Clinical Profile of Chronic Cluster Headaches in a Regional Headache Center in Japan.

Objective Little is known about the prevalence and characteristics of chronic cluster headache (CCH) in Japan. We therefore characterized the clinical profile of CCH in Japan by surveying patients with CCH who were registered at a Japanese regional headache center. We also reviewed the existing literature for the prevalence and clinical characteristics of CCH reported in various populations. Methods In this single-center retrospective study, we assessed consecutive patients with cluster headache (CH) who visited a regional tertiary headache center between February 2011 and July 2020. They were treated following the Clinical Practice Guideline for Chronic Headache 2013. We compared their demographic characteristics and clinical features according to the CCH onset pattern (primary vs. secondary). Results Of 420 patients with CH, 19 (4.2%) had CCH (9 primary and 10 secondary). The incidence of CCH in Japan is relatively low compared to that in Western countries but is comparable to that in other Asian countries. CCH showed a higher predominance of men than women. Compared to primary CCH, secondary CCH included a higher proportion of current smokers and older patients during clinic visits. Subcutaneous sumatriptan and oxygen inhalation were the most common abortive treatments, and oral prednisolone and verapamil were the most common preventive treatments. Home oxygen therapy was effective in six of seven patients. Only two patients with coexisting migraine received calcitonin gene-related peptide (CGRP)-targeted therapies. Conclusions CCH remains refractory to treatment. Improving treatment outcomes will require maximizing the use of currently available drugs and expanding the use of neuromodulation, nerve block, and CGRP-targeted therapies.