Reversible cerebral vasoconstriction syndrome.

Reversible cerebral vasoconstriction syndrome (RCVS) is an under-recognised condition. It is characterised by sudden and severe headaches (of "thunderclap" type) associated with multifocal reversible narrowing of the intracranial arteries on neuroradiology. The diagnosis is often established with the resolution of headaches and vasoconstriction. We report two patients with RCVS and review the available literature, to clarify the diagnostic criteria and discuss the treatment options.