The incidence of<unk>  is unknown, but it is believed to be "not uncommon", and likely under-diagnosed. One small, possibly biased study found that the condition was eventually diagnosed in 45% of outpatients with sudden headache, and 46% of outpatients with thunderclap headache. The average age of onset is 42, but<unk>  has been observed in patients aged from 19 months to 70 years. Children are rarely affected. It is more common in females, with a female-to-male ratio of 2.4:1.
Reversible cerebral vasoconstriction syndrome
Cerebral hyperperfusion syndrome
Brain fag syndrome
Intracranial hypertension syndrome
Cerebral vasospasm
Thrombotic storm
Posterior cerebral artery syndrome
Middle cerebral artery syndrome