Hyperammonemia-induced impaired consciousness following mFOLFOX6 therapy in a patient with recurrent rectal cancer.

Objectives FOLFOX is a standard chemotherapy regimen used to treat colorectal cancer. Adverse events associated with FOLFOX treatment include peripheral neuropathy and myelosuppression. This report discusses the case of a 64-year-old man with rectal cancer who developed hyperammonemia and impaired consciousness following initiation of mFOLFOX6 as a postoperative adjuvant therapy. Methods This case study reports on the clinical disease progression of the aforementioned patient. Results Following preoperative chemoradiotherapy, the patient underwent low anterior resection for rectal cancer. mFOLFOX6 was then initiated as postoperative adjuvant therapy. During the 5th cycle of mFOLFOX6 treatment, the patient presented with impaired consciousness and upper extremity convulsions. Blood testing revealed marked hyperammonemia (349 µg/dL (normal range: 12 - 66 µg/dL)). Imaging did not reveal any intracranial lesions that could cause impaired consciousness. The patient recovered within a day after rehydration and BCAA substitution. Conclusion Although impaired consciousness is a rare adverse reaction of FOLFOX, it has a major psychological impact on the patient and his/her family. Hyperammonemia should therefore be considered a potential cause of impaired consciousness during FOLFOX therapy and should be appropriately diagnosed and treated.