The efficacy of botulinum toxin type-A for intractable chronic migraine patients with no pain-free time.

AIM: This is a retrospective report of the efficacy of botulinum toxin-A, Botox® (Allergan), in intractable chronic migraine patients non-responsive to previous pharmacological management and with largely no pain-free time, including those with new onset daily persistent headache. METHODS: Thirty-three patients, all with severe Headache Impact Test (HIT)-6 scores at baseline, received 3-monthly injections of Botox® as per Phase III REsearch Evaluating Migraine Prophylaxis Therapy (PRE-EMPT) protocol over a maximum 33-month period. Response criteria were a sustained reduction of HIT-6 scores below 60. RESULTS: Four patients had headache on at least 20 days a month; the remaining patients had daily headache with no pain-free time, including nine patients with new onset persistent migraine. There was a significant reduction in HIT-6 scores following Botox® therapy (x̅ = -5.45, p = 0.000920). Twenty-one percent of the cohort exhibited a sustained reduction in HIT-6 scores below 60. The number of headache days and pain-free time did not change in five of the six responders, but disability improved. There was no difference between patients with episodic migraine evolving to chronic as opposed to those with chronic migraine from onset. CONCLUSION: This report suggests that Botox® treatment is efficacious in intractable chronic migraine without pain-free time. The HIT-6 is a reliable and practical parameter to assess disability in this patient group. Use of such validated parameters should be considered with greater weight in future International Classification of Headache Disorders (ICHD) guidelines for controlled clinical trials.