Posterior-draining dural carotid cavernous fistulae: a possible cause of computed tomographic angiography negative isolated third nerve palsy

Computed tomographic angiography (CTA) is a well-established non-invasive investigation for this neurological presentation to exclude intracranial aneurysms. However, dural arteriovenous fistulae with anterograde venous drainage only can be missed by CTA. Here we reported two patients with painful complete third nerve palsy and dural carotid cavernous fistulae with anterograde venous drainage only missed by CTA. The natural history and management option are discussed. In patients with persistent symptoms or without vasculopathic risk factors, magnetic resonance angiography (MRA) or digital subtraction angiography (DSA) should be considered to exclude the diagnosis.