Clinical significance of brush allodynia in emergency patients with migraine

Background. - Cutaneous brush allodynia may be a practical and readily assessable marker of progression of an acute migraine attack. We determined the relative frequency of this finding in emergency department (ED) patients with acute migraine and tested the hypothesis that the presence of cutaneous brush allodynia prior to initial treatment in the ED could predict poor 2-hour and 24-hour pain intensity outcomes. Methods. - As part of a multicenter ED-based clinical trial testing the benefit of dexamethasone vs placebo for the adjuvant parenteral treatment of acute migraine, cutaneous brush allodynia was assessed prior to treatment using an established methodology. In addition to dexamethasone or placebo, all patients received intravenous metoclopramide + diphenhydramine as primary treatment for their migraine. Pain intensity outcomes were assessed in the ED 2 hours after medication administration and again by telephone 24 hours after medication administration. Results. - An assessment of cutaneous brush allodynia was performed in 182 migraineurs from 3 different EDs, of whom 26 (14%, 95% CI: 10-20%) had cutaneous brush allodynia. A pain-free state within 2 hours of medication administration was achieved by 46% of the allodynic patients and by 47% of the nonallodynic patients (P =.91). Median headache intensity over the 24 hours after ED discharge, as measured on a pain intensity scale from zero to 10, was 3 in the allodynic patients and 3 in the nonallodynic patients (P =.23). Conclusions. - Cutaneous brush allodynia is an uncommon finding in the ED, occurring in fewer than 1 in 5 migraineurs. It does not seem to have prognostic relevance for the ED-based management of the acute migraine attack.