Cutaneous allodynia in the migraine population.

OBJECTIVE

To develop and validate a questionnaire for assessing cutaneous allodynia (CA), and to estimate the prevalence and severity of CA in the migraine population.

METHODS

Migraineurs (n = 11,388) completed the Allodynia Symptom Checklist, assessing the frequency of allodynia symptoms during headache. Response options were never (0), rarely (0), less than 50% of the time (1), > or = 50% of the time (2), and none (0). We used item response theory to explore how well each item discriminated CA. The relations of CA to headache features were examined.

RESULTS

All 12 questions had excellent item properties. The greatest discrimination occurred with CA during "taking a shower" (discrimination = 2.54), wearing a necklace (2.39) or ring (2.31), and exposure to heat (2.1) or cold (2.0). The factor analysis demonstrated three factors: thermal, mechanical static, and mechanical dynamic. Based on the psychometrics, we developed a scale distinguishing no CA (scores 0-2), mild (3-5), moderate (6-8), and severe (> or = 9). The prevalence of allodynia among migraineurs was 63.2%. Severe CA occurred in 20.4% of migraineurs. CA was associated with migraine defining features (eg, unilateral pain: odds ratio, 2.3; 95% confidence interval, 2.0-2.4; throbbing pain: odds ratio, 2.3; 95% confidence interval, 2.1-2.6; nausea: odds ratio, 2.3; 95% confidence interval, 2.1-2.6), as well as illness duration, attack frequency, and disability.

INTERPRETATION

The Allodynia Symptom Checklist measures overall allodynia and subtypes. CA affects 63% of migraineurs in the population and is associated with frequency, severity, disability, and associated symptoms of migraine. CA maps onto migraine biology.