You are in: eMedicine Specialties > Neurosurgery > Vascular Caroticocavernous FistulaArticle Last Updated: Dec 13, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Michael G Nosko, MD, PhD, Chief, Division of Neurosurgery, Director of Neurovascular Surgery, Medical Director of Neuroscience Unit, Associate Professor, Department of Surgery, University of Medicine and Dentistry at New Jersey Michael G Nosko is a member of the following medical societies: Academy of Medicine of New Jersey, Alpha Omega Alpha, American Association of Neurological Surgeons, American College of Surgeons, American Heart Association, American Medical Association, New York Academy of Sciences, and Society of Critical Care Medicine Editors: Duc Hoang Duong, MD, Associate Professor, Director of Neuroscience Physician Assistant Program, Departments of Neurological Surgery and Neuroscience, Epilepsy Center, Charles R Drew University; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Ryszard M Pluta, MD, PhD, Associate Professor, Neurosurgical Department Medical Research Center, Polish Academy of Sciences at Warsaw, Poland; Senior Researcher, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH; Herbert H Engelhard III, MD, PhD, Director, UIC Neuro-Oncology Program, Chief, Division of Neuro-Oncology, Associate Professor, Department of Neurosurgery, University of Illinois at Chicago; Allen R Wyler, MD, Medical Director, Northstar Neuroscience, Inc Author and Editor Disclosure Synonyms and related keywords: caroticocavernous fistula, cc fistula, dural arteriovenous fistula, arteriovenous shunting, type A caroticocavernous fistulas, type B caroticocavernous fistulas, type C caroticocavernous fistulas, type D caroticocavernous fistulas, intracavernous vessels, intracavernous arteries, intracavernous aneurysm, fibromuscular dysplasia, Ehlers-Danlos syndrome, collagen vascular diseases, atherosclerotic vascular disease, ophthalmic venous hypertension, orbital venous congestion, proptosis, chemosis, arterialization of episcleral veins, diplopia, visual loss, III cranial nerve palsy, IV cranial nerve palsy, V cranial nerve palsy, VI cranial nerve palsy, cranial nerve paralysis, central retinal vein occlusion, retinopathy, glaucoma, bruit, headache, visual loss, intracavernous internal carotid artery, cavernous sinus, dural shunt INTRODUCTIONSection 2 of 12
  The caroticocavernous fistula is a specific type of dural arteriovenous fistula characterized by abnormal arteriovenous shunting within the cavernous sinus. History of the ProcedureCase reports of dural arteriovenous fistulas were first published in the 1930s. The clinical presentation was recognized, but the pathophysiology was not well understood. During the 1970s and 1980s, the anatomy was further elucidated. Barrow and associates developed the current classification system of caroticocavernous fistulas in 1985.1 ProblemA caroticocavernous fistula (see Image 3) results in high-pressure arterial blood entering the low-pressure venous cavernous sinus. This interferes with normal venous drainage patterns and compromises blood flow within the cavernous sinus and the orbit. FrequencyCaroticocavernous fistulas represent approximately 12% of all dural arteriovenous fistulas. Type A is more common in young males. Types B, C, and D are more common in women older than 50 years, with a 7:1 female-to-male ratio. EtiologyCaroticocavernous fistulas can be caused by trauma. Blunt and penetrating head injuries can result in a caroticocavernous fistula. They also can occur spontaneously. Most caroticocavernous fistulas are of spontaneous origin and unknown etiology. PathophysiologyBlunt head injury can lead to shearing of intracavernous arteries, causing the development of a fistula. Penetrating head injury can lead to fistula formation by direct laceration of intracavernous vessels. Spontaneous fistula formation has been associated with (1) ruptured intracavernous aneurysm, (2) fibromuscular dysplasia,2 (3) Ehlers-Danlos syndrome and other collagen vascular diseases, (4) atherosclerotic vascular disease, (5) pregnancy, and (6) straining. ClinicalThe onset is usually sudden. Ocular manifestations (see Image 1) can include ophthalmic venous hypertension and orbital venous congestion, proptosis, corneal exposure, chemosis, and arterialization of episcleral veins. Other ocular manifestations may include diplopia, visual loss, cranial nerve palsy (III, IV, V, VI), central retinal vein occlusion, retinopathy, and glaucoma. Bruit and headache also may be present upon clinical presentation. INDICATIONSSection 3 of 12
A caroticocavernous fistula is not a life-threatening disease. The risk of visual loss and the severity of associated symptoms must be evaluated to determine the appropriate degree and timing of intervention. Type-A fistulas rarely resolve spontaneously. Treatment is recommended for intolerable bruit, progressive visual loss, and the cosmetic effects of proptosis. Types B, C, and D fistulas have a higher incidence of spontaneous resolution. RELEVANT ANATOMYSection 4 of 12
The cavernous sinus is a network of venous channels traversed by the intracranial portion of the internal carotid artery. The internal carotid artery gives rise to several intracavernous branches. These are the meningohypophyseal and inferolateral trunks. These vessels branch to provide arterial blood to the nerves and dura of the cavernous sinus and the pituitary gland. The external carotid artery provides several branches to the dura of the cavernous sinus and forms anastomoses with the branches of the internal carotid artery. Type A fistulas consist of a direct connection between the intracavernous internal carotid artery and the cavernous sinus. They usually are high-flow and high-pressure fistulas. Type B fistulas consist of a dural shunt between intracavernous branches of the internal carotid artery and the cavernous sinus. Type C fistulas consist of a dural shunt between meningeal branches of the external carotid artery and the cavernous sinus. Type D fistulas are a combination of types B and C, with dural shunts between internal and external carotid artery branches and the cavernous sinus. Types B, C, and D tend to be lower-flow and lower-pressure fistulas with a slower progression of signs and symptoms. CONTRAINDICATIONSSection 5 of 12
No a priori contraindications exist for the management of these lesions. Each patient must be evaluated individually. Generally, the lesions should be managed as aggressively as required to abort the signs and symptoms. Management techniques may be contraindicated if the patient cannot tolerate the possible complications of the treatment. WORKUPSection 6 of 12
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TREATMENTSection 7 of 12
Medical therapyIn the acute setting of vision loss and/or paralysis of cranial nerves, glucocorticosteroids (eg, dexamethasone) may be used while waiting for definitive diagnostic studies and treatments. Surgical therapyThe definitive management of a caroticocavernous fistula is obliteration of the fistulous connection with restoration of normal arterial and venous flow. This is achieved most often through an endovascular approach. After complete delineation of the fistulous tract, an approach can be planned to close the fistula. Type-A fistulas usually are approached through the internal carotid artery. A detachable balloon then can be positioned to occlude the fistula while maintaining patency of the internal carotid artery. Venous approaches through the internal jugular vein and the petrosal sinus may allow access to the fistula from the venous side. Guglielmi detachable coils also may be used and are becoming increasingly popular. Type B, C, and D fistulas have smaller fistulous connections and usually are not amenable to the aforementioned treatment approaches. Carotid self-compression for 20-30 seconds 4 times per hour may lead to thrombosis of the fistula. Patients are instructed to compress the carotid artery on the side of the lesion using their contralateral hand. Should the patient develop cerebral ischemia during the compression, the contralateral hand likely will be affected, releasing the compression. If compression is not effective or if a more rapid intervention is indicated, selective endovascular embolization of the fistula through the external carotid artery usually is effective. Several choices of embolic material are available, although polyvinyl alcohol usually is preferred. Occasionally a fistula may require an endovascular approach through the superior ophthalmic vein. This requires surgical exposure of the vein to allow placement of the catheter. Direct surgical exposure and obliteration of the fistula has been described. This rarely is indicated because endovascular approaches have been developed. Severely refractory fistulas can be treated by surgical or endovascular sacrifice of the internal carotid artery. This too, rarely is indicated. Follow-upPatients usually require a follow-up angiogram to ensure that the fistula has not recurred or that alternate fistulous pathways have not developed. COMPLICATIONSSection 8 of 12
Complications in untreated lesions usually are limited to visual loss, cranial nerves paralysis, and the cosmetic concerns of proptosis. Complications of treatment include the standard complications of cerebral angiography. Arterial and venous compromise also may occur, yielding cerebral or retinal ischemia and resultant infarction. OUTCOME AND PROGNOSISSection 9 of 12
Patients with caroticocavernous fistulas generally have a good prognosis. These fistulas are associated with a high incidence of spontaneous resolution. Persistent lesions respond well to intervention. The risk of nonophthalmologic neurological complications is not significant; however, persistent untreated lesions may cause significant visual complications. FUTURE AND CONTROVERSIESSection 10 of 12
As techniques for endovascular stenting are developed further, internal carotid artery stenting across the fistula may have a role. This may provide a safer treatment option with respect to maintaining patency of the internal carotid artery while obliterating the fistula. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Caroticocavernous Fistula excerpt Article Last Updated: Dec 13, 2007 | ||||||||||||||||||||||||||
