Cluster headache not responsive to sumatriptan: A retrospective study

Introduction: Subcutaneous sumatriptan, a 5HT1B/1D agonist, is the most effective drug in cluster headache acute treatment. About 25% of the patients do not respond to subcutaneous sumatriptan; the reasons for this are unknown. In this study, we compare clinical characteristics of cluster headache patients responding and non-responding to subcutaneous sumatriptan. Methods: We retrospectively investigated the clinical records of 277 cluster headache patients. Patients reporting repeated satisfactory response to subcutaneous sumatriptan within 15 minutes were considered responders. Results: Of 206 cluster headache patients who had used subcutaneous sumatriptan (mean age 45.6, 16% females, 48% chronic), 91% were responders, and 9% non-responders. Compared to responders, non-responders had longer and more frequent attacks: 60 (median; IQR 38–90) vs. 100 (60–120) minutes (p = 0.028), 4 (2.5–5) vs. 3 (2–4) attacks/day (p = 0.024). No other difference was found. Conclusions: In cluster headache attacks with long duration and high frequency, pain mechanisms not involving 5HT1B/1D receptors may play a more relevant role.