Table 1 Critical elements for the diagnosis of RCVS.

Clinical features

Severe, acute ‘thunderclap’ headaches, with or without additional neurological signs due to (watershed) strokes, subarachnoidal haemorrhages

Associated conditions (e.g. medication, drugs, and blood products)

Radiological features

Conventional angiography or indirect CTA or MRA with ‘vasculitis-like’ multi-focal segmental cerebral artery vasoconstriction

Watershed (strokes)

Subarachnoidal haemorrhages (cortical)

No evidence for aneurysmal subarachnoid haemorrhage

Reversibility of angiographic abnormalities within 12 weeks after onset

Others

Normal or near-normal cerebrospinal fluid analysis (protein level < 80 mg%, leucocytes < 10 mm³, normal glucose level)