A woman in her early 50’s presents with double vision and occasional tinnitus. On detailed neurologic exam, a right VI th nerve palsy was observed. Otherwise, she was neurologically asymptomatic. CT Angiography and Venography suggest complete occlusion of the right transverse, sigmoid, and jugular sinuses. We performed a Cerebral Angiogram which confirmed the diagnosis of complete right transverse thru jugular venous occlusion, with venous hypertension and anterior collateral drainage into the pre-mesencephalic system (Figure 1. A and B). In addition, a dural arterial-venous fistula (DAVF) of the right cavernous sinus (contributing to her cranial neuropathy) was observed (Figure 2. A). |
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Figure 1. A) AP Right Internal Carotid Artery Injection, Venous Phase showing poor filling of the Right Transverse sinus (yellow), and abnormal filling of cortical veins (red). |
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Figure 1. B) Lat View, Venous Phase, right vertebral injection, showing profound cortical venous hypertension of the posterior fossa, right transverse sinus occlusion (dotted circle). The retrograde filling of the veins of the posterior fossa are seen outlining the cerebellum and filling the pre-mesencephailc veins (red arrow). |
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Figure 2. Lat Right Internal Carotid injection, mid arterial phase. The venous structures around the Petrous portion of the internal carotid are robustly filled, by the dialated dural arterial supply from the internal carotid artery (red arrows). The abnormal drainage is posterior into the sinuses of the posterior fossa, as well into the pharyngeal veins (dashed blue arrows). |
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Fortunately, no high-risk features of cortical venous reflux and advanced grade hemorrhagic risk were observed. She underwent extensive evaluation for hypercoagulation syndromes and was continued on medical therapy of Coumadin anticoagulation (also prescribed for his atrial fibrillation). On 6m, 1, and 2 year monitoring, her clinical and imaging findings continue to remain stable with absence of progression or new symptoms, with mild venous hypertension being collateralized well within deep venous systems.
Dural AVFs of the Cavernous Sinus can occur because of traumatic or spontaneous communication in the walls of the intra-cavernous internal carotid artery or its branches directly to the cavernous sinus resulting in short-circuiting or shunting of high pressure arterial blood into the venous system of the cavernous sinuses. Dural sinus stenosis and occlusion as well as hypercoagulable states are often associated. Indirect or Dural carotid-cavernous sinus fistulae are characterized by a communication between one or more meningeal branches of the internal carotid artery and/or the external carotid artery with the cavernous sinus. These fistulae usually have lower rates of arterial blood flow initially but may progress to develop higher pressure and cortical venous reflux and associated risks of visual deficits and hemorrhagic strokes. These lesions may represent congenital or acquired arteriovenous malformations, which develop spontaneously or in association with atherosclerosis, hypercoagulation states, trauma, iatrogenesis, infection, systemic hypertension, collagen vascular disease, and peri-partum situations in women. Early evaluation by a neurovascular specialist is recommended for patients presenting with new onset or progressive pulsatile tinnitus, especially in patients with associated visual symptoms (chemosis, proptosis, diplopia) and can often lead to successful treatment and prevention of serious life-threatening complications of the disease when necessary. (Reference 1)
For this woman, Gama Knife Radio Surgery (GKRS) could be considered. The mildness of her syndrome without serious bleeding risk did not, in our judgement, justify the risk. Although the cranial nerves are less radio-sensitive than other structures, and the amount of radiation required for Dural AVMs is often less than Pial Brain AVMs, it is not without risk of permanent damage, Cavernous DAVF often resolve spontaneously, though in this patient, on anticoagulation it may be less likely. In DAVFs, GKRS achieves 41-90% obliteration rates at the second post-GKRS year with a hemorrhage rate below 5%. Debate continues as to whether GKRS might serve as a first-line solo therapeutic modality given its latency period. Although the post-GKRS outcomes are thought to differ among lesion locations, further outcome analyses regarding DAVF locations are required. (Reference 2 and 3)
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KEY LEARNING POINTS:
- Cavernous dural AVF’s often present as a sixth cranial nerve deficit. The location of the drainage determines symptoms – i.e. Out the eye > proptosis and chemosis, Out the petrosal sinuses > tinnitus/bruit, into the cortical veins > bleeds and strokes
- Not all DAVF’s need to be treated and a personalized assessment of each patient’s pathology, presentation, symptoms, and risks need to be assessed and managed. All DAVMs that need to be treated can be, with a variety of strategies including endovascular, radiosurgery, microsurgery, or medical regimens tailored to the disease.
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REFERENCES:
- Cognard, C., Gobin, Y. P., Pierot, L., Bailly, A. L., Houdart, E., Casasco, A., Chiras, J., & Merland, J. J. (1995). Cerebral dural arteriovenous fistulas: clinical and angiographic correlation with a revised classification of venous drainage. Radiology, 194(3), 671–680.
- Wu, H. M., Pan, D. H., Chung, W. Y., Guo, W. Y., Liu, K. D., Shiau, C. Y., Wang, L. W., & Chen, S. J. (2006). Gamma Knife surgery for the management of intracranial dural arteriovenous fistulas. Journal of neurosurgery, 105 Suppl, 43–51.
- Söderman, M., Edner, G., Ericson, K., Karlsson, B., Rähn, T., Ulfarsson, E., & Andersson, T. (2006). Gamma knife surgery for dural arteriovenous shunts: 25 years of experience. Journal of neurosurgery, 104(6), 867–875.
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