P3.M244: Beyond the Bulge: An Unusual Case of Proptosis in an Infant

Introduction: Unilateral proptosis in children has a broad differential diagnosis that includes infectious, vascular, inflammatory, and neoplastic etiologies. Obtaining a thorough history and physical exam is crucial to differentiating among these. Carotid-cavernous fistulas (CCF) are a rare cause of proptosis. Given its propensity for quick progression resulting in vision loss and neurologic sequelae, prompt recognition and treatment are critical.

Case Description: A 3 month old former full term female with a history of ASD and VSD presented to her pediatrician due to left eye enlargement and redness over several weeks. There was no eye discharge, fevers, congestion, abnormal ocular movements, or history of trauma. She was meeting her developmental milestones. Physical exam was notable for left eye proptosis with pupils equal, round, and reactive to light bilaterally, intact red reflexes, and normal eye gaze. Evaluation by ophthalmology did not reveal any increased intraocular pressure or retina changes.

MRI brain and orbits revealed findings consistent with left sided carotid-cavernous fistula with arterial feeders from the cavernous left internal carotid artery. In addition to the left sided proptosis, asymmetric enlargement of the extraocular muscles and dilatation of multiple communicating veins with the cavernous sinus including the left superior and inferior ophthalmic veins, left sphenoparietal sinus, and a massively dilated and tortuous left superior petrosal sinus were noted. Diagnostic cerebral arteriogram demonstrated left superior cerebellar arteriovenous malformation (AVM). Treatment with embolization is planned for a future date.

Discussion: A CCF is an abnormal connection between the carotid artery and the cavernous sinus. These are rare and constitute about 0.3 to 1.4% of all intracranial aneurysms. Though they can occur spontaneously, they occur more frequently following trauma, especially basilar skull fractures. The most common symptoms include proptosis, conjunctival injection, ocular pain, vision impairment, and ocular bruit. MRI and/or CT brain are often performed as first line diagnostic studies in patient with proptosis. However, cerebral angiogram is the gold standard for diagnosis of a CCF. Complications of intraorbital CCF’s include diplopia, cranial nerve palsies, glaucoma, and intraorbital hemorrhage resulting in orbital compartment syndrome which can lead to vision loss within a couple of hours if not promptly treated. Treatment is not without risk and therefore, assessing the impact of the CCF on a patient’s vision is an important consideration. Treatment options include endovascular embolization, stereotactic radiosurgery, and microsurgical removal of the nidus of the AVM.

Conclusion: A CCF is a rare cause of proptosis in children. The combination of proptosis, conjunctival injection, and ocular bruit, especially in the setting of recent head trauma or connective tissue disorders, should heighten suspicion for a CCF. Prompt recognition is vital to preserve vision and prevent complications that may result from increased intraocular pressure secondary to significant intracranial venous drainage.