Posterior Reversible Encephalopathy Syndrome Associated With Severe Proton Pump Inhibitor-Induced Hypomagnesemia: A Rare Case.

Posterior reversible encephalopathy syndrome (PRES) is a potentially reversible cause of acute neurological deterioration. Hypertension is the most common trigger, but metabolic and drug-related causes must also be considered. We describe a patient who developed PRES with posterior circulation involvement in the absence of hypertension. The patient showed severe hypomagnesemia after prolonged proton pump inhibitor (PPI) use, where the onset of neurological symptoms occurred after the increase of esomeprazole (40 mg/day). Brain magnetic resonance imaging (MRI) showed PRES findings in the cerebellum, evolving into a gliotic lesion. Hypomagnesemia may promote endothelial dysfunction and vasogenic edema and has been increasingly linked to PRES. In patients with PRES and no clear trigger, serum magnesium should be monitored, especially in long-term PPI users. This case highlights a reversible and preventable cause of PRES, supporting the need to monitor serum magnesium and prescribe PPIs with caution in clinical practice.