Presentation
Decreased GCS, blown right pupil. Normal CT brain and CT angiogram.
Patient Data
Bilateral V-shaped symmetrical lesions involving the paramedian thalamus and midbrain with homogeneous diffusion restriction, high T2 and low T1. Mild associated mass effect without obstruction.
No susceptibility artifact to suggest associated hemorrhage.
Case Discussion
Classic appearance for infarct of the artery of Percheron - an anatomical variant with bilateral paramedian thalamus supply arising from a solitary branch of one of the posterior cerebral arteries.
Differentials for bilateral paramedian thalamic lesions with diffusion restriction include top of the basilar artery syndrome and internal cerebral vein thrombosis with venous infarct (usually less well-defined edema, more likely to hemorrhage and which would usually have associated changes in the deep cerebral veins). There are multiple other metabolic and infective causes of thalamic lesions (such as Japanese encephalitis and Wernicke's encephalopathy), although less likely with this appearance.
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