Posterior Reversible Encephalopathy Syndrome in the Context of Phentermine Use Resulting in Intracranial Hemorrhage

Introduction: Posterior reversible encephalopathy syndrome (PRES) is a brain disorder characterized by clinical symptoms of headache, visual changes, altered mentation, and seizures. On neuroimaging, focal regions of symmetrical hemispheric edema are most commonly seen in the occipital lobes. It has been suggested that associated intracranial hemorrhage is present in approximately 5% to 17% of cases. We report a case of PRES with large bilateral parieto-occipital hemorrhages in the context of phentermine use. To our knowledge, this is the first reported case of phentermine use associated with PRES. Case Report: A 35-year-old woman taking phentermine for weight loss presented with altered mental status and 2 witnessed generalized seizures. She was found to have large bilateral parieto-occipital hemorrhages. The radiographic imaging was consistent with PRES with hemorrhagic conversion. After treatment with anti-epileptic medication, normalization of blood pressure, and discontinuation of phentermine, the patient improved clinically. Five months after the event, the patient had a repeat brain magnetic resonance imaging that showed resolution of the diffuse edema and hemorrhage. Conclusions: This case of PRES with hemorrhagic conversation is distinctive in the bilateral and extensive nature of the hemorrhage, and, to our knowledge, is the first reported case of phentermine use likely resulting in PRES. Physicians should be aware of the cerebrovascular risks associated with phentermine use.