Reversible Cerebral Vasoconstriction Syndrome (RCVS) is a group of conditions characterised by prolonged but reversible multifocal narrowing of the cerebral arteries. It presents typically as acute severe headache, usually recurrent and thunderclap in character, with or without additional symptoms and signs. Adverse complications associated with RCVS can be devastating especially if not recognised early; depending on the degree of vasoconstriction, RCVS may be associated with cortical subarachnoid haemorrhage (in approximately 34% of patients), ischaemic infarction (6-39% of patients), or concomitant posterior reversible encephalopathy syndrome (PRES, 9-38% of patients). RCVS may also present as parenchymal brain haemorrhage in 20% of cases. The data on complications rate highlight the uncertainty about the condition and indicate need for more research to better characterise the evolution of the pathology; hence need for this study as it is prospective and longitudinal.