Isolated Unilateral Proptosis as a Heralding Feature of Ipsilateral Temporal Dural Arteriovenous Fistula

Dural arteriovenous fistulas (dAVFs) are rare intracranial vascular abnormalities that may present with varied and sometimes atypical clinical features. While proptosis is commonly associated with anterior cranial or cavernous sinus fistulas, it is unusual in posterior fossa dAVFs. We present the case of a 41-year-old man with progressive redness, swelling, and protrusion of the left eye over six months, without associated pain, diplopia, headache, or cranial nerve deficits. Ocular examination revealed preserved visual acuity and extraocular movements, with normal fundus findings. An initial diagnosis of a cavernous sinus fistula was considered. However, brain MRI with time-of-flight sequences revealed a left temporal dAVF with feeders from the external carotid artery and drainage into the vein of Labbé and transverse sinus, with a possible connection to the superior division of the middle cerebral artery. On clinical re-examination, a bruit was noted in the left occipitotemporal region. Doppler and transcranial Doppler studies confirmed mixed arterial and venous flow. The patient was referred for digital subtraction angiography and embolization. The symptoms of dAVFs vary depending on the shunt characteristics, location, and venous drainage pattern. Ocular signs are uncommon in noncavernous dAVFs. In this case, venous reflux through the vein of Labbé may explain the isolated proptosis. Management is guided by angioarchitecture and associated risk features, with high-risk fistulas requiring timely intervention. This case highlights the need to consider cranial dural AVFs in the differential diagnosis of isolated proptosis, as timely diagnosis and treatment are crucial.