Abstract
BACKGROUND: Sphenoid sinus mucocele is a rare type of paranasal sinus lesions that can occasionally cause neurological deficits such as optic and oculomotor nerve deficits. However, internal carotid artery (ICA) stenosis associated with sphenoid sinus mucocele is extremely uncommon. OBSERVATIONS: A 36-year-old man with a history of craniotomy for Rathke's cleft cyst in childhood presented with rapidly progressive right-sided retro-orbital pain, ptosis, and diplopia. CT and MRI revealed a cystic lesion occupying the sphenoid sinus with adjacent ICA stenosis that markedly worsened within 4 days. Emergency endoscopic transnasal cyst fenestration was performed, and the mucinous contents were evacuated. The cyst wall adhered tightly to the dura of the sella turcica and the wall of the ICA. Postoperatively, the patient's visual and oculomotor nerve deficits resolved, and follow-up imaging demonstrated rapid improvement of the ICA stenosis. LESSONS: 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.