Hyperammonemic Encephalopathy: A Unique Presentation of Multiple Myeloma

Multiple myeloma is a malignancy of plasma cells which are commonly found in the bone marrow. Known for causing a wide range of symptoms and affecting various organ systems, multiple myeloma is a rare malignancy with the entire pathophysiological process yet to be elucidated. We present a case of a 51-year-old male with a history of previously treated multiple myeloma in remission, initially presenting with chest pain with an unremarkable work-up. His hospital course was complicated by hyperammonemia causing encephalopathy requiring mechanical ventilation. After an extensive work-up to find an underlying cause, he was diagnosed with relapsing multiple myeloma. Due to a prolonged and complicated hospital course, the family pursued comfort measures and the patient passed away peacefully. Multiple myeloma induced hyperammonemic encephalopathy is a rare phenomenon carrying a high morbidity and mortality rate. Being still poorly understood, this manifestation of an already lethal diagnosis should be considered as a differential diagnosis of hyperammonemia. While early and aggressive treatment has shown some benefit and improved patient outcomes, further studies and understanding is needed to help diminish the mortality associated with hyperammonemic encephalopathy due to multiple myeloma.