The Unlucky Variant: Artery of Percheron Infarction.

This case highlights the clinical significance of a rare ischemic stroke due to an artery of Percheron (AOP) infarction. If the AOP becomes blocked, it can lead to an infarct in the paramedian thalami and mesencephalon. AOP infarcts typically present with bilateral thalamic ischemia, a condition that can be challenging to diagnose due to its rarity and nonspecific symptoms. These infarcts are extremely rare, comprising only 0.1-2% of all ischemic strokes, and are often underdiagnosed. In this case, the patient presented with obtundation and later developed third cranial nerve palsy and diplopia, underscoring the need for heightened clinical awareness of atypical stroke presentations. A 69-year-old female with a past medical history significant for Ménière's disease (included due to initial overlap with altered sensorium or vertiginous presentation), hyperlipidemia, and bradycardia, who presented with obtundation. Initial CT imaging and video electroencephalogram were unremarkable. The patient's mental status improved over time, but she subsequently developed a third cranial nerve palsy and diplopia. An MRI brain revealed bilateral thalamic diffusion restriction and edema without enhancement, consistent with bilateral thalamic ischemic infarcts in the AOP territory. The patient was started on dual antiplatelet therapy (DAPT) for 21 days for secondary stroke prevention. A CT venogram (CTV) was ordered to rule out venous sinus thrombosis (VST). Additionally, an implantable loop recorder (ILR) was placed to monitor for potential atrial fibrillation as a possible source of cardioembolic stroke during outpatient follow-up. This case highlights the complexity of diagnosing and managing AOP infarction, a rare type of stroke.