====== Cluster headache ====== >Cluster headache (CH) always involves pain that is one sided (although it can switch sides) and the main defining feature is the association with one or more of the 'cranial autonomic' features normally described as follows: >• Reddening and tearing of the eye • A runny or blocked nostril • Droopy eyelid • Constriction of the pupil • Flushing and facial sweating __There is, as yet, no known cause for cluster headache.__ However, cluster headache has two major clinical features: the trigeminal (nerve) distribution of pain and the associated ipsilateral (same-sided) autonomic symptoms." //Source// [[https://ouchuk.org/what-is-cluster-headache|Organisation for the Understanding of Cluster Headache]] based at UK's Royal Free Hospital and King's College Hospital. ---- Also see: [[content:medicine:diseases:m-q:migraine|Migraine]]