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Show ]. Clin. Neuro-ophth.1JmoJ. 2: 30 -42, 1%2. Doppler Sonography in the Diagnosis of Dural Carotidcavernous Fistula JAMES A. RUSH, M.D. WILLIAM M. BLACKSHEAR, JR., M.D. W. SANDERSON GRIZZARD, M.D. Abstract Intracranial dural fistulas in the region of the cavernous sinus usually occur in middle-aged or elderly women in whom physical findings of ocular pulsation, orbital bruit, and ocular injection are subtle or absent. We examined a 19-year-old man with hemophilia who had a red, mildly proptosed left eye. Typical features of a carotidcavernous sinus fistula were absent except for the presence of dilated, tortuous episcleral vessels. Directional Doppler ultrasound evaluation detected retrograde blood flow in the left frontal vein and thus confirmed the presence of an arteriovenous shunt. After a selective internal carotid angiogram demonstrated a shunt from a dural branch of the internal carotid artery, the patient's symptoms remitted spontaneously. Directional Doppler ultrasonography is a noninvasive test that can detect the presence of a low flow, retrobulbar arteriovenous shunt in the region of the cavernous sinus. Introduction Ophthalmologists have employed conventional Doppler ultrasound techniques for evaluating patients with carotid artery disease,l and for detecting orbital bruits in patients suspected of having a vascular orbital lesion. l We recently have used continuous wave bidirectional Doppler sonography* to help diagnose an intracranial arteriovenous fistula in a patient with mild ocular injection and proptosis. A low-flow shunt from the inferior cavernous sinus artery was identified by selective internal carotid arteriography. The Doppler technique is a sensitive, noninvasive diagnostic tool From the Departments of Ophthalmology (JAR. WSGj, and Surgery (WMB), University of South Florida College of Medicine. • Medasonics D-9 bidirectional Doppler with P-92A bidirectional probe. March 1982 that is useful in the evaluation of patients suspected of having a low-flow arteriovenous shunt in the region of the cavernous sinus. Materials and Methods In 1970, Brockenbrough demonstrated the clinical value of Doppler ophthalmic ultrasound in the diagnosis of stenosis or occlusion of the cervical internal carotid artery.l Ultrasonic methods of diagnosis depend upon the Doppler principle. When a high frequency ultrasound beam from a Dopplersending crystal strikes moving red blood cells, a proportion of the sound beam is reflected back and able to be detected by a receiving crystal. The frequency of the reflected signal is shifted above or below the base frequency according to direction of flow of the red blood cells. Blood flow towards a receiving crystal produces a higher frequency shift, and flow away from the probe produces a lower frequency sound beam. This is the Doppler effect. Although the Doppler-shifted frequency is small in magnitude compared with the base signal. it can be evaluated audibly or by a chart recorder (Fig. 1). Brockenbrough's supraorbital ophthalmic examination techniques made use of the presence of periorbital collateral vessels between the internal and external carotid circulations. He found that a reversal of the direction of blood flow in the frontal artery indicated high grade internal carotid artery stenosis or occlusion. We measured venous signals in the periorbital region of our patient. In the normal person, .uterial signals are e.lsily differentiated from venous signals because of their different flow directions and Doppler characteristics. Arteri.l1 signals vary directly with the cardiac cycle, whereas venous signals, which are much lower in velocity (frequency). vary with the respiratory cycle and are weakly audible. The supraorbital and frontal veins are accessible for study (Fig. 2) in patients who have an arterial venous fistula. In these patients, the valveless orbital veins now carrying arterial blood contain a 39 Doppler Sonography Figure 1. Medasonics 0-9 bidirectional Doppler unit with pencil probe. chart recorder. and foot pedal. /fron n Fi~ure ~. Pr(,bt.' (\Hlt.lInll\~ the ~('ndln~ l-lnd rc"(t"'lv,n~ pl('z(lel{'(trh: .. rv~t.ll, ...\1\ dl'h,..-l ('nh.lnu..d. U'd'fcded Vl"lh'U~ 5ign.lb when r()~i· IIPIH,d lIVl'r till' bfl)\,\,. A dl.\~r.Hllln.\tll rl'pTl'senl.ltillll llf .l dural shunt I~ ~.J\l)\\'1\ .,t the .Hrll\\' ",lll'H' Jrtcri.ll bll1lld with veOllU5 blood '$ Jepld('J !l\)\\,lng tnhl the l·.lVl·rrh,lll~ sinus. 40 Journal of Clinical Neuro-ophthalmology Rush, Blackshear, Grizzard much higher velocity signal th,m norm.l\. Additionally, venous blood flow is redirected out of the orbit. A pencil probe with recording device pl.K('d over the supraorbital or frontal vein locates the abnormal venous ch.mnels and displ.lys .lmplitude' and direction of blood flow. Case Report A 19-year-old man W.lS seen on August 5, rQ 80, for evaluation of p.linless oClll.tr inj('ction .md leftsided proptosis of 2 months dur.ltion. HI.' denied diplopi.l, visual loss, .md sllbjectiv(' bruit. There' was Ill~ he.ld tr.\Um.l. He h.ld .l di.\gnosis of hemophili.\ since .lge 10, but he denied episodes of spontaneous bleeding. The visual acuity W.lS 20/20 bilaterally. The episcler.ll vessels of the left eye were m.lrkedly dil.lted .lnd r.ldially arranged tow. lrds the limbus (Fig. 3). lntraocul.tr pressures were 18 mm Hg bilaterally. Hertel measurements at base 102 were right eye, 10; and left eye, 20. Ocular pulsations and orbital or cranial bruit were absent. Ophthalmoscopy was normal in both eyes. A complete blood count, erythrocyte sedimentation rate, skull x-ray, and T4 were norma\. A prothrombin time and bleeding time were norma\. An activated partial thromboplastin time was 48.4 seconds (control = 30.2 seconds), and a factor 8 assay was 5.5% (abnormal). An orbital CT scan found enlarged horizontal recti muscles and an enlarged superior ophthalmic vein on the left. Directional Doppler testing found retrograde flow in Figure 3. Ldt l'yl'. Dilall'd, tortuous <,piscil'ral v(,ssl'ls the left frontal vein (Fig. 2). Selective internal carotid angiograms found a low-flow shunt between the inferior cavernous sinus artery and the cavernous sinus on the left (Fig. 4). The patient's orbital symptoms improved shortly after he received the arteriogram, and he declined further evaluation. Discussion We have extended the use of ultrasound techniques to study the abnormal circulatory orbital dynamics in a patient with a dural carotidcavernous fistula. The normal frontal vein drains into the orbit through the superior ophthalmic vein, but, Figure 4. Selective Idt internal carotid arleriugrJm shuwin~ abnormally dilall'd inferior cavernous sinus artery (arrow). March 1982 41 Doppler SOllogr,lphy when arteriovenous fistulas involve the orbital circulation, venous blood flow becomes arterialized and exits from the orbit. Unlike the normal frontal vein, which is only weakly audible to an ultrasound receiving crystal, the frontal vein of a patient with an arteriovenous fistula generates a much higher velocity (frequency) signal, allowing the redirected blood flow to be recorded over the brow (Fig. 2). Although continuous wave, bidirectional Doppler is ideal for identifying the presence of a retrobulbar arteriovenous shunt, Doppler techniques are unable to localize the precise site of the shunt; selective carotid arteriography is necessary for further evaluating potential surgical patients. In our patient who lacked the classical features of ocular pulsations and orbital bruit, moderate epibulbar injection and left-sided proptosis were the only signs of carotidcavemous fistula. A dural shunt originating from the left inferior cavernous sinus artery was found by selective internal carotid arteriograms. Dural shunts that occur in the region of the cavernous sinus usually spring from the meningohypophyseal trunk and occur in postmenopausal women, .M who share many of the typical ophthalmic signs of the more commonly diagnosed direct carotidcavernous fistula.9. 10 Our patient was a young man not thought likely to be clinically susceptible to spontaneous dural shunt formation. However, Doppler ultrasonic testing demonstrated orbital circulation dynamics compatible with the presence of an arteriovenous fistula. Carotid arteriograms subsequently showed the intracranial dural shunt. Like other patients with these lowflow shunts whose fistulas spontaneously close' or become asymptomatic after carotid arteriograms,9 our patient required no surgical therapy. We feel that because bidirectional Doppler tests are technically easy to perform and interpret by qualified examiners, Doppler ultrasound techniques should be used in the evaluation of patients who are suspected of harboring an intracranial dural shunt. Although neuroradiologists are becoming increasingly familiar with dural shunts, the arteriographic findings are subtle, and may be overlooked." A definite arterial pulse was found in the frontal vein in our patient conclusively identifying the suspected vascular abnormality. Summary Painless left-sided ocular injection and proptosis developed in a 19-year-old man with hemophilia. Pain, ophthalmoplegia, orbital bruit, and ocular pulsations were absent. A directional Doppler evaluation found pulsatile, retrograde, arterial blood flow in the frontal vein, confirming the presence of an orbital or cranial arteriovenous fistula. Selective internal carotid angiograms demonstrated the abnormal shunt springing from the left inferior cavernous sinus artery intracranially. Shortly thereafter, the patient's symptoms spontaneously abated. Bidirectional Doppler sonography is a sensitive and useful tool in the diagnosis of dural shunts. References 1. Hyman, B.N.: Doppler sonography. A bedside noninvasive method for assessment of carotid artery disease. Am. f. Ophthalmol. 77: 227, 1974. 2. Nisbet, R.M., Barber, J.C, and Steinkuller, P.G.: Doppler ultrasonic flow detector: An adjunct in evaluation of orbital lesions. f. Pediatr. Ophthalmol. 17: 268, 1980. 3. Muller, H.R.: The diagnosis of internal carotid artery occlusion by directional Doppler sonography of the ophthalmic artery. Neurology 22: 816, 1972. 4. Brockenbrough, E.C: Screening for the prevention of stroke: Use of a Doppler flowmeter. Parks Electronics, Beaverton, Oregon, 1970. 5. Wise, G., Parker, J., and Burkholder, J.: Supraorbital Doppler studies, carotid bruits, and arteriography in unilateral ocular or cerebral ischemic disorders. Neurology 29: 34-37, 1979. 6. Katz, D.M., Smith, R.A., Otis, S.M., and Dalessio, D.J.: Doppler sonography diagnosis of cerebrovascular disease. Stroke 7: 439-444, 1976. 7. Newton, T.H., and Hoyt, W.F.: Dural arteriovenous shunts in the region of the cavernous sinus. Neuroradiology 1: 71, 1970. 8. Taniguchi, RM., Goree, J.A., and Odorn, G.t.: Spontaneous carotid-cavernous shunts presenting diagnostic problems. f. Neurosurg. 35: 384, 1971. 9. Slusher, M.M., Lennington, B.R., Weaver, R.G., and Davis, CH.: Ophthalmic findings in dural arteriovenous shunts. Ophthalmology 86: 720, 1979. 10. Biglan, A.W., Pang, D., Shuckett, E.P., and Kerber, C: External carotid-cavernous fistula in an infant. Am. f. Ophthalmol. 91: 351, 1981. 11. Costin, J.A., Weinstein, M.A., Berlin, A.J., Hardy, R.W., and Gutman, F.A.: Dural arteriovenous malformations involving the cavernous sinus: A case report. Br. f. Ophthalmol. 62: 478, 1978. Write for reprint to : James A. Rush, M.D., University of South Florida, College of Medicine, Box 21, 12901 North 30th Street, Tampa, Florida 33612. Journal of Clinical Neuro-ophthalrnology |
