2026 American Academy of Neurology Abstract Website

Objective:

To describe a rare case of cerebral foreign body reaction (CFBR) following pipeline embolization.

Background:

Cerebral foreign body reaction (CFBR) is a rare and under recognized complication of neuro endovascular procedures, resulting from a granulomatous inflammatory response to hydrophilic polymer coatings on intravascular devices. CFBR can mimic stroke or CNS vasculitis, causing transient neurological deficits and multifocal infarcts. We report a 43 year old man who developed CFBR after pipeline embolization, presenting with cognitive decline.

Design/Methods:

Single case report and literature review.

Results:

A 43-year-old man with recent peri mesencephalic subarachnoid hemorrhage (SAH) underwent digital subtraction angiography (DSA), revealing an incidental left ICA carotid cave aneurysm, treated with a pipeline embolization device. He was discharged on dual antiplatelet therapy.

Four days later, he presented with syncope, slurred speech, confusion, lip numbness, and blurry vision. Cognitive testing revealed deficits in naming, attention, language, abstraction and delayed recall (MoCA 18/30). Brain MRI showed multifocal restricted diffusion along with vessel wall enhancement bilaterally, suggesting an inflammatory process. CSF analysis revealed lymphocytic mild pleocytosis.

Given the ongoing encephalopathy, recent endovascular intervention, imaging findings suggestive of CNS vasculitis, CFBR secondary to polymer coating was suspected. He received IV methylprednisolone 1 g daily for 3 days, followed by oral prednisone 80 mg daily with a prolonged taper. His cognitive function dramatically improved, with his MoCA score increasing from 18 to 27 at discharge. Follow up brain MRI at three months showed resolution of the inflammatory process and restricted diffusion.

Conclusions:

CFBR is a rare cause of secondary CNS vasculitis following pipeline embolization. Clinicians should suspect CFBR in patients with unexplained neurological decline. This case underscores the importance of early recognition and prompt initiation of corticosteroid therapy, which can lead to substantial clinical and radiographic recovery.