Abstract
Thunderclap headache is a severe and explosive headache that reaches maximum intensity at or within 60 seconds of onset. Primary thunderclap headache lasts from 1 hour to 10 days and diagnosis can be made only after exclusion of other disorders.
First, every thunderclap headache must be considered symptomatic of, for example, subarachnoid haemorrhage, cerebral venous sinus thrombosis or cerebral artery dissection. Reversible cerebral vasoconstriction syndrome is also characterised by thunderclap headache, with or without neurological symptoms and with constriction of cerebral arteries that resolves within three months without evidence of subarachnoid haemorrhage.