A<unk>  is a headache that is severe and has a sudden onset. It is defined as a severe headache that takes seconds to minutes to reach maximum intensity. Although approximately 75% are attributed to "primary" headaches—headache disorder, non-specific headache, idiopathic<unk> , or uncertain headache disorder—the remainder are secondary to other causes, which can include some extremely dangerous acute conditions, as well as infections and other conditions. Usually, further investigations are performed to identify the underlying cause.
Thunderclap headache
External compression headache
Cold-stimulus headache
Ictal headache
Tension headache
Lupus headache
Vascular headache
Cluster headache