Introduction: Encephalopathies from 5 fluorouracil (5FU) are rare and generally resolve favorably.
Case: Six days after her first course of chemotherapy combining 5FU and cisplatin, a 45-year-old woman developed acute encephalopathy with altered consciousness and convulsions. MRI showed hyperintense signals of the white matter, mainly ventricular. Despite symptomatic treatment and thiamine perfusion in intensive care, the patient deteriorated and resuscitation failed. Blood tests confirmed 5FU toxicity.
Discussion: 5FU encephalopathies are rare and most often resolve favorably after treatment is stopped. Two pathophysiologic mechanisms may explain these encephalopathies: a deficit of dihydropyridine dehydrogenase, leading to an increased level of serum uracil with digestive and mucosal toxicity, or interaction of 5FU catabolites with various intracerebral metabolic pathways.