Young WB, et al. - Researchers investigated the efficacy and safety of onabotulinumtoxinA in people with chronic migraine (CM) with and without allodynia in this subanalysis of the 108-week, multicenter, open-label COMPEL (Chronic migraine OnabotulinuMtoxinA Prolonged Efficacy open-Label) Study. They treated patients (n = 715) with onabotulinumtoxinA 155 U every 12 weeks for 9 treatment cycles. Patients with (n = 289) and without (n = 426) allodynia displayed a significant mean reduction in headache day frequency at week 108 relative to baseline in relation to onabotulinumtoxinA. For reduction in headache days, the allodynia group displayed a smaller treatment response, but in terms of improvement in other measures the groups were similar. they identified no new safety concerns.