Diffusion-weighted magnetic resonance imaging in two patients with polycythemia rubra vera and early ischemic stroke.

Polycythemia rubra vera (PRV) is a rare myeloproliferative disorder with a high risk of ischemic stroke. Although thrombosis of large cerebral arteries is the most frequently presumed pathomechanism, various infarct patterns have been described in patients with PRV and ischemic stroke. We report two patients with mild acute ischemic strokes and known PRV, in whom a scattered lesion pattern was detected by diffusion-weighted magnetic resonance imaging (DWI), but was not visible on computed tomography (CT) and conventional magnetic resonance imaging (MRI). Further diagnostic work-up including extra- and transcranial Doppler sonography (ECD, TCD), transesophageal echocardiography (TEE), magnetic resonance angiography and Holter monitoring revealed no obvious sources of cerebral embolism in both cases. However, TEE in one patient demonstrated spontaneous echo contrast (SEC) in the left atrium. In both patients the symptomatology resolved completely. The detection of a scattered infarct pattern by DWI in patients with PRV and acute ischemic stroke has not been reported previously. DWI findings together with the SEC in one patient emphasize the assumption that a prothrombotic state with subsequent arterial embolism rather than local arterial thrombosis may be the underlying pathomechanism of stroke in some patients with PRV. Adding DWI to the diagnostic work-up may help to clarify etiology in patients with PRV and acute ischemic stroke.