Contrast‑induced encephalopathy: An allergological point of view.

The intravascular administration of iodinated contrast agents (IC) can be associated with rare neurological complications such as contrast-induced encephalopathy (CIE). CIE has been primarily reported following cardiac and cerebrovascular angiographic procedures and after endovascular treatment of aneurysms. A 61-year-old woman with a history of breast cancer and recurrent respiratory infections presented with respiratory symptoms and persistent fever despite outpatient antibiotic therapy. A thoracic AngioCT with Iomeprol ruled out pulmonary thromboembolism, suggesting an infection. A few hours later, the patient developed acute confusion, behavioral changes, incoherent speech, and an erythematous rash on the trunk and proximal limbs. She was admitted to exclude ischemic, hemorrhagic, and infectious causes. A non-contrast cranial CT and lumbar puncture showed no significant findings. Other tests, including blood work, venous blood gas, and SARS-CoV-2 PCR, were normal. The patient improved spontaneously within 48 hours. A subsequent cerebral MRI with gadolinium showed no abnormalities. Given the likely association with contrast administration, the patient was referred to our Allergy Clinic. An allergological evaluation was performed, including patch and skin prick tests with Iohexol, Iodixanol, Iobitridol, Iomeprol, and Ioversol. All tests returned negative results at the 48- and 96-hour readings. The patient was discharged with a recommendation to avoid IC, except in very exceptional circumstances. CIE is a very rare, acute, and generally transient complication following the administration of IC. We highlight the importance of being aware of this adverse effect of IC, as it can lead to consultations with allergists.