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Show T Journal of Nemo- Ophthalmology 20( 1): 17- 19, 2000. • 2000 Lippincott Williams & Wilkins, Inc., Philadelphia i Arteriovenous Communication in the Orbit • Angela W. Kim, MD, and Gregory S. Kosmorsky, DO i <> i ° Arteriovenous malformations ( AVMs) are anomalous communications between arterial and venous systems without interposed capillaries. These lesions are rarely entirely intraorbital. A case of an arteriovenous communication between branches of the internal and external carotid arterial circulations and the ophthalmic veins located within the orbit is reported. Treatment with embolization resulted in a branch retinal artery occlusion. Attempted direct arterial occlusion of a dural- based fistula of the eye is a risky procedure. If embolized, AVMs should probably be approached from the venous side, if at all. Key Words: Branch retinal artery occlusion- Embolization- Orbital arteriovenous malformation. Arteriovenous malformations ( AVMs) are anomalous communications between arterial and venous systems without interposed capillaries. They may be the result of anomalous differentiation or persistence of anastomotic vascular channels formed during embryogenesis. They may also arise or enlarge secondary to trauma. Typical clinical signs of a fistula include exophthalmos ( pulsatile or nonpulsatile), periorbital swelling, dilated conjunctival and episcleral vessels, secondary glaucoma, restricted motility, and evidence of optic nerve compromise. Pain and headaches are commonly associated. Rarely, these lesions may be entirely intraorbital. Orbital AVMs appear clinically similar to the far more common carotid cavernous fistula or dural cavernous fistula, as well as to any other vascular abnormalities, either within the orbit or with increased flow transmitted to the orbit. Orbital sonography, color doppler flow imaging ( 1), radiographic imaging, and angiography are used to distinguish the lesion. Treatment modalities include embolization and surgical ligation or extirpation, with or without embolization. Complete treatment with embolization may be difficult because of poor accessibility, complexity of collateral pathways ( 2), and a somewhat unpredictable final destination of embolized particles ( 3). Attempts of complete treatment with embolization may result in damage to vital visual structures ( 2). We report a Manuscript received September 15, 1999; accepted October 7, 1999. From the Cole Eye Institute, Cleveland Clinic Division of Ophthalmology, Cleveland, Ohio. Address correspondence to Gregory S. Kosmorsky, DO, A31- Division of Ophthalmology, 9500 Euclid Avenue, Cleveland, OH 44195- 5024. case of embolization of an orbital AVM that resulted in a branch retinal artery occlusion. This was followed by the development of an ischemic central retinal vein occlusion with macular edema, resulting in a final visual acuity of 20/ 400. CASE REPORT In November 1990, a 65- year- old white man with a history of coronary artery disease, diabetes mellitus, and sinusitis presented with diplopia and chronic injection of his right eye. He had undergone coronary artery bypass grafting at an outside institution in February 1990, and postoperatively he experienced progressive redness of the right eye and binocular diplopia. Results of magnetic resonance imaging revealed significant pansinusitis, for which he underwent right- sided surgical drainage, with no improvement of his eye condition. In retrospect, results of the magnetic resonance imaging also revealed an enlarged superior ophthalmic vein in the right orbit. He was referred by an outside ophthalmologist, with the presumed diagnosis of a dural cavernous sinus dural shunt involving the right orbit. At the time of examination in November 1990, the patient had progressive swelling around the right eye, intolerable pain radiating from the eye to the neck and head, and a bruit. The neuro- ophthalmologic examination revealed visual acuities of 20/ 30 OD and 20/ 20 OS. There was no relative afferent pupillary defect. Hertel measurements with a base of 96 mm were 22 mm OD and 17 mm OS. There was a - 2 limitation of abduction, elevation, and depression and a - 1 limitation of adduction OD; there was full motility OS. Ishihara color plate testing was normal OU. Tonometry results revealed intraocular pressures of 26 mm Hg OD and 14 mm Hg OS. Cranial nerve function of V l - 3 was intact bilaterally. There were no audible bruits. Slit- lamp biomicroscopy OD showed upper and lower eyelid edema, 4+ dilated bulbar and episcleral conjunctival vessels to the limbus with chemosis, extensive rubeosis iridis, and a deep anterior chamber with 1/ 2+ cell and 3+ flare. On dilated fundoscopic examination, the cup- to- disc ratio was 0.4 OU, and in the right eye, there was 3+ venous engorgement with dot hemorrhages in the temporal macula. The patient was clinically diagnosed with a carotid cavernous fistula ver- 17 18 A. W. KIM AND G. S. KOSMORSKY FIG. 1. Enlargement of the superior ophthalmic vein in the right orbit ( arrow). sus a dural cavernous fistula with ocular ischemic syndrome. Examination of the left eye was unremarkable. The patient was placed on timolol 0.5%, 1 drop twice a day, OD. Results of an orbital magnetic resonance image revealed right- sided globe proptosis, prominent enlargement of all extraocular muscles, and diffuse enlargement of the superior ophthalmic vein; the cavernous sinus appeared symmetric, with normal enhancement with gadolinium ( Fig. 1). There was no evidence of a retro-orbital, juxtasellar, intraconal, or extraconal mass lesion. The globes and optic nerves appeared normal. Selective right internal carotid angiography showed ethmoidal branches arising from the ophthalmic artery, filling the superior ophthalmic vein and the confluence of the superior and inferior ophthalmic veins with retrograde venous filling. Selective right external carotid angiography showed the anterior deep temporal artery arising from the internal maxillary artery, filling the superior ophthalmic vein within the orbit with retrograde venous drainage. There was no evidence of abnormal communication or cross filling on selective vertebral angiography, and at no time could opacification of the cavernous sinuses, consistent with a dural cavernous fistula, be demonstrated. In November 1990, the patient underwent successful embolization of the right internal maxillary artery with polyvinyl alcohol particles. Attempts to catheterize the superior ophthalmic vein from the cavernous sinus were unsuccessful, leaving a persistent internal carotid arterial supply of the orbital fistula. The patient was instructed to perform right carotid compression therapy. The patient returned the following month, stating that the swelling and pain had decreased markedly. Trans-femoral catheterization showed rapid filling of the superior and inferior ophthalmic veins at their confluence, with retrograde flow to the orbital margins. This was fed primarily by branches of the right ophthalmic artery. There was no direct communication between the anterior portion of the right cavernous sinus and the confluence of the superior and inferior ophthalmic veins. Repeated attempts to catheterize the orbital veins through both the right cavernous sinus and the right external jugular vein via the angular vein were unsuccessful. Treatment via cut down of the superior ophthalmic vein was recommended. Direct embolization via a microcatheter placed in the ophthalmic artery was attempted at an outside institution ( Figs. 2 A and 2B). Intraoperatively, the patient experienced the acute onset of painless decreased vision in the right eye. He did not experience a hypertensive episode during the procedure. The following day, a neuro-ophthalmologist diagnosed a superotemporal branch retinal artery occlusion, with visual acuity of 20/ 40- 2 OD and an inferior arcuate defect. No emboli were seen. The patient had developed a relative afferent pupillary defect OD and had minimally higher intraocular pressures in the right eye compared with the left. Motility and proptosis improved, but 2 years after arterial embolization, he developed an ischemic central retinal vein occlusion with macular edema in the right eye that was believed to be secondary to his longstanding hypertension, rather than to the orbital fistula. He received panretinal photocoagulation for neovascularization of the angle. Final visual acuities were 20/ 400 OD and 20/ 20 OS. The relative afferent pupillary defect, dilated episcleral vessels, iris neovascularization, and macular edema persisted; intraocular pressures were stable at 21 mm Hg OD and 20 mm Hg OS, with the patient on no medica- FIG. 2A. Selective right carotid arteriography demonstrates the fistula ( small arrow). There is no communication with the cavernous sinus ( large arrow). B: Arteriogram of selective catheterization of the right ophthalmic artery: f, fistula; p, posterior ciliary artery; a, anastomotic vessels to extraocular muscles; I, lacrimal artery; m, medial nasal ophthalmic artery. J Neuro- Ophlhalmol, Vol. 20, No. I, 2000 ' I I ARTERIOVENOUS COMMUNICATION IN THE ORBIT 19 tions. Follow- up examinations were unable to be obtained. DISCUSSION We have described a patient with an orbital AVM who was treated with embolization. Vision was permanently compromised by a branch retinal arterial occlusion, a direct consequence of treatment. An ischemic central retinal vein occlusion 2 years after treatment resulted in a final visual acuity of 20/ 400. We suspected chronic hypertension as the most likely explanation for the venous occlusion, but we could not rule out abnormal venous dynamics as a contributing factor. Complications of endovascular management of orbital arteriovenous malformations include inadvertent central retinal artery embolization, dislodgement and migration of embolized material, and vasospasm secondary to catheterization. Goldberg et al. ( 4) described a patient who developed multiple branch retinal artery occlusions following postembolization orbital surgical excision, presumably because of migration of previously embolized particles. Another patient suffered vasospasm of the ophthalmic artery during catheterization, which was accompanied by decreased vision and a trace relative afferent pupillary defect ( 4). In both of their cases, there was improvement of the relatively transient visual deficits. Intraorbital AVMs are rare and may simulate a dural cavernous or carotid cavernous fistula. Shared symptoms and signs of these lesions would be expected to make differentiation difficult. Lesions situated within the orbit are less accessible and present a greater therapeutic challenge because of the co- existence of vital visual structures. In the case of embolization, evocative testing with amobarbital or lidocaine ( 5) to determine arterial pathways may help to avoid the morbidity of a central or branch retinal artery occlusion. Attempted direct arterial occlusion of a dural- based fistula of the eye is a risky procedure. If these rare lesions are to be treated by endovascular techniques, they should probably be approached by embolization from the venous side and not from the arterial side. REFERENCES 1. Erickson SJ, Hendrix LE, Massaro BM, et al. Color doppler flow imaging of the normal and abnormal orbit. Radiology 1989; 173: 511- 6. 2. Rootman J, Kao SCS, Graeb, DA. Multidisciplinary approaches to complicated vascular lesions of the orbit. Ophthalmology 1992; 99: 1440- 6. 3. Gross ND, Hornblass A, Ligation of an arteriovenous malformation with the Heifetz clamp. Arch Ophthalmol 1989; 107: 171. 4. Goldberg RA, Garcia GH, Duckwiler GR. Combined embolization and surgical treatment of arteriovenous malformation of the orbit. Am J Ophthalmol 1993; 116: 17- 25. 5. Horton JA, Dawson RC. Retinal Wada test. Am J Neuroradiol 1988; 9: 1167- 8. >> J Neuro- Ophthalmol, Vol. 20, No. 1, 2000 |