The effect of haloperidol administration on relieving cluster headache, probable role of dopaminergic pathway; a double blind clinical trial

Background: The present study was carried out with the aim of assessing the effectiveness of ۲.۵ mg dose of haloperidol compared with its standard ۵ mg dose in relieving symptoms of cluster headaches and finding out to what extent the dopaminergic pathway affects the incidence of cluster headaches.Methods: The present study is a double-blind randomized clinical trial carried out in ۳ health centers, Tehran, Iran. Patients diagnosed with cluster headache were treated by intravenous administration of ۲.۵ and ۵ mg of haloperidol. Using a standard visual analog scale, pain severity was recorded before and ۳۰, ۶۰, ۹۰, and ۱۲۰ minutes after intervention. Treatment success (at least ۳ points decrease in pain severity), side effects and recurrence of the headache were evaluated.Results: Finally, ۴۲ patients were treated with ۲.۵ mg dose of haloperidol and ۴۱ were in the ۵ mg dose haloperidol treatment group. ۴۰ (۹۵.۲%) patients who were treated with ۲.۵ mg dose of haloperidol experienced a significant decrease in pain (at least ۳ points decrease in pain severity) in the initial ۳۰ minutes. During this time, all of the patients (success rate=۱۰۰%) treated with ۵ mg dose of the drug had a significant decrease in pain. The two doses did not have a significant difference regarding treatment success (p=۰.۴۲).Conclusion: Results of the present study showed that both ۲.۵ and ۵ mg doses of haloperidol have similar effectiveness in reducing cluster headaches. The high success rate observed indicates that hyperactivity of dopaminergic pathway plays an important role in onset of cluster headaches.