Reversible cerebral vasoconstriction syndrome.

Reversible cerebral vasoconstriction syndrome is characterised by severe headaches with or without seizures and focal neurological deficits, and constriction of cerebral arteries which resolves spontaneously in 1-3 months. It affects females slightly more than males, and mean age of onset is around 45 years. Approximately 60% of cases are secondary, mainly postpartum and after exposure to vasoactive substances. The major complications are localised cortical subarachnoid haemorrhage (22%) and parenchymal ischaemic or haemorrhagic strokes (7%) which may leave permanent sequelae. Diagnosis requires the demonstration of the "string of beads" appearance of cerebral arteries on angiography, with complete or almost complete resolution on repeat angiography 12 weeks after onset. Nimodipine seems to reduce thunderclap headaches within 48 h but has no definite effect on the haemorrhagic and ischaemic complications.