Multiple Cerebral Infarcts and Encephalopathy as the First Clinical Manifestations of Hypereosinophilic Syndrome: A Case Report and Narrative Review

Abstract

Background: Hypereosinophilic syndrome is characterized by a peripheral blood eosinophil count >1.5 × 10³/μL on two different examinations within a month of each other and/or a 20% or higher percentage of eosinophils in a bone marrow section, associated with organ damage. Rarely, neurological manifestations may occur, even in the early stages. We report a case of idiopathic hypereosinophilic syndrome with Loeffler endocarditis presenting with multiple bilateral strokes and encephalopathy as the first clinical manifestations.

Summary: Hypereosinophilia and echocardiographic findings suggested a Loeffler's endocarditis. Blood hyperviscosity and small vessels inflammation induced by the hypereosinophilia itself, the embolization of intracardiac thrombus, along with the impaired clearance of microthrombi in the watershed areas, are the main mechanisms involved in the pathophysiology of stroke in the hypereosinophilic syndrome. Additionally, encephalopathy could be considered as a consequence of multiple cerebral infarcts and neurotoxicity induced by hypereosinophilia since our patient's confusion and aggressive behavior gradually remitted after steroid therapy was started.

Key messages: To the best of our knowledge, our case report is a rare instance highlighting neurological involvement as the earliest manifestation of hypereosinophilia. We aimed to elucidate the central nervous system involvement in this intriguing disorder, with the goal of encouraging clinicians to consider hypereosinophilic syndrome in the diagnostic assessment of rare stroke etiologies.

Keywords: Encephalopathy; Hypereosinophilic syndrome; Loeffler’s endocarditis; Stroke.

Fig. 1.

a EEG showing a frontotemporal sequence of rhythmic delta waves at 2 Hz preceded by point-wave-like graphoelements (GRDA + S). b Symmetrical watershed cerebral infarctions in the first DWI-brain MRI. c Symmetrical watershed cerebral infarctions in the second DWI-brain MRI.

Fig. 2.

a Transthoracic echocardiography showing a thickening of the apical lateral left ventricle wall. b STIR short axis cardiac MRI images showing the thickening of the anterior and lateral wall of the left ventricle. c STIR 4-chambers view showing subendocardial hyperintensity and LGE of the left ventricle anterior and lateral wall, in the middle of which a thrombus can be seen. LGE, late gadolinium enhancement.