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.