Fatal Contrast-Induced Encephalopathy with Malignant Cerebral Edema Following Intracranial Aneurysm Embolization Using a Low-Osmolar Contrast Agent: A Case Report

Background: Contrast-induced encephalopathy is an uncommon and typically reversible neurological complication following the administration of iodinated contrast media. However, severe and fatal outcomes, particularly those involving malignant cerebral edema, are rare. Most historical fatal cases were associated with older, hyperosmolar agents. The novelty of this case lies in demonstrating a rapid, irreversible, and fatal neurotoxic outcome following the use of a modern, low-osmolar, non-ionic contrast agent during a routine neurointerventional procedure. Case presentation: A 48-year-old female with hypertension was admitted for a secondary coil embolization of a recurrent right middle cerebral artery aneurysm. The procedure was completed using 200 mL of iopromide, a low-osmolar contrast medium. Post-procedure, the patient rapidly developed right ocular edema, left hemiparesis, and progressed to a coma. Computed tomography revealed diffuse right hemispheric edema and extensive subarachnoid enhancement, initially mimicking hemorrhage, but angiography showed no active bleeding or vessel occlusion. Despite supportive care including nimodipine, the patient's condition worsened due to progressing diffuse swelling. An emergency decompressive craniectomy was performed, which confirmed severe, pale brain swelling and cortical venous congestion without subarachnoid hemorrhage. Postoperatively, she developed refractory intracranial hypertension and died 20 days after the intervention. Conclusions: This case report demonstrates that even modern, low-osmolar, non-ionic contrast agents can induce irreversible, fatal contrast-induced encephalopathy complicated by malignant cerebral edema. This highlights a critical risk associated with neurointerventional procedures. Clinicians must maintain a high index of suspicion for this severe neurotoxicity, even when using newer contrast media. This case underscores the urgent need for improved risk stratification, early recognition, and effective neuroprotective strategies for high-risk patients undergoing such procedures.