【摘要】目的：报告外伤后颈动脉海绵窦瘘患者应用螺圈栓塞的成功经验。
方法：连续病例。
结果：两名颈动脉海绵窦瘘（CCF）患者成功接受了螺圈栓塞治疗。他们分别在机动车事故后2wk和4mo出现CCF的临床症状。一名患者视力良好但眼内压（IOP）升高，另一名则视力低下伴有临界眼内压。CCF的诊断均得到脑血管造影证实，采用螺圈栓塞治疗后两名患者视力恢复正常，在未用任何抗青光眼药物前提下眼压降至正常范围。CCF的症状诸如眼球突出，眼肌麻痹，结膜充血水肿，眼眶杂音及眼底改变也随之消失。
结论：颈动脉海绵窦瘘宜早诊断和治疗以避免发生视力丧失严重并发症的发生，血管内栓塞是当代治疗选择。
【关键词】 颈动脉海绵窦瘘；视力丧失；栓塞
AbstractAIM: To report cases of carotid cavernous fistula in post traumatic patients successfully treated with coil embolization.METHODS: Two cases of direct carotid cavernous fistula (CCF) underwent successful coil embolization. Both patients presented with clinical features of CCF following motor vehicle accident at two weeks and four months. One patient had good visual acuity with raised intraocular pressure (IOP) and the other had poor vision with borderline IOP. The diagnosis was confirmed with cerebral angiography. Coil embolization were performed in both cases.RESULTS: After the procedure the vision was back to normal and IOP came down to normal range without antiglaucoma. The features of CCF were also resolved, which included proptosis, ophthalmoplegia, chemotic conjunctiva, orbital bruit and fundus changes.CONCLUSION: Carotid cavernous fistula should be diagnosed and treated early to prevent serious ocular complication of vision loss. Endovascular embolization is the current treatment of choice.
KEYWORDS: carotid cavernous fistula; visual loss; embolization
INTRODUCTION
Carotid cavernous fistulas (CCF) are abnormal communications between the carotid artery and the cavernous sinus. The direct type, also known as type A, represents 7090% of all carotid cavernous fistula cases. Type A fistulas consist of a direct connection between the intracavernous internal carotid artery and the cavernous sinus[1]. They are usually highflow and highpressure fistulas. About 76% of carotid cavernous fistula cases are due to trauma[2]. Known ocular complications of CCF include visual loss due to multiple insults to the visual system, cranial nerves paralysis and cosmetic concerns of proptosis. Late and untreated CCF may lead to irreversible blindness in which 89% of patients eventually experienced loss of vision. Early and prompt treatment had preserved vision in 94% of cases[2]. We would like to report two patients who experienced recovery of vision and normalized intraocular pressure (IOP) after successful occlusion of the fistula.
CASE SERIES
Case One A 25yearold army man presented with painless protrusion of left eye for four months duration associated with redness, blurred vision, diplopia and left sided tinnitus. It progressively worsened for one month prior to presentation. Patient had history of motor vehicle accident with left sided head injury four months prior to the onset of the symptoms.
On examination, vision was 6/6 in the right eye and 6/60 in the left eye. There was ptosis of the left eye with pulsatile axial proptosis. Hertel exophthalmometer measured 5mm. The conjunctiva was congested and prolapsed inferiorly with dilated episcleral vessels of corkscrew appearance (Figure 1). The extraocular muscles movements of the left eye were limited in all directions. There was no relative afferent pupillary defect. Cornea reflex of the left eye was impaired with reduced sensation over ophthalmic division of the 5th cranial nerve. There was presence of orbital bruit over the left eye. The left intraocular pressure (IOP) was 22mmHg and it was 16mmHg in the right eye. Anterior segment was normal for both eyes. The left fundus showed hyperemic disc, generalized dot blot hemorrhages with dilated and tortuous retinal vessels. The right fundus was normal. Ear, nose and throat examination revealed no abnormality.
A diagnosis of left carotid cavernous fistula was made and it was confirmed by angiogram. Cerebral angiography showed opacification of the carvernous sinus, superior and inferior petrosal sinus, transverse sinus and superior ophthalmic vein on the left internal carotid artery run. His CT scan of brain showed loss of concavity of left cavernous sinus and dilated superior ophthalmic vein (Figure 2).
Patient underwent embolization initially by detachable balloon. However, due to large fistula, the balloon was changed to detachable coil, total of 25 coils were used. Post embolization, left distal carotid artery was completely occluded. His borderline IOP was monitored closely and no treatment started.
On followup at one month after the procedure, his vision was back to 6/6. There was no more proptosis. Hertel measurement was same for both eyes. The conjunctiva was white and no bruit was heard. Extraocular movement also recovered to normal. His left fundus showed slightly dilated but not tortuous vessels. The retinal arteries looked normal. There were no more retinal hemorrhages. He had no more tinnitusCase Two A 14yearold Malay boy with polytrauma presented with right eye proptosis at two weeks after the trauma. It was progressive in nature and painful. There was no blurring of vision. On examination, vision was 6/6 in both eyes. Hertel exophthalmometer measured 7mm. There were axial proptosis, non pulsatile, chemotic conjunctiva, corkscrew episcleral vessels, total ophthalmoplegia and orbital bruit in the right eye. Fundus was normal. He had raised IOP (25mmHg 48mmHg) and was treated with antiglaucoma medicine. The left eye was normal.
Cerebral angiography showed features of right carotid cavernous fistula evidenced by direct communication between the cavernous part of right internal carotid artery and right cavernous sinus. The superior ophthalmic vein and inferior petrosal sinus were dilated. His CT scan of brain showed dilated and tortuous right superior ophthalmic vein with loss of concavity of right cavernous sinus.
Patient underwent coil embolization (5 coils of different sizes were used) about three weeks after diagnostic imaging as he was not stable. The procedure was uneventful and after the embolization the right internal carotid artery was successfully occluded.
On followup, his IOP came down and his antiglaucoma eyedrops was tapered down. Currently he is not on any antiglaucoma eyedrops. His proptosis resolved within two weeks post embolization so did other ocular features of CCF that he had. Unfortunately his right abducent nerve remained affected and he had diplopia on right gaze.
DISCUSSION
Carotid cavernous fistulas (CCF) of traumatic origin are more common in males with ratio of 2∶1. It can occur due to penetrating injury to the internal carotid artery or due to laceration from a bone spicule or from a basal skull fracture involving floor of middle cranial fossa[3]. Other causes of CCF are surgical damage, rupture of an intracavernous aneurysm, connective tissue disorder, vascular disease and dural fistula[4]. Direct communication between the high pressure lumen of the artery and low pressure of the cavernous sinus causes a rise in the mean pressure within the venous channel. The orbital veins which communicate with the cavernous sinus develop high pressure in the vessels and produced signs and symptoms of venous congestion. These include proptosis, chemosis, corkscrew appearance of vessels, bruit, raised intraocular pressure and ophthalmoplegia[5,6]. Our patient presented with all the signs mentioned. Proptosis was present in 94% of cases, followed by bruit(75%), chemosis(71%), ophthalmoplegia and diplopia(60%) and loss of vision(46%)[3]. Symptoms were usually abrupt in onset and rapidly progressive.
Diplopia and ophthalmoplegia occur due to mechanical compression of the cranial nerves and congestion of eye muscles as a result of decreased arterial flow to the cranial nerves[7]. Among the cranial nerves, abducens nerve is the commonly affected due to its location floating freely within the cavernous sinus. Abducens palsy occurs in 49%85% of CCF patients[8,9]. One of our patients had residual abducent palsy of the right eye. Raised intraocular pressure occurs due to raised pressure in episcleral veins and presents in 30%50% of cases. It is also due to the proptosis itself[7]. Palestine et al [10]in 1981 found out elevated intraocular pressure did not seem to be a major cause of visual loss. Ophthalmoscopic finding in CCF varied in severity from normal to as severe as choroidal and exudative retinal detachment. Dilated retinal veins, ipsilateral optic disc swelling, intraretinal hemorrhages and vitreous hemorrhages are associated with CCF[2]. Disc edema and venous stasis are common and may be complicated by retinal vein occlusions[11]. Jorgensen JS and Guthoff R[12] in 1987 analyzed the fundus changes of 20 patients with CCF and found out that 4 patients had choroidal detachment, 2 had exudative retinal detachment, 3 had central venous thrombosis and 1 had papilledema. In our patients, the retinal hemorrhages disappeared after the offending fistula was obliterated. However, the hyperemic disc could be an early disc swelling change. It was also reported that CCF increased the risk of central retinal artery occlusion because of the high intraocular pressure[2,8,13]. Our patient was lucky for not having any vessels occlusion despite the raised IOP that have to be controlled with antiglaucoma medicine.
Visual impairment affects 60%90% of patients and may become progressive if not treated[2]. Naesens et al[2] reported total visual loss that happened in as many as 25% of the cases but maybe reversible. Retinal dysfunction due to ischemia produced by stagnant flow anoxia, mechanical axonal conduction block as a result of high intraocular pressure due to secondary glaucoma, optic nerve compression by distended cavernous sinus, vitreous hemorrhages, uveal effusion and retinal detachment are the insults that can result in reversible visual loss. Irreversible blindness is due to optic neuropathy either from trauma to the nerve or infarction during the original injury.
The definitive diagnostic test for CCF is cerebral angiography. All the arteries which contribute to the formation of the fistula can be visualized during the procedure. Other imaging modalities like contrast enhanced CT and magnetic resonance angiography may show enlarged tortuous superior ophthalmic veins ( the ‘hockey stick sign’) in CCF patients. Radiographic findings that point to CCF as a diagnosis are lateral bulging of the cavernous sinus wall, edematous fat in the orbit and enlargement of the extraocular muscles[2,1416].
The goal of treatment in CCF is occlusion of the fistula. In direct CCF, treatment aims to relieve orbital symptoms and prevent the development of intracranial venous hypertension[16]. Indications for urgent treatment include severe proptosis with pain and high intraocular pressure, diminished visual acuity, corneal exposure, epistaxis and sphenoid sinus aneurysm[16,17]. The treatment of choice for direct CCF is transarterial embolization with detachable balloons[18]. The procedure is performed under general anesthesia. A latex or silicone balloon mounted on a microcatheter is introduced in the cavernous carotid artery via percutaneous approach of the femoral artery. The device is carried to the venous site of fistula with the help of high flow shunt and then gets inflated and detached in situ. However, this procedure is unsuccessful in 5%10% of cases[19]. Failure occurs due to intimal flaps or the fistula orifice is too small or too big. In our case, the balloon failed to detach as the communication was quite large. Platinum coils, an alternative for balloon embolization, are used in cases of failed balloon like in our case. The advantages of the coils are that it is easy to control their placement whether to retrieve, reposition or exchange if necessary. A major disadvantage of coiling is its high cost[2,13]. When transarterial approach is not possible, transvenous access is another treatment option. The cavernous sinus may be reached via the valveless inferior petrosal sinus from the jugular vein[13].
Other treatment options include liquid embolizing agents such as Nbutyl2cyanoacrylate and ethyl vinyl alcohol copolymers, but they cannot be used in high flow CCF due to their potential risks for cerebral infarction by the uncontrolled escape of the polymers during injection and deposition. Manual compression where patient compresses the carotid artery six times a day, each time for 1030 seconds works in low flow fistulas with less aggressive symptoms. However, it takes about three and a half years to cure the fistulas[20]. The last option for closing a fistula is surgery. Direct surgical approach is extremely invasive and is not preferred.
In conclusion, results are excellent in the treatment of CCF when the diagnosis is made at early stage. A diagnosis of CCF should not be missed especially in traumatic patient as they usually present with high flow fistula. A high flow fistula will present with a rapid and progressive history of orbital symptoms. Vision remains the important and urgent indicationfor intervention in CCF patient. Endovascular embolization technique is proven to be the best method for the treatment of CCF.
Acknowledgments:Department of Radiology, Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
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