cluster headache
Medical term for a severe headache that occurs in cyclical patterns or clusters.
Cluster headaches cause intense pain behind the eye.
片頭痛 (migraine) is a different type of headache, often with aura and unilateral throbbing pain, while 群発頭痛 occurs in clusters with severe, piercing pain around one eye.
Compound of 群発 (group occurrence) and 頭痛 (headache), reflecting the clustered pattern of attacks.