Mystery Case: Acute clot within P1 segment mimicking cisternal hemorrhage in Percheron infarction

Abstract

A 72-year-old man was admitted after sudden onset of coma (Glasgow Coma Scale score 6/15). At clinical examination he had tetraparesis, bilateral Babinski signs, bilateral unresponsive miosis, and vertical gaze palsy. Head CT scan demonstrated a linear hyperdensity outlining the interpeduncular cistern (figure, A). Additional MRI examination was performed promptly to rule out blood extravasation since thrombolysis was considered. Bilateral Percheron artery type II infarction was demonstrated on diffusion-weighted imaging (figure, B). Magnetic resonance (MR) angiogram demonstrated complete occlusion of right P1 segment (figure, C), the abnormal hyperintensity seen on CT image corresponding to the occluding fresh clot. Comparison of CT and MRI data appeared mandatory to reach an appropriate therapeutic option in this peculiar condition. Follow-up MR angiogram demonstrated complete recanalization (figure, D).