CASE PRESENTATION: A 79-year-old female with MM presented to the emergency department with acute AMS 24 hours after being discharged from the hospital. She had been successfully treated for sepsis secondary to multifocal pneumonia. At discharge, she was conversant, able to walk and follow commands appropriately. However, upon presentation 24 hours later, she was stuporous and had right gaze deviation with left sided facial droop. Vital signs were stable. She required intubation for airway protection and was admitted to the intensive care unit (ICU). While in the ICU, she exhibited intermittent gaze deviation from right to left. Computed Tomography and Magnetic Resonance Imaging of the brain and CXR were unremarkable. Laboratory data including CBC, CMP, urinalysis and cerebrospinal fluid analysis showed no evidence of infection, liver failure, hyperuricemia, hypercalcemia or hyperviscosity. A continuous 24-hour EEG was negative for seizures. Her ammonia (NH3) level was noted to be 177 mmol/L and she underwent emergent dialysis for 2 consecutive days. Post dialysis, NH3 levels decreased to 101-110 mmol/L. She became alert, followed simple commands and her neurologic deficits disappeared. However, once NH3 increased back to prior level within six hours of dialysis, she again became stuporous. Chemotherapy was not pursued in accordance with patient’s prior wishes. She expired ten days later.