[Diagnostic difficulties in differentiating of arteriovenous fistula -- case report]

Arteriovenous carotid-cavernous fistula is an abnormal connection between the dural branches of carotid artery or vertebral artery and the dural sinuses. Its clinical manifestations can resemble the crucial signs of thyroid orbitopathy, an inflammatory disorder of the orbit associated with Graves' disease. Therefore, differential diagnosis of thyroid orbitopathy and the congestion of the orbit seen in arteriovenous fistula is often clinically and radiologically confused. This is the case report of the simultaneous occurrence of dural arteriovenous fistula in 59 years old woman. The first manifestation was unilateral exophthalmia. After Computer Tomography and Magnetic Resonance Imaging were performed, the preliminary diagnosis of thyroid orbitopathy was established. The response of eye disorder to corticosteroid treatment resulted in evident deterioration. This prompted a reconsideration of the diagnosis and a new evaluation of the patient with sensitive techniques, leading to the final diagnosis of arteriovenous fistula.