Woman presents with subacute diplopia, conjunctival injection and periorbital edema
The patient developed several symptoms over the previous 3 months, including ear and cheek pain, lightheadedness and vertigo.
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A 53-year-old first-grade teacher was referred by an outside ophthalmologist for evaluation of diplopia and headaches.
Three months before presentation, she felt congestion in both ears that she attributed to sinus disease. One month later, she noticed bilateral eyelid swelling that was worse in the morning and improved throughout the day, associated with increased injection of both eyes. One month before presentation, she developed pain in her cheeks and ears and was treated with antibiotics for presumed sinus disease without effect. Two weeks before presentation, she experienced acute onset of diplopia with lightheadedness and vertigo while driving.
Images: Lee GD, Hedges TR
The patient was evaluated by an otolaryngologist, who determined she did not have sinusitis, and referred her to an ophthalmologist, who ordered an MRI of the brain. This revealed a pituitary adenoma, and she was referred for neuro-ophthalmic consultation (Figure 1). She had no history of any chronic medical problems and did not take any medications. Her surgical, family and social histories were unremarkable.
Examination
At the time of our evaluation, the patient’s best corrected visual acuity was 20/25 in each eye. Pupils were normal without an afferent pupillary defect. Automated Humphrey visual fields were full in both eyes. Color vision was slightly diminished in both eyes. There was a 50% reduction in abduction of the left eye and full movements of the right eye. IOPs were 26 mm Hg in the right eye and 21 mm Hg in the left. There was edema of her upper and lower lids bilaterally as well as bilateral conjunctival injection with episcleral engorgement (Figure 2). She had no evidence of intraocular inflammation. Funduscopic examination showed sharp optic discs bilaterally and cup-to-disc ratios of 0.2.
What is your diagnosis?
Subacute diplopia
The differential diagnosis of subacute onset of a sixth cranial nerve palsy in a middle-aged woman includes ischemic cranial neuropathy, intracranial or intraorbital mass, intracranial aneurysm, cavernous sinus thrombosis or obstruction, pituitary apoplexy, carotid-cavernous fistula, myasthenia gravis, thyroid eye disease, varicella zoster, sarcoidosis, tuberculosis and Tolosa-Hunt syndrome.
Intraorbital mass and thyroid eye disease were ruled out by the MRI. Pituitary apoplexy would be unlikely given normal extraocular movements in the right eye, absence of an optic neuropathy and subacute presentation. Given elevated IOP, conjunctival injection and periorbital edema, there was high concern for a cavernous sinus dural shunt resulting in venous congestion. The longevity of symptoms pointed away from pituitary apoplexy, cranial nerve ischemia, and infectious or inflammatory causes.
After evaluation, the patient underwent an MRI/MRV of the brain and was started on IOP-lowering drops. Imaging showed the known pituitary lesion with heterogeneous density. However, it also revealed bilateral enlargement of the superior ophthalmic veins, which further suggested either cavernous sinus thrombosis or “arterialization” of the cavernous sinus secondary to a carotid-cavernous fistula (Figure 3). No cavernous sinus thrombosis was identified on MRV. Given concern for a carotid-cavernous fistula, cerebral angiography was performed and did indeed reveal dural carotid-cavernous fistulas bilaterally. Laboratory tests revealed panhypopituitarism secondary to the pituitary adenoma, which was determined to be unrelated to the ophthalmoplegia.
Discussion
A carotid-cavernous fistula (CCF) is an abnormal communication between the carotid artery and the cavernous sinus. It can be categorized as a direct fistula or a dural shunt.
Direct CCFs are high-flow vascular connections between the carotid artery and the cavernous sinus. They often occur as a result of head trauma or aneurysm rupture, with rapid progression of symptoms including visual loss, proptosis, lid swelling, orbital bruit and/or diplopia as a result of cranial nerve palsies. The fistula transmits arterial pressures into the low-pressure cavernous sinus, causing “arterialization” of the venous system and resulting in compressive neuropathies, venous congestion and even central retinal vein occlusion. Direct CCFs always require treatment by an interventional neuroradiologist or neurosurgeon.
Dural shunts, or dural carotid-cavernous fistulas, are low-flow communications involving small meningeal branches of the carotid system and the cavernous sinus. They are more indolent and can be related to systemic hypertension, pregnancy, sinusitis or mild head trauma. Clinical findings typically are related to venous congestion due to the transmission of higher arterial pressures into the cavernous sinus, although to a lesser degree than a direct fistula. Oftentimes, the superior ophthalmic veins are enlarged on MRI, as in this case. In a retrospective study of 27 patients, the most common clinical symptoms of dural carotid-cavernous fistulas were diplopia (45%), conjunctival injection (41%), chemosis (37%), proptosis (37%) and visual loss (30%). Other symptoms include eyelid edema or congestion, elevated IOP and dilated retinal vessels.
Close follow-up and co-management with neurosurgical colleagues are recommended. Dural CCFs are only treated if symptoms are intractable or if vision is threatened. Up to 50% of dural CCFs have been reported to close spontaneously. However, depending on the anatomic location of the arteriovenous connection, some dural CCFs may predispose the patient to cerebral infarction if they result in elevated intracranial venous pressure. These cases may warrant earlier intervention.
Various methods of treatment have been successful with transarterial and transvenous approaches including coils, balloons and liquid embolization agents. Closure rates have been reported to be between 85% and 99% for direct CCFs and between 70% and 78% for dural CCFs. As with any embolization procedure, complications may occur and include loss of vision or worsening of cranial nerve palsy.
Conclusion
Our patient underwent platinum coiling on the left side on the same day as her initial angiogram. The next day, her IOP had normalized, and there was resolution of the injection and periorbital edema on the left side. The right side was similarly treated soon after. One month later, the diplopia had improved significantly, the edema and injection had resolved bilaterally, and IOP was normal bilaterally (Figure 4).