The correct answer is E.
Explanation:
This patient most likely has a carotid cavernous fistula (CCF), which is an abnormal connection between the carotid arterial system and the cavernous sinus. This connection allows arterial blood to flow directly into the venous system, bypassing the normal capillary network. CCFs typically present with ophthalmic manifestations due to increased venous pressure. Typical symptoms include proptosis, conjunctival injection and chemosis, diplopia, increased IOP, arterialization of the conjunctival veins (tortuous and dilated vessels), visual loss in severe cases, pulsatile tinnitus, and headache. A majority of CCFs are caused by trauma or can also occur spontaneously. In our case, the patient’s craniotomy was the most likely etiology for her to develop a CCF. Our patient also presented with classic symptoms including dilated and tortuous veins, slight proptosis in the right eye, borderline high IOP OD, diplopia, and esotropia which support the diagnosis of a CCF. The gold standard test for diagnosing CCFs is digital subtraction angiography (DSA), which provides detailed and dynamic imaging of the vasculature and allows for precise localization and characterization of the fistula.
A) A carotid doppler ultrasound is useful for assessing blood flow in the carotid arteries but does not provide sufficient detail about the cavernous sinus or presence of a fistula.
B) CT of the head can identify signs of a CCF but lacks the detailed vascular imaging necessary for a definitive diagnosis. A CT angiogram would be more useful but not as definitive as a DSA.
C) Orbital ultrasound can show the effects of enlarged superior ophthalmic vein but does not offer detailed vascular imaging needed to diagnose a CCF. This is also helpful for visualizing orbital structures and determining recti muscle enlargement in thyroid eye disease. However, this patient is less likely to have TED because presentation is normally usually bilateral and a CCF is more likely in the setting of recent surgery.
D) A conjunctival swab test will not help diagnose a CCF and is not commonly used to diagnose conjunctivitis.
