[A case of NIDDM associated with oculomotor palsy due to atypical carotid cavernous sinus fistula].

Partial ophthalmoplegia due to third nerve palsy with an intact pupil is a frequent cause of diploplia observed in diabetic patients. Pupillary muscle involvement, such as anisocoria and loss of light reflex, is usually uncommon in this diabetic cranial mononeuropathy. A 65-year-old woman with non-insulin dependent diabetes mellitus (NIDDM) suddenly developed a severe headache and diplopla. Right oculomotor nerve palsy was observed in association with anisocoria, ptosis of the right lid, and a defective light reflex. No exophthalmos or vascular bruit was observed in the right orbital region. Computed tomography and magnetic resonance images of the head were negative. Cerebral angiography revealed a carotid cavernous sinus fistula (CCF). The patient was successfully treated with external carotid artery embolization combined with radiation. It is well known that pupil sparing in oculomotor nerve palsy predicts an extraaxial ischemic lesion, while pupil involvement predicts an extraaxial compression lesion. Therefore, pupillary involvement in oculomotor nerve palsy in diabetic patients necessitates cerebrovascular investigation to rule out ICPC aneurysm or tumor. In this circumstance, a variant type of CCF without characteristic ocular signs should be included in the differential diagnosis.