Rapidly progressive visual impairment and internal carotid artery stenosis caused by sphenoid sinus mucocele: illustrative case.

This case illustrates that sphenoid sinus mucocele can lead to rapid progression of neurological deficits and ICA stenosis. Diagnosis based on imaging only may be challenging; however, timely recognition and prompt surgical intervention are crucial, as simple cyst fenestration can achieve complete neurological recovery and prevent severe major artery stenosis. https://thejns.org/doi/10.3171/CASE25932.