Onabotulinumtoxin A for prophylaxis in chronic migraine: preliminary data from Headache Regional Centre of Aosta Valley.

Chronic migraine (CM) is a complex neurological disorder associated with substantial disability that affects approximately 2 % of general population. Onabotulinumtoxin A is employed for patients suffering from CM refractory to common therapeutic prophylaxis. Since May 2013, we have selected 22 patients referring to our headache centre with a history of CM which meets the diagnostic criteria of ICHD-3 beta (2013). The patients have been treated with onabotulinumtoxin A injection in 31 sites according to the protocol of the PREEMPT study at the total dosage of 155 U/treatment every 3 months. So far, eight patients have been subjected to three treatment sessions, five patients to two treatments and nine patients to one treatment. Three patients dropped for low compliance, but there were no serious adverse events. The frequency of headache days, the intensity of headache and the headache disability have been measured using headache diary, migraine disability assessment (MIDAS) questionnaire and headache impact test (HIT)-6 score. Data concerning the 13 patients who have been submitted to at least two treatment sessions have already shown a decrease of headache days of 20.64 % after the first treatment; MIDAS and HIT-6 scores have been significantly improved with a reduction of the scores, respectively, of 38.45 % for MIDAS and of 6.95 % for HIT-6. These are preliminary results because the observation time, the number of treatment sessions and the number of patients treated are still few.