Localized Contrast-Induced Encephalopathy of the Medulla Oblongata Following Endovascular Treatment of Posterior Circulation Lesions: A Report of Two Cases.

Contrast-induced encephalopathy (CIE) is a rare but serious complication of endovascular treatments. Contrast materials can disrupt the blood-brain barrier and subsequently cause encephalopathy. We herein report two cases. Case 1 is a 63-year-old woman presented with an unruptured right vertebral artery aneurysm. The patient underwent the stent-assisted coil embolization of the lesion and experienced dizziness, nystagmus, and numbness in the right upper limb after the procedure. T2-weighted images and fluid-attenuated inversion recovery sequence (FLAIR) images revealed a high-intensity lesion in the right lateral medulla oblongata. The lesion was thought to have vasogenic edema and was diagnosed as CIE. Case 2 is a 76-year-old man presented with severe basilar artery stenosis. The patient underwent percutaneous transluminal angioplasty and stenting of the basilar artery and experienced dizziness and dysarthria during the procedure. Computed tomography (CT) revealed a high-density lesion in the left lateral medulla oblongata. According to the water-iodine image of dual-energy CT, the lesion was thought to be a contrast leakage and was diagnosed as CIE. In the two cases, intravenous steroids improved the symptoms, and follow-up imaging revealed the disappearance of the lesions. Frequent injections, large amounts, low temperatures, and stagnation of the contrast material in the same vascular territory can induce encephalopathy. Patients with chronic kidney disease, hypertension, and lesions of the posterior circulation can be at risk of CIE.