Mycophenolate Mofetil–Associated Atypical Posterior Reversible Encephalopathy Syndrome With Anterior Circulation Involvement and Tetraparesis

Introduction: Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiologic entity characterized by acute neurologic symptoms and vasogenic edema on neuroimaging, classically involving the parieto-occipital regions. Atypical distributions and presentations can occur, particularly in the setting of immunosuppression. Case Presentation: We describe a 71-year-old woman with pulmonary sarcoidosis receiving chronic prednisone and mycophenolate mofetil who presented with acute altered mental status and sudden-onset tetraparesis after being found unresponsive at home (exact symptom duration prior to discovery was unclear). On arrival, her Glasgow Coma Scale (GCS) score was 6 (E2, V1, and M3) with abnormal flexion to painful stimuli and no purposeful voluntary movement; motor strength on the Medical Research Council (MRC) scale was 0/5 in all extremities. Noncontrast computed tomography (CT) of the head, CT angiography (CTA), and CT perfusion did not demonstrate hemorrhage, infarction, or large-vessel occlusion. Electroencephalography (EEG) showed diffuse slowing without epileptiform activity. Magnetic resonance imaging (MRI) demonstrated cortical and subcortical abnormalities in a frontal watershed distribution, consistent with an atypical PRES pattern involving the anterior circulation. Conclusion: Mycophenolate mofetil was discontinued, and prednisone was continued. Over the ensuing 2 weeks, her neurologic deficits gradually improved with rehabilitation; by Hospital Day 14, motor strength had improved from 0/5 to at least 3/5 in multiple muscle groups. This case highlights a rare presentation of PRES with predominant anterior circulation involvement and profound motor deficits, and it underscores the importance of considering mycophenolate mofetil as a potential precipitating factor.