Cluster headache (CH) pain is the most severe of the primary headache syndromes. 
It is characterized by periodic attacks of strictly unilateral pain associated 
with ipsilateral cranial autonomic symptoms. The majority of patients have 
episodic CH, with cluster periods that typically occur in a circannual rhythm, 
while 10% suffer from the chronic form, with no significant remissions between 
cluster periods. Sumatriptan injection or oxygen inhalation is the first-line 
therapy for acute CH attacks, with the majority of patients responding to either 
treatment. The calcium channel blocker verapamil is the drug of choice for CH 
prevention. Other drugs that may be used for this purpose include lithium 
carbonate, topiramate, valproic acid, gabapentin, and baclofen. Transitional 
prophylaxis, most commonly using corticosteroids, helps to control the attacks 
at the beginning of a cluster period. Peripheral neural blockade is effective 
for short-term pain control. Recently, the therapeutic options for refractory CH 
patients have expanded with the emergence of both peripheral (mostly occipital 
nerve) and central (hypothalamic) neurostimulation. With the emergence of these 
novel treatments, the role of ablative surgery in CH has declined.