Cluster Headache

Cluster headache is a primary trigeminal autonomic cephalalgia characterized by severe unilateral periorbital pain occurring in circadian or circannual clusters. Pathophysiology involves hypothalamic dysfunction and trigeminal-autonomic activation. Clinical features include excruciating pain, lacrimation, nasal congestion, and restlessness during attacks. Diagnosis is clinical, based on attack frequency, duration, and associated autonomic features. Management includes acute therapy (oxygen, triptans), preventive medications (verapamil, lithium), and neuromodulation for refractory cases; prognosis is generally favorable, though attacks can recur over decades.