To describe 3 cases of stroke associated with hypereosinophilic syndrome and discuss the pathogenesis of such strokes. Retrospective medical record review. University hospital. Three patients who had strokes temporally correlating with eosinophilia with no other obvious causes of stroke. Retrospective review of the hospital course, laboratory data, imaging, treatment, and outcome. All 3 patients had multiple strokes in both hemispheres. Two patients with modest eosinophilia that was controlled quickly had infarcts mostly in arterial border zones and had good outcomes. The third patient with severe and more refractory eosinophilia had a poor outcome. Cardiac emboli and direct eosinophil toxicity contribute to strokes in hypereosinophilic syndrome. Prognosis is variable with use of anticoagulation and antiplatelet agents but rapid lowering of the eosinophil count results in a better outcome.
