Abstract
RATIONALE: Few reports of idiopathic hypereosinophilic syndrome exist presenting as ischemic cerebrovascular disease, and the majority are watershed infarction. We report the first case of idiopathic hypereosinophilic syndrome that has clinical features of capsular warning syndrome lasting 6 weeks. PATIENT CONCERNS: A 26-year-old man complained of recurrent right limb weakness, accompanying slurred speech, and right facial paresthesia. DIAGNOSES: The patient was diagnosed with idiopathic hypereosinophilic syndrome (IHES). INTERVENTIONS: Adequate glucocorticoid and anticoagulant treatments were given. OUTCOMES: The patient's motor ability improved, and he was discharged 2 weeks later. Muscle strength in the right-side extremities had fully recovered at a 3-month follow-up after discharge. LESSONS: This case suggests that idiopathic hypereosinophilic syndrome should be considered as a cause of capsular warning syndrome, and the dose of glucocorticoid and the efficacy evaluation index needs to be reevaluated for the treatment of ischemic cerebrovascular disease associated with idiopathic hypereosinophilic syndrome.