Cavernous Sinus Dural Arteriovenous Fistula in a Patient with Thyroid-Associated Ophthalmopathy: Complete Resolution after Medical Treatment

Thyroid-associated ophthalmopathy (TAO) is a well-known and frequent epiphenomenon of a hyperthyroid autoimmune disease that can present with proptosis, strabismus, and diplopia. Ophthalmopathy can occur in the absence of overt Graves' disease, even in euthyroid patients. Cavernous sinus dural fistulas (CS-DAVF) are abnormal communications between the cavernous sinus (CS) and dural branches from internal carotid or external carotid arteries. They can often present with ocular symptoms that can mimic a thyroid-associated ophthalmopathy. CS-DAVF are usually successfully treated with an endovascular embolization that can be pursued both through a transvenous or transarterial approach. TAO and CS-DAVF can coexist especially when the ocular symptoms are unilateral. In those cases, an endovascular embolization is usually curative, but sometimes the procedure can fail. Our hypothesis is that some cases of CS-DAVF may be of secondary nature (i.e., caused by compression of the venous outlet by the hypertrophic ocular muscles); therefore, treating the ocular disease with medical therapy may solve the vascular problem as well. We present a case of a CS-DAVF in a patient with TAO successfully treated with sole medical therapy after the failure of a first-line endovascular treatment.