Isolated painful abducens nerve palsy as a presentation of indirect carotid-cavernous fistula

Abstract

Indirect carotid-cavernous fistula (CCF) is a low-flow, vascular condition that may present with subtle and easily overlooked clinical features, sometimes resembling more common diagnosis such as microvascular neuropathy. We describe a 40-year-old man with poorly controlled diabetes and an active smoker, who presented with progressive left retrobulbar pain and binocular horizontal diplopia. Examination revealed an isolated left eye abduction limitation with the presence of mild corkscrew conjunctival vessels on the affected eye. Magnetic resonance imaging and angiography demonstrated bilateral distal internal carotid artery stenosis without an aneurysm. Digital subtraction angiography confirmed a left indirect CCF. The patient experienced early symptomatic improvement after angiography and was managed conservatively with near-complete resolution. This case highlights the importance of recognising subtle clinical signs and considering vascular causes in patients presenting with atypical cranial nerve palsies.