A case of type 2 diabetes mellitus with a carotid-cavernous sinus fistula that required differentiation from diabetic mononeuropathy (oculomotor palsy)

A 66-year-old type 2 diabetic man had been treated with oral hypoglycemic agents since 1991. In 2003, he was introduced to our hospital, and insulin therapy with sulfonylurea was started. The recent HbA1c levels ranged between 6 % and 7 %. In January 2011, he complained of diplopia, left ocular pain, ptosis and a disturbance of eye movement. Following examinations by an ophthalmologist and neurosurgeon using MRI, he was diagnosed with diabetic mononeuropathy (left oculomotor palsy) and prescribed beraprost. Three months later, the diplopia, left ocular ptosis and disturbance of eye movement induced by the oculomotor palsy improved. However, the left ocular pain persisted, and treatment with pregabalin and carbamazepine was prescribed. Despite receiving this therapy, the patient's pain worsened, and repeat MRI was performed. The cavernous sinus was visualized and found to have a carotid-cavernous sinus fistula on MRA, and his symptoms improved after performing endovascular treatment. This is a rare caseoftype 2 diabetes complicated by a carotid-cavernous sinus fistula that required differentiation from diabetic mononeuropathy (oculomotor palsy).