Delayed Neuroinflammation Mimicking Stroke After Flow-Diverting Stent Placement: A Case Report on Diagnostic and Therapeutic Challenges.

Flow-diverting stents are increasingly used in the management of complex intracranial aneurysms, offering superior occlusion rates compared to conventional techniques; however, rare complications such as neuroinflammation can mimic more common conditions like stroke, creating significant diagnostic challenges. We report a case of a 50-year-old woman with multiple intracranial aneurysms, hypertension, hypercholesterolaemia, and a prior stroke who underwent flow-diverting stent placement for a recurrent right posterior communicating artery aneurysm. Four weeks post procedure, she presented with severe headache, photophobia, neck stiffness, and unilateral weakness. Initial imaging suggested acute ischaemic stroke or metastatic disease, but serial MRI demonstrated a dynamic pattern of progressive and regressive lesions. Multidisciplinary evaluation ultimately identified neuroinflammation, specifically non-ischaemic cerebral enhancing (NICE) lesions, a rare stent-related complication. Treatment with corticosteroids led to marked clinical and radiological resolution. This case underscores the typical features of post-stent neuroinflammation, such as delayed onset, stroke-like symptoms, and steroid responsiveness, while highlighting its diagnostic complexity due to overlapping presentations with ischaemic events. It also suggests that prior interventions may confer increased risk, emphasising the importance of serial imaging and multidisciplinary collaboration in achieving accurate diagnosis and optimal patient outcomes.