Occlusion of a vascular variant known as the Artery of Percheron results in bilateral paramedian thalamic infarcts with or without midbrain involvement. The most common cause is cardioembolism. This type of infarct has a favorable prognosis.

From the manuscript

Bilateral thalamic infarcts due to occlusion of the Artery of Percheron and discussion of the differential diagnosis of bilateral thalamic lesions

Abstract
The Artery of Percheron is a rare vascular variant in which a single dominant thalamoperforating artery arises from one P1 segment and bifurcates to supply both paramedian thalami. Occlusion of this uncommon vessel results in a characteristic pattern of bilateral paramedian thalamic infarcts with or without mesencephalic infarctions. We report a case of a 31-year-old man with acute bilateral thalamic infarcts and a truncated Artery of Percheron demonstrated on magnetic resonance angiography (MRA). Occlusion of the vessel was presumably due to embolism from a patent foramen ovale that was subsequently closed. The case presentation is followed by a discussion of bilateral paramedian thalamic infarcts including the causes and clinical presentation. The differential diagnosis of vascular and nonvascular etiologies of bilateral thalamic lesions is also discussed.