Long-Term Outcome of Patients With Intractable Chronic Cluster Headache Treated With Injection of Onabotulinum Toxin A Toward the Sphenopalatine Ganglion - An Observational Study

Objectives-To investigate long-term outcomes in per-protocol chronic cluster headache patients (n = 7), 18 and 24 months after participation in "Pilot study of sphenopalatine injection of onabotulinumtoxinA for the treatment of intractable chronic cluster headache." Methods-Data were collected prospectively through headache diaries, HIT-6, and open questionnaire forms at 18 and 24 months after the first treatment. Patients had access to repeated injections when needed. Results-An overall significant reduction in cluster headache attack frequency per month (57.3 +/- 35.6 at baseline vs 12.4 +/- 15.2 at month 18 and 24.6 +/- 19.2 at month 24) was found. In addition, there was a reduction in attacks with severe and unbearably intensity (50.0 +/- 38.3 at baseline vs 10.1 +/- 14.7 at month 18 and 16.6 +/- 13.7 at month 24) and an increase in attack free days (4.2 +/- 5.9 at baseline vs 19.1 +/- 9.4 at month 18 and 12.9 +/- 8.8 at month 24). Conclusions-Our findings suggest sustained headache relief after repeated onabotulinumtoxinA injections toward the sphenopalatine ganglion in intractable chronic cluster headache. A placebo-controlled trial with long-term follow-up is warranted.