DEPARTMENT OF OPHTHALMOLOGY
FACULTY OF MEDICINE PADJADJARAN UNIVERSITY NATIONAL EYE CENTER CICENDO EYE HOSPITAL BANDUNG
Case Report : Indirect Low Flow Carotid Cavernous Fistula Presenter : Yasir Hady
Supervisor : Rusti Hanindya Sari, dr., SpM(K)
Has been reviewed and approved by Supervisor of Neuro-Ophthalmology Unit
Rusti Hanindya Sari, dr., SpM(K)
Tuesday, 18th July 2023
Indirect Low Flow Carotid Cavernous Fistula: A Case Report
Abstract
Introduction: Carotid Cavernous Fistula (CCF) is a rare clinical presentation. It is result of abnormal connection between carotid arterial system and venous vessel of cavernous sinus. Indirect CCF commonly occur in older female patients and may resolve spontaneously without surgical intervention. External manual carotid compression is one of treatment of choice in indirect low flow CCF.
Purpose: To report a case of low flow carotid cavernous fistula that treated with external manual carotid compression.
Case report: A 55 year-old female came with chief complaint of blurred of vision on left eye (LE) since 6 months ago. Complaint accompanied by redness and tearing on the left eye, with tinnitus that occasionally happened. She had history of hypertension. She denied any history of trauma. CT scan revealed dilated superior ophthalmic vein on the left eye and suggested to do Digital Substraction Angiography (DSA). She was instructed to do external manual carotid compression (EMCC) daily while waiting to go to Neuro-surgery Department. After two weeks the symptom were improved.
Conclusion: Indirect CCF may occur spontaneously especially in older female patients.
Early diagnosis and appropriate treatment is essential to avoid vision and life-threatening complication. EMCC remains an established treatment for indirect low flow CCF.
Keyword: Carotid cavernous fistula, indirect, low flow, external manual carotid compression.
I. Introduction
Carotid Cavernous Fistula (CCF) is the result of abnormal connection between carotid arterial system and venous vessel of cavernous sinus. CCF can be classified based on etiology (traumatic or spontaneous), hemodynamic feature (high or low flow), and anatomy involved (direct or indirect/dural). Patients with CCF commonly present with ophthalmic manifestations due to venous congestion of orbit from cavernous sinus.1–3
Another classification of CCF according to Barrow classification can be divided into four types from type A, B, C, and D. Type A CCF can also be classified as direct, while type B, C, and D can be classified as indirect CCF. The incidence of traumatic CCF is more than 70% and usually occurred in young male patients following closed head injury. Spontaneous CCF was reported for the remaining 30%, usually occurred in postmenopausal patients.1,4,5
The management of CCF depends on etiology, clinical manifestation, radiographic findings, and risk for ophthalmic or neurologic complications. Direct CCF commonly symptomatic and treated urgently such as endovascular
embolization with coiling or liquid agents. Patients with asymptomatic indirect CCF can be safely observed and may resolve spontaneously. Treatment modality including external manual carotid compression is a useful technique for indirect low flow fistulas. Early diagnosis and appropriate treatment is essential to avoid vision and life-threatening complication.1–3 The purpose of this study is to report a case of indirect low flow carotid cavernous fistula treated with external manual carotid compression.
II. Case Report
A 55 year-old female came to Neuro-Ophthalmology outpatient clinic Cicendo Eye Hospital on May 4th 2023 with chief complaint of blurred of vision on left eye (LE) since 6 months ago. She also complaint redness and tearing on the left eye, and tinnitus that occasionally happened. Patient had prior history hypertension since 6 months ago without antihypertensive medication. She denied any headache, eye pain, double vision, nor eye protrusion. There were no history of trauma or previous eye surgery. Patient had no prior history of diabetes, dyslipidemia, or other systemic diseases.
Figure 1. Ocular motility on both eye
Physical examination revealed consciousness was fully alert with blood pressure 172/97 mmHg and other vital signs within normal limit. General examination within normal limit. Other neurological examination was within normal limit.
Ophthalmology examination revealed uncorrected visual acuity (UCVA) was 0.63
with pinhole 1.0 on right eye (RE) and 0.4 with pinhole 0.63 on left eye (LE).
Refractometry revealed S+1.50 C-0.50 x85 on RE and S+2.00 C-0.75 x5 on LE.
Patient’s Best Corrected Visual Acuity (BCVA) on RE using S+0.75 was 1.0 and BCVA on LE using S+1.00 was 0.63.
Ocular position were orthotropia, ocular motility were full to all directions, intraocular pressure using non-contact tonometry was 12 mmHg on RE and 30 mmHg on LE. Anterior segment examination was within normal limit on the right eye. Anterior segment examination on the left eye found episcleral injection with corkscrew appearance on conjunctiva, minimal edema on cornea, anterior chamber with Van Herrick (VH) grade III with no flare and cells, light reflex examination revealed grade II Relative Afferent Pupillary Defect (RAPD) on the left eye, and lens relatively clear. No ocular bruit was heard during auscultation on both eye.
Figure 2. anterior segment left eye, revealing corkscrew appearance.
Funduscopy examination on the right eye showed round papil with firm border, flat retina, and good foveal reflex. Funduscopy on the left eye showed round papil with firm border, with mild retinal vascular tortuosity, flat retina, and diminished foveal reflex. Ishihara color plate, amsler grid, and contrast sensitivity was within normal limit on both eye. Other neurological examination was within normal limit.
Figure 3. Fundus photography and Ocular Computed Tomogrphy (OCT) of optic disc
Ocular Computed Tomography (OCT) of optic disc showed normal Retinal Nerve Fiber Layer (RNFL) thickness and normal average cup to disc ratio on both eyes. Contrast enhanced Computed Tomography (CT) scan of head orbita revealed dilated diameter of left superior ophthalmic vein ±3.20 mm, compared with diameter of right superior ophthalmic vein ±1.90 mm (normal diameter 1.0 – 2.9 mm), suggested left carotid cavernous fistula or cavernous hemangioma. Suggested to do Digital Substraction Angiography (DSA). It was found bilateral maxillary sinusitis. There were no other abnormality found in right retrobulbar, optic nerve, and bilateral ocular bulbi.
Figure 4. Contrast Enhanced Computed Tomography Scan of head orbita.
Patient was diagnosed with suspected indirect carotid cavernous fistula (low flow) LE with secondary glaucoma LE and hypertension. Patient was consulted to Glaucoma unit and Neuro-surgery Department for further evaluation. Patient was given citicholine tablet 1x1000mg, timolol maleate 0.5% 2x drop LE, acetazolamide tablet 3x250mg daily, kalium chloride tablet 1x300mg daily, and instructed to do external manual carotid compression daily. Patient has not visited the Neuro-surgery Department until now, she confess that she was afraid.
Patient came to control 2 weeks later with slight improvement on her complaint.
Blurry vision on LE started to diminished with BCVA on both eyes was 1.0, eye redness seems decreased, and no tinnitus were felt. Intraocular pressure (IOP) on
LE was 22 mmHg on antiglaucoma medication. Anterior segment on the LE revealed corkscrew appearance on conjunctiva, decreased episcleral injection, clear cornea, anterior chamber with VH grade III with no flare and cells, light reflex examination revealed grade II Relative Afferent Pupillary Defect (RAPD) on the left eye, and lens relatively clear.
Figure 5. Illustration of External Manual Carotid Compression
Funduscopy examination on the left eye showed round papil with firm border, with mild retinal vascular tortuosity, flat retina, and diminished foveal reflex.
Ishihara color plate, amsler grid, and contrast sensitivity was within normal limit on both eye. No bruit was heard during auscultation on both eye. Patient still instructed to do the external manual carotid compression until DSA procedure is done.
Figure 6. Anterior segment of the left eye on 2 weeks follow up
III. Discussion
Carotid cavernous fistula (CCF) is a rare clinical presentation, caused by abnormal connections between cavernous sinus and carotid artery or its branches.
This cause high arterial pressure into normally low-pressure venous circulation of cavernous sinus. This high-pressure connection may reverse blood flow within superior ophthalmic vein and produce venous congestion within orbit. The classic sign of CCF is arterialization of conjunctival vessels.1,3,6 This patient had clinical feature as marked conjunctival injection which correspond with the classic sign of CCF.
Carotid cavernous fistula can be classified by etiology into traumatic or sponatenous, by its haemodynamic behavior into low or high flow, and by its structure into direct or indirect. Direct CCF is high-flow connection between internal carotid artery and cavernous sinus. Direct CCF most commonly occur after severe head trauma and produce a cranial bruit. Indirect (dural) CCF is low-flow connections mediated by small arterial feeders of the internal or external carotids.
Indirect CCF often occur spontaneously, especially in older women. The sequence of events leading to indirect fistula formation is not known. Another classification by Barrow et al. was based on the vascular systems involved. Type A or direct CCF involves direct connection between internal carotid artery and cavernous sinus. This type usually results from trauma, aneurysm of internal carotid artery, and iatrogenic. Type B, Type C, and Type D were classified as indirect CCF and usually results from hypertension, fibromuscular dysplasia, and Ehler Danlos Type IV.
Type B involves meningeal branch of Internal Carotid Artery and Cavernous Sinus.
Type C involves meningeal branch of External Carotid Artery and Cavernous Sinus. Type D involves meningeal branch of Internal Carotid Artery, External Carotid Artery and Cavernous Sinus.1,4,5,7 This patient is a female 55 years old, had no previous history of trauma, therefore it is spontaneous and classified into indirect CCF.
Clinical manifestation of CCF were described as triad of pulsatile exophthalmos, orbital bruit, and chemosis. Other symptoms include proptosis, elevated intraocular pressure, diplopia, ocular pain, ischemic optic neuropathy, choroidal effusions,
cerebral venous infarction resulting from venous hypertension, and cranial nerve palsy. It was correlated with the proximity to internal carotid artery in cavernous sinus. Diplopia occur from congestion of extraocular muscle or involvement of any CN in cavernous sinus. The most common cranial nerve palsy involved were the abducent nerve palsy. Pulsatile tinnitus may present.3,6,8,9 This patient had symptom such as elevated intraocular pressure and pulsatile tinnitus.
Figure 8. Barrow classification of CCF.
Source: Ramadhoni et al4
Diagnostic workup includes several imaging modalities. Imaging may show an enlargement of superior ophthalmic vein. Magnetic Resonance Angiography (MRA), Computed Tomography Angiography (CTA), or cerebral angiography is often necessary to determine location and configuration of fistula. CT Scan and MRI can show orbital edema, detect skull base fracture, and engorgement of superior orbital vein. MRA and CTA usually shows internal carotid artery aneurysm and enlargement of cavernous sinus. Digital Substraction Angiography remains the gold standard in CCF diagnostic. It can detect the filling of cavernous sinus and determined the haemodynamic behaviour.3,4,6,8,10 This patient had done CT scan which revealed dilated superior ophthalmic vein in the left eye, further confirmation with MRA / CTA and DSA should be done to determine the fistula.
Management of CCF was classified based on its etiology. Both types of fistulas may be successfully treated with interventional radiologic techniques or radiosurgery. Thrombogenic materials such as coils, beads, or balloons may be used to eliminate the abnormal vascular flow. Direct CCF usually can’t close
spontaneously thus needed an endovascular intervention. The goal of the treatment is to cease blood flow into cavernous sinus and reconstruct internal carotid artery.
Coil Embolization and stents usually used whether via transvenous approach of superior/inferior orbital vein or via transarterial approach of internal carotid artery.
Indirect CCF usually can close spontaneously in 60% of patients due to local thrombosis of superior orbital vein. External manual carotid compression can occlude the anastomosis in 30% of patients. Endovascular intervention can be considered in uncontrollable IOP, diplopia, proptosis with corneal exposure, optic neuropathy, retinal ischemia, and severe bruit.3,4,6,9,10 This patient had not been treated with any interventional approach.
External manual carotid compression (EMCC) is a recognized treatment for low- flow indirect CCF. A case series by Kalsi et al. showed that patients who had low flow fistulas and high intraocular pressure could successfully be treated with EMCC. EMCC is thought to produce thrombus in the cavernous sinus.
Compression of the carotid is thought to reduce blood flow through the fistula and alter flow dynamics. Compression of jugular vein also reduce venous outflow and increase pressure within cavernous sinus. This combination reduced flow and stasis to produce thrombosis within cavernous sinus and its branches, causing resolution of the fistula.2,5,7
EMCC is not free of risks. Patients with atherosclerotic disease and are at significant risk of stroke from embolic disease and vasovagal episodes, stimulation of carotid may lead to arrhythmia, heart block, and syncope. There is theoretical risk of dislodging emboli from a ruptured plaque which may lead to stroke. Other potential complication include central retina vein hemorrhage and transient monocular blindness. It is advised to use the contralateral hand to the side that needed compression, as if the patients were to lose consciousness, the hand would fall away and stop compressing the carotid. EMCC remains an established treatment for indirect low flow CCF, and should be considered as a first-line treatment, especially where endovascular services are not available.2,5,7 This patient had been instructed to do EMCC as described, with improvement of her symptoms after doing EMCC daily.
IV. Conclusion
Indirect CCF may occur spontaneously especially in older female patients. Early diagnosis and appropriate treatment is essential to avoid vision and life-threatening complication. Various treatment had been available, with the simplest procedure is EMCC that remains an established treatment for indirect low flow CCF.
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