Cluster headache: pathophysiology, diagnosis and treatment

Cluster headache (CH) is characterized by attacks of severe, strictly unilateral pain that is orbital, supraorbital, temporal, or any combination of these, lasts 15–180 min, and occurs from once every other day to eight times a day. The pain is associated with ipsilateral conjunctival injection, lacrimation, nasal congestion, rhinorrhea, forehead and facial sweating, miosis, ptosis and/or eyelid edema, and/or with restlessness or agitation. The understanding of the pathophysiological mechanisms behind CH is far from complete, but CH is considered to be a neurovascular and chronobiologic headache disorder, with a pivotal role played by the central brain mechanisms. The diagnosis of CH is based on a careful history that elicits the clinical features of attacks, ipsilateral autonomic phenomena, and the cyclical nature of the bouts in which the attacks occur. Additional diagnostic interventions are needed to rule out secondary causes of CH. The main focus of therapy is to abort attacks once they have begun and to prevent future attacks. Alternative interventions in patients with CH who have not experienced any meaningful benefit from preventive drugs are well defined. Although there have been advances in the diagnosis and therapy of CH, a significant number of CH patients experience misdiagnoses and diagnostic delay, which stalls the possibility of the timely application of adequate abortive and preventive therapy.