Infratentorial-Predominant PRES with Respiratory Arrest Following Triple Vaccination

Infratentorial-predominant posterior reversible encephalopathy syndrome (IPPRES) is a rare PRES variant that mimics posterior circulation stroke. We report a 57-year-old normotensive female who developed thunderclap headache, visual disturbances, and respiratory arrest 2 hours after triple vaccination (COVID-19/influenza/pneumococcal). Initial CT suggested cerebellar infarction, but MRI confirmed bilateral vasogenic edema predominantly involving cerebellum and brainstem, consistent with IPPRES. We propose vaccine-induced immune activation may lower the hypertensive threshold for PRES. This case illustrates diagnostic challenges of IPPRES and the importance of recognizing brainstem compromise as a cause of respiratory deterioration.