An Unexpected Origin of Coma in a Patient with Atrial Fibrillation: Bilateral Paramedian Thalamic and Midbrain Stroke Secondary to Artery of Percheron Occlusion

The thalamus is a part of the arousal system; its infarction can lead to varying levels of impaired consciousness (from hypersomnia to coma). It is mainly supplied by small perforating arteries arising from the posterior cerebral artery (PCA). There are several variants of this vascularization, the artery of Percheron (AOP) is one of those variants which takes the form of a solitary arterial trunk that arises from one of the proximal segments of the PCA and bifurcates to supply both paramedian thalami. Its occlusion results in bilateral paramedian thalamic infarction with or without midbrain involvement. Clinical presentation is varied and non-specific, it usually presents with altered mental status, hypersomnolence and ocular motor disorders. We report a rare case of acute coma in a 71-year-old man with atrial fibrillation (AF) secondary to a bilateral thalamus stroke due to AOP occlusion. Early diagnosis is challenging as it is often missed on a conventional Computed Tomography (CT), diffuse-weighted magnetic resonance imaging (MRI) demonstrates the ischemic lesions after 48 hours. Antithrombotic drugs, supporting therapy, and rehabilitation were performed and patient’s mental status gradually improved.