patients be identified interictally using a questionnaire?

Objective: The gradual development of cutaneous allodynia during the course of a migraine attack is commonly detected by quantitative sensory testing (QST) in migraineurs seeking secondary and tertiary medical help. In this study, the authors developed a questionnaire that tested the recollection of the patients on their skin sensitivity during past migraine attacks. Methods: The authors devised a series of questions regarding skin sensitivity during migraine and posed them to 89 migraineurs when they were free of migraine (Visit 1). To validate their recollections, the authors determined the patients' pain thresholds to mechanical and thermal skin stimuli in the absence of migraine (Visit 1) and during an attack (Visit 2), using QST. Results: Whereas 75.3% of the patients testified to at least one type of skin hypersensitivity during migraine, 24.7% were unaware of any abnormal skin sensitivity. The questionnaire correctly identified 84.8% of the 66 patients classified as allodynic by QST and mislabeled the remaining 15.2% as nonallodynic (false negatives). Among the 23 patients classified as nonallodynic by QST, 47.8% were mislabeled as allodynic using the questionnaire (false positives). Among the total number of 89 patients studied, the questionnaire produced 62.9% true positives and 13.5% true negatives (= 76.4% correct labeling) vs 12.4% false positives and 11.2% false negatives (= 23.6% mislabeling). Conclusion: The reliability of the questionnaire as a diagnostic tool of allodynia varies with the proportion of allodynic patients in a given clinic. The major source of variability is the misconception of nonallodynic patients that their skin is hypersensitive during migraine.