Improved identification of allodynic migraine patients using a questionnaire

Abstract

Using quantitative sensory testing (QST), we found that many migraineurs seeking secondary and tertiary care exhibit cutaneous allodynia whenever they undergo a migraine attack, but not interictally (i.e. between attacks). When such patients were questionned interictally in the clinic about symptoms of skin sensitivity in past attacks, 76% of them were 'correctly' classified either as allodynic (>or=1 symptom) or non-allodynic (zero symptoms) in line with the QST analysis. In this study, patients were classified as allodynic if they documented any one symptom of allodynia during an actual migraine attack which they had already cited in an earlier interictal interview. Of a total of 151 patients, 77% were classified as allodynic, citing on average four symptoms of skin hypersensitivity, three of which were consistently cited in the interictal interview and again during an attack. Among the remaining 23% of patients who were classified as non-allodynic, half cited zero symptoms as expected, while the other half cited between one and five symptoms, each of which was cited either interictally or during an attack, but not in both. Further analysis showed that 97% of patients citing two or more symptoms during an attack consisted of the patients labelled as allodynic, and that 75% of those citing just one symptom during an attack consisted of patients labelled as non-allodynic. Short of QST analysis, the results suggest that about 90% of all patients can be identified as allodynic or non-allodynic depending on whether or not they (i) consistently cited the same item(s) both interictally and during an attack or, alternatively, (ii) cited two or more symptoms during an attack.

Figure 1

Percentage of allodynic (A, C) and non-allodynic (B, D) patients citing symptoms of skin hypersensitivity in the interictal interview and during an attack. Numbers above bars indicate actual number of patients. A vs. B or C vs. D: p<0.0001, Mann-Whitney U-test. A vs. C or B vs. D: p>0.22, Wilcoxon matched-pairs signed-rank test.

Figure 2

Distribution of allodynic (black) and non-allodynic (gray) patients according to the number of symptoms of skin hypersensitivity cited during a migraine attack. Note that 75% of patients citing a single symptom were non-allodynic.