Polycythaemia as the cause of ischaemic stroke

Patients with polycythaemia vera are at high risk for vasoocclusive disease including cerebral ischaemia. Although unusual acute ischaemic stroke may be the ist manifestation of polycythaemia vera. It has been thought that cerebral ischaemic events have been due to increased blood viscosity and platelet activation within CNS. However some due to microembolic events originating outside brain. Some may also present with bleeding from nose or other sites due to excessive platelet and defect in function of vwf.