Reversible cerebral vasoconstriction syndrome (RCVS) is characterised by severe, often recurrent thunderclap headaches with or without seizures and focal neurological deficit. Radiologically, there are multifocal segmental constrictions of the cerebral arteries that resolve spontaneously in 1-3 months. In more than half of cases RCVS is secondary, mainly postpartum and occurs after exposure to vasoactive substances. RCVS is clinically important as it affects in most cases young women and can be complicated by ishaemic or haemorrhagic stroke.
The differential diagnosis of RCVS includes subarachnoid haemorrhage, cerebral vasculitis, cerebral vascular thrombosis and cervicoencephalic arterial dissections. In absence of a randomised trial, treatment is based on expert opinion and case reports. At first it is advised to avoid triggers. Nimodipine seems to reduce thunderclap headaches within 48 to 72 hours but has no definite effect on haemorrhagic or ischaemic complications.