Simultaneous and Sequential Development of Sixth Nerve Palsy and Horner's Syndrome from Carotid Cavernous Sinus Fistulas

The combination of ipsilateral sixth nerve palsy (6NP) and Horner's syndrome (Horner's) is a localizing sign of an injury to the posterior cavernous sinus. The presentation and clinical course of 3 patients presenting with coexisting ipsilateral 6NP and Horner's as a result of carotid cavernous sinus fistulas (CCFs) are discussed in this case series. We highlight these cases to show the possible sequence of events: (i) simultaneous discovery of 6NP and Horner's, (ii) 6NP followed by Horner's, and (iii) Horner's followed by 6NP. It is important to carefully assess for Horner's in patients with 6NP as this has high localizing value. In patients with a red eye consistent with a CCF, identifying Horner's also has high localizing value and can confirm the suspicion of a CCF. Clinicians should recognize that although 6NP and Horner's localize to the cavernous sinus and may be due to a CCF, they may appear in isolation or sequentially. It is also important to understand that Horner's and 6NP have different prognoses: 6NP usually resolves over time, whereas Horner's tends to persist.