What is cluster headache? It is characterized by episodes of severe pain around one orbit, with repeated and intensive attacks, accompanied by autonomic symptoms such as ipsilateral conjunctival congestion, tearing, pupil narrowing, eyelid drooping, and sweating on the head and face, often at fixed times of the day, lasting more than 10 minutes to 180 minutes each time, and the attacks can last for weeks to months. Most of the attacks occur in the same season of the year or at intervals of several years. Zhu Kaiyun, Department of Neurology, Panyu District Hospital of Traditional Chinese Medicine, Guangzhou, China