To report a case of idiopathic hypereosinophilic syndrome (HES) complicated by extensive, multiterritorial strokes.

Case Report

A 66 year-old Haitian woman with hyperlipidemia, diabetes mellitus, coronary artery disease, and pulmonary hypertension presented with headache, chest pain and left arm weakness.  Neurological examination demonstrated right gaze preference, left homonymous hemianopsia, optic apraxia, ocular ataxia, left hemiparesis and neglect. Blood work revealed leukocytosis of 63.2×10³/µL, with eosinophils 52.1×10³/µL, neutrophils 6.9×10³/µL, and no blasts. Troponin was elevated to 1.81 ng/mL, and she was diagnosed with a non-ST elevation myocardial infarction.  Electrolytes, calcium, phosphorus, renal and liver function tests were normal. Brain MRI showed multiterritorial, scattered, embolic infarcts affecting both anterior and posterior circulations, right more than left hemispheres. CTA head and neck did not reveal large vessel occlusion. Transesophageal echocardiogram showed EF 60% with mild mitral regurgitation. No PFO or intracardiac source of embolus was identified. Cardiac MRI did not show definite evidence of infiltrative disease.  An extensive search for the cause of eosinophilia including infectious work up, bronchoscopy, transbronchial biopsy, peripheral blood flow cytometry, genetic testing, and bone marrow biopsy were unremarkable. The patient was initially heparinized and subsequently transitioned to aspirin and warfarin for secondary stroke prevention, as well as hydroxyurea and imatinib for management of the hypereosinophilia.

Idiopathic HES is a disorder defined by an absolute eosinophil count greater than 1500/µL for more than 6 months, of unclear etiology, in which eosinophilic infiltration and mediator release causes damage to multiple organs. While stroke is the most devastating neurological complications of HES, the association is not clearly understood. Postulated mechanisms include cardiomyopathy with secondary embolism, endothelial dysfunction, hyperviscosity and hypercoagulability. Treatment with anticoagulants alone has shown poor results, underscoring the importance of recognizing this condition, lowering the eosinophil count and better understanding the pathophysiology of the disease.