High-intensity headache of abrupt onset, mimicking that of ruptured cerebral aneurysm, in the absence of any intracranial pathology.
Diagnostic criteria:
A. Severe head pain fulfilling criteria B and C
B. Abrupt onset, reaching maximum intensity in <1 min
C. Lasting for ≥5 min
Source
Headache Classification Committee of the International Headache Society (IHS) (2013). The International Classification of Headache Disorders, 3rd edition (beta version). Cephalalgia 2013; 33: 9-807.