Non-ischemic Cerebral Enhancing (NICE) Lesions Following Endovascular Treatment of Intracranial Aneurysms: A Case Report

Non-ischemic cerebral enhancing (NICE) lesions are a rare complication following endovascular therapy (EVT) for intracranial aneurysms, presenting as delayed-onset enhancing lesions on MRI. While their pathophysiology remains unclear, NICE lesions can pose diagnostic challenges due to their resemblance to neoplastic or infectious processes. We report a case of a 67-year-old female with incidental anterior communicating artery (ACom) and posterior inferior cerebellar artery (PICA) aneurysms treated with EVT using a flow diverter for the PICA aneurysm and stent-assisted coiling for the ACom aneurysm. Three months post procedure, a follow-up MRI revealed punctate, nodular, and annular enhancing lesions with peri-lesional edema, consistent with NICE lesions. Despite these findings, the patient remained asymptomatic, reporting only subjective fatigue. She was treated with a one-month course of glucocorticosteroids, leading to symptom resolution. Serial MRI over one year demonstrated a reduction in edema, though new lesions appeared. This case underscores the importance of long-term imaging surveillance following EVT for cerebral aneurysms, as NICE lesions may persist, regress, or evolve over time. Although the clinical course may be benign in some patients, the presence of persistent or newly emerging lesions raises concerns regarding their underlying mechanisms and potential long-term impact. Further research is needed to better understand the pathophysiology, optimize management strategies, and refine follow-up protocols for patients with NICE lesions after EVT.