Sphenoid sinus mucocele causing third nerve paralysis: CT and MR findings.

A 64-year-old woman presented with a 2 week history of ptosis and medial-gaze paralysis of her left eye. Computed tomography scanning of the paranasal sinuses revealed an expansile, homogeneous lesion with no contrast enhancement in the sphenoid sinus. The mass was hyperintense on all MR sequences and there was extension of the mass to the left cavernous sinus and optic canal. Operation revealed a large mucocele. Third nerve palsy disappeared 4 weeks after operation. Because the spread of mucoceles is variable, they may cause different symptoms. Radiological evaluation, especially computed tomography and magnetic resonance imaging, are useful in diagnosis of mucoceles and help to explain the clinical symptoms by showing the spread of the lesion.