Stroke From Paradoxical Embolism in a Young Patient With Sickle-Cell Disease and High Fetal Hemoglobin: A Diagnostic Challenge.

Sickle-cell disease (SCD) is characterized by abnormal hemoglobin (Hb) polymerization, leading to erythrocyte sickling and microvascular obstruction. Elevated fetal hemoglobin (HbF) levels are often associated with reduced-but still possible-vaso-occlusive complications. We report the case of a 22-year-old South Asian male with SCD and persistently elevated HbF (~23%) who presented with transient right-sided numbness and visual disturbances. Brain MRI confirmed acute ischemic infarcts, prompting urgent red blood cell exchange transfusion. Comprehensive investigations for causes of stroke revealed a patent foramen ovale on echocardiogram, suggesting paradoxical embolism as the etiology. This case highlights diagnostic challenges in SCD patients with high HbF presenting with stroke. While elevated HbF levels are considered protective against vaso-occlusive events, this patient's presentation challenged this assumption. The identification of a cardiac shunt prompted reconsideration of the stroke mechanism. In conclusion, clinicians must maintain a broad differential diagnosis and pursue comprehensive evaluations in SCD patients with neurological symptoms.