MASLD-Induced Hyperammonemia With Atypical, Restricted Diffusion Pattern Suggesting Mixed Metabolic and Hypoxic-Anoxic Injury.

Background: Hepatic encephalopathy is a common cause of altered mental status for patients with decompensated cirrhosis. Their conditions typically improve with high-dose laxatives; if not optimally treated, can develop neurologic sequelae like cerebral edema and herniation. In severe cases, despite normal systemic oxygenation, hyperammonemia may result in mixed restricted diffusion patterns that partially resemble those seen in hypoxic-anoxic brain injury. Case Presentation: A 61-year-old woman with cirrhosis secondary to metabolic dysfunction-associated steatotic liver disease, scleroderma, and rheumatoid arthritis presented to the emergency room with altered mental status. She was admitted to the intensive care unit (ICU) and was intubated due to hepatic encephalopathy and acute blood loss anemia found to be esophagitis on esophagogastroduodenoscopy. After being downgraded to medical care, the patient was altered again and had an ammonia level of 450 μmol/L. The patient was minimally alert after an aggressive bowel regimen, had ammonia levels within normal limits on day 2 of ICU readmission, and was successfully extubated, which prompted further workup for her neurological status. A negative initial head computed tomography, and a subsequent magnetic resonance imaging (MRI) a few days later showed signs of restricted diffusion reported to be consistent with hypoxic-anoxic brain injury, which did not correlate with her hemodynamically stable vital signs throughout the hospital admission. These findings were reported as potentially related to metabolic abnormalities on repeat MRI which were not present at the time of the initial MRI. Conclusion: This case demonstrates a rare instance of neurologic and radiologic sequelae for a reported ammonia level of 450 μmol/L. Additionally, the rapidly down-trending ammonia levels with a standard bowel regimen and rectal tube suggest that the initial ammonia level may not have been as elevated. Neurologic imaging plays a key role in cirrhotic patients when metabolic correction fails to restore normal consciousness despite sometimes mixed and/or nonspecific restricted diffusion patterns.