Reversible cerebral vasoconstriction syndrome (RCVS) is a cerebrovascular disorder that is commonly associated with transient constriction of the cerebral arteries. RCVS most commonly occurs secondary to exposure of vasoactive substances. Only once has the disease been reported where polycythaemia vera (PV) was implicated to be the cause. We report a case in which PV was found at the same time as RCVS.

A 52-year-old female presented with a fulminant holocranial headache followed by vomiting as she was working. Magnetic resonance imaging (MRI) and brain magnetic resonance angiography (MRA) revealed subarachnoid haemorrhage along bilateral fronto-parietal sulci. Cerebral angiogram provided evidence of constricted vessels – this went unrecognised. She came to our institution 5 months later with similar complaints in addition to facial plethora and plethoric conjunctiva. Diffuse irregularities of the cerebral arteries were found with cerebral angiogram showing similar findings to brain MRA. A haematologist consult found positive JAK2 mutation, and with reference to blood count analysis, a diagnosis of PV was made. Treatment of PV included aspirin, hydroxyurea and oral nimodipine. Follow-up showed decreased facial plethora, decreased headache symptoms and no episodes of dysarthria

The patient presented to our institute 5 months after initial findings. Typically RCVS should resolve in 1-3 months. MRI showing evidence of infarction suggests that PV caused thrombotic event since cerebral vasoconstriction was improving. We hypothesize that the repeat thrombosis mechanisms’ anticonstricting effect was damaged following endothelial damage to vascular intima – leading us to believe RCVS is a repercussion of PV.