TWO CASES OF DIPLOPIA CAUSED BY ARTERIOVENOUS FISTULAS AND A SHORT LITERATURE REVIEW

Abstract

Introduction: Dural arteriovenous fistulas (dAVFs) are vascular abnormalities involving abnormal connections between branches of the carotid or vertebral arteries and the dural leaflets of the venous sinuses. The most common location is the transverse–sigmoid sinus junction, although they may also occur in the cavernous sinus, in which case they are referred to as carotid–cavernous fistulas. Their clinical course depends mainly on the pattern of venous drainage.

Case presentation: We present two cases from our department who presented to the Emergency Department with several months’ history of diplopia. Clinical examination showed impaired abduction of the left eye, left eye proptosis and redness. The first patient had undergone imaging studies prior to admission and, in conjunction with the clinical findings, digital subtraction angiography (DSA) was deemed necessary, establishing the diagnosis of bilateral direct carotid–cavernous fistulas (Barrow type A). The second patient underwent brain and neck magnetic resonance imaging and angiography, which revealed multiple arteriovenous fistulas involving branches of the left external carotid artery and the ipsilateral internal jugular vein, with retrograde venous flow into the inferior petrosal sinus, the ipsilateral sigmoid sinus, the left superficial middle cerebral vein, the left inferior ophthalmic vein, as well as the left sigmoid and transverse sinuses (Cognard type IIa+b or Borden type II).

Conclusions: Cranial nerve palsy even in the absence of overt signs of venous congestion does not exclude the presence of an arteriovenous malformation of the central nervous system. When clinical findings suggest a possible vascular etiology, or when routine diagnostic work-up is inconclusive, appropriate imaging studies should be performed to ensure accurate diagnosis and optimal management.