Acute Onset of Hypersomnolence and Aphasia Secondary to an Artery of Percheron Infarct and a Proposed Emergency Room Evaluation.

Artery of Percheron (AOP) is a rare anatomical variant, which supplies bilateral paramedian thalami and the rostral mesencephalon via a single dominant thalamic perforating artery arising from the P1 segment of a posterior cerebral artery. AOP infarcts can present with a plethora of neurological symptoms: altered mental status, memory impairment, hypersomnolence, coma, aphasia, and vertical gaze palsy. Given the lack of classic stroke signs, majority of AOP infarcts are not diagnosed in the emergency setting. Timely diagnosis of an acute bilateral thalamic infarct can be challenging, and this case report highlights the uncommon neurological presentation of AOP infarction. The therapeutic time window to administer IV tPA can be missed due to this delay in diagnosis, resulting in poor clinical outcomes. To initiate appropriate acute ischemic stroke management, we propose a comprehensive radiological evaluation in the emergency room for patients with a high suspicion of an AOP infarction.