Ischemic stroke associated with amyloid‐related imaging abnormalities in a patient treated with lecanemab

INTRODUCTION Anti‐amyloid antibody therapies such as lecanemab are increasingly being used to treat Alzheimer's disease (AD). These therapies are associated with a high rate of amyloid‐related imaging abnormalities (ARIA). METHODS We review the case history of a patient who developed ARIA associated with lecanemab treatment. RESULTS In addition to microhemorrhages and cerebral edema that are recognized features of ARIA, the patient developed several ischemic strokes. The patient also experienced frequent electrographic seizures without overt clinical seizures. The patient demonstrated clinical and radiographic improvement after steroid treatment. DISCUSSION Our case suggests that ischemic strokes may be a feature of ARIA and highlights the importance of having a high clinical suspicion for seizures in ARIA. As anti‐amyloid therapies are likely going to be increasingly used to treat AD, it is important to appreciate the spectrum of clinical and radiographic findings that can result as side effects from this class of therapies. Highlights We report a patient who developed severe amyloid‐related imaging abnormalities (ARIA) after treatment with lecanemab. Our report suggests that ischemic strokes may be a novel imaging feature of ARIA. Our report highlights the need for high clinical suspicion for seizures in ARIA.