Chronic Cluster Headache Update and East–West Comparisons: Focusing on Clinical Features, Pathophysiology, and Management

Purpose of Review: This review provides an update on chronic cluster headache (CH) focusing on clinical features, pathophysiology, and management as well as comparisons between Eastern and Western populations. Recent Findings: Chronic CH in Eastern populations was relatively rare, compared to that in Western populations. Lacrimation and/or conjunctival injection is the most frequently reported cranial autonomic symptom, and visual aura is predominant in chronic CH patients. Neuroimaging evidence in both ethnic groups suggests that CH pathophysiology involves the hypothalamus and pain-modulatory areas, with dynamic alternations between CH episodes. Recent evidence indicates that midbrain dopaminergic systems may participate in CH chronicity. Noteworthy advances have emerged in neuromodulatory therapies for chronic CH, but treatment with calcitonin gene-related peptide (CGRP) monoclonal antibodies has been unsuccessful. Summary: Recent evidence shows divergence of chronic CH between Eastern and Western populations. Neuromodulatory therapies but not CGRP inhibition is effective in this intractable patient group.