A Case Presentation from Bascom Palmer Eye Institute Grand Rounds
by Dr. Andrea Kossler
Just to recap, in part I - 'A Sticky Situation', a 33-year-old female with right proptosis was discussed. She was found to have an orbital arteriovenous malformation. In part II we will briefly discuss AVMs as well as the management and outcome of our patient.
Arteriovenous malformations are high flow communications characterized by normal endothelial turnover within dysplastic, hypertrophied vessels. The connections are congenital and contain a vascular network between the artery and vein. Branches of the ICA and ECA usually supply them. These lesions are slowly progressive and can occur between the ages of 8 and 50. Orbital AVMs are rare and can be associated with retinal AVMs seen in a variant of Wyburn Mason Syndrome.
Signs and symptoms of orbital AVMs are congested conjunctiva, dilated corkscrew vessels, engorged retinal veins, an audible bruit, exophthalmos, limitation of EOMs, increased IOP and, in advanced cases, compressive optic neuropathy. AVMs can enlarge with hormonal changes, trauma, venous thrombosis or spontaneous hemorrhage, placing the optic nerve at greater risk for compression.
Diagnosis is made by angiography, MRA/MRI showing flow voids, and ultrasound showing enlarged EOMs and superior ophthalmic vein.
Traditional treatment is embolization followed by surgical resection if needed. N-butyl cyanoacrylate (NBCA) is usually the agent of choice. Embolization obliterates feeder vessels, sometimes leading to shrinkage of the lesion with no need for surgery. There are risks involved with this procedure, such as central retinal artery occlusion, but the ophthalmic artery can be embolized safely if done with extreme caution, taking care to embolize distal to the branch of the central retinal artery. When surgery is needed, it is ideally performed within a few days of the embolization to avoid the recruitment of new vessels.
Our patient was scheduled for embolization by neurosurgery. She first underwent 2 provocative tests prior to the embolization for safety. NBCA was used. Immediately after the injection of NBCA, the patient complained of vision loss. Her clinical exam revealed NLP od with a 4+ RAPD od. CRAO protocol was given without improvement. Her fundus photos are seen below.
OCT reveals thickening of the macula od. From the follow up exam it is evident that the cyanoacrylate glue went into the central retinal artery, into the branches and completely cut off blood supply to the macula and surrounding retinal tissues.
Extreme care was taken by the neurosurgeons, including 2 provocative tests prior to placement of the glue, yet this case shows that devastating results can still occur in the most careful and skilled hands.
The plan at this point is to monitor the patient closely for signs of ocular ischemia, NV or hypotony. She is to follow monocular precautions by wearing polycarbonate lenses. Surgical excision will be postponed at this time, but neurosurgery will consider a second embolization of collateral feeders in an attempt to reduce the size of the lesion so her eye will be less exposed.