Hyepreosinophilic syndrome (HES) is a persistent blood eosinophilia (1.5x10⁹/L for more than six consecutive months) resulting in end organ damage. The primary organs involved are the central and peripheral nervous system, heart, lungs, and skin.

A unique case of an  80-year right-handed man who presented with 4 days of malaise, cough, and fatigue with an acute onset right upper extremity weakness and notable gait instability. On examination he had right-sided hemiparesis with no facial droop in addition to right sided hyper-reflexia. CT head without contrast demonstrated multiple Intra-parencymal Hemorrhages (IPH) and Subarachnoid Hemorrhages (SAH), notable in the right parietal, left periventricular and occipital regions. MRI Brain without gadolinium demonstrated multiple cerebral and cerebellar diffusion restrictions suggestive of watershed infarction in addition to the forementioned IPH and SAH. Serum analysis revealed a leukocytosis (36.1 K/UL) with an eosinophilic predominance (40.4%). He was noted to have a tropinemia (Troponin T 1022.0ng/L). He subsequently became anuric and acutely confused. Transthoracic echocardiogram demonstrated a large left ventricular thrombus.  Subsequent digital subtraction angiogram demonstrated multiple aneurysms concerning for mycotic aneurysms. Blood cultures remained negative throughout his admission. Eosinophillic leukemia was ruled out on marrow studies. Anticoagulation was delayed for 1 week due to mycotic aneurysms, but the patient had recurrent strokes and was subsequently treated with full anticoagulation. His eosinophilia resolved with steroid therapy.

HES can present with acute confusion and gait difficulty with imaging demonstrating intra-cerebral hemorrhages. The thrombotic mechanism of HES is postulated to be, kallikrein system activation resulting in factor XII activation inducing a hypercoagulable state. Early recognition of HES can result in early treatment and reduce. Neurologists are often called for neurologic manifestations of systemic diseases such as HES. HES must be considered in the differential for acute multi-territorial strokes or hemorrhages in a patient with altered mental status.