Transverse–Sigmoid Sinus Dural Arteriovenous Fistula Concurrent With Bilateral Venous Sinus Occlusion

Abstract

Background and significance:

Dural arteriovenous fistula (DAVF) is a relatively rare type of cerebrovascular malformation with unknown pathogenesis. Here, the authors report a patient with DAVF in the left transverse–sigmoid sinus (Cognard type III) combined with occlusions of the left sigmoid sinus and right transverse sinus. The authors describe and discuss their successful treatment approach, with the aim to improve the management of this rare disorder.

Case presentation:

A 59-year-old man presented with dizziness, headache, vomiting, and unsteady gait. His digital subtraction angiography evaluation indicated DAVF in the left transverse–sigmoid sinus (Cognard type III) combined with occlusions of the distal 1/3 of the left sigmoid sinus and the proximal one-third of the right transverse sinus. After balloon angioplasty and stenting, blood flow was restored in the occluded sinuses. The DAVF was treated by embolization. The patient had a satisfactory recovery with significantly improved clinical symptoms.

Conclusion:

In patients with transverse–sigmoid sinus DAVF, satisfactory venous reflux should be ensured. In patients with concurrent DAVF and sinus stenosis or occlusion, it is important to reestablish antegrade venous blood flow first. It is feasible and safe to simultaneously embolize DAVF after the venous reflux can be reestablished.

CASE PRESENTATION

A 59-year-old man was admitted to our hospital because of a sudden onset of dizziness for 1 week with an unsteady gait for 3 days. After admission, he had progressively worsened altered mental status, headache, nausea, vomiting, and further deterioration of unsteady gait that required assistance to stand up. A lumbar puncture revealed an intracranial pressure of 280 mm H₂O. The digital subtraction angiography evaluation indicated a dural arteriovenous fistula (DAVF; Cognard type III) in the left transverse–sigmoid sinus with occlusions of the distal, one-third of the left sigmoid sinus, and the proximal, one-third of the right transverse sinus (Fig. 1 A–D). During the early arterial phase, retrograde blood flow in the tortuous veins was observed in the entire bilateral cerebral hemisphere cortex. A proportion of this blood was drained into the ipsilateral internal jugular vein through the venous anastomosis to the two-thirds of normal blood vessels distal to the occluded sinus. Another proportion of blood refluxed through the straight sinus, superior sagittal sinus, and cortical venous anastomosis to reach the cavernous sinus and Sylvian vein, and then returned to the bilateral internal and external jugular veins. We made the diagnosis of DAVF (Cognard type III) in the left transverse–sigmoid sinus with occlusions of the distal, one-third of the left sigmoid sinus, and the proximal, one-third of the right transverse sinus.

FIGURE 1.

Green arrows depict the direction of blood flow. (A) The ascending pharyngeal artery, occipital artery, middle meningeal artery, and superficial temporal artery supplied the blood to the arteriovenous fistula. (B) The blood refluxed from the proximal, one-third of the left sigmoid sinus, through the ipsilateral transverse sinus to the straight sinus and superior sagittal sinus. Retrograde blood flow was observed throughout the bilateral cortical veins of the cerebral hemispheres in the early arterial phase. The proximal, one-third of the right transverse sinus, was occluded. The distal, one-third of the left sigmoid sinus, was occluded. (C and D) A proportion of the retrograde blood flow returned to the ipsilateral internal jugular vein through a venous anastomosis drained to two-thirds of the normal vessels distal to the occluded right transverse sinus. Another proportion of blood refluxed through the straight sinus, superior sagittal sinus, and cortical venous anastomosis to reach the cavernous sinus and Sylvian vein, and then returned to the bilateral internal and external jugular veins. (E) The aberrant vessels were seen to be, basically, disappeared. (F) The normal downward blood flow was, basically, restored, with blood returning to the sinus sink through the superior sagittal sinus, the straight sinus, and the left transverse sinus, and then to the jugular venous system through the right transverse sinus.

After an attempt to recanalize the left sigmoid sinus from the left internal jugular vein was unsuccessful, balloon dilation and Wallstent angioplasty of the occluded right transverse sinus were performed through the right internal jugular vein. Meanwhile, the embolism of DAVF was performed through the arterial approach. Postoperative angiography indicated restored antegrade blood flow with the disappearance of the fistula (Fig. 1 E, F). The patient reported that his symptoms had resolved and was discharged from the hospital. During the clinic follow-up visit 2 months later, the patient had no complaint, with a normal range of motions to 4 extremities and fluent speech.

DISCUSSION

Dural arteriovenous fistula, also known as DAVF-like vascular malformation, is a rare vascular disease that accounts for 10% to 15% of intracranial arteriovenous malformation (incidence rate is 0.15 to 0.16 cases/100,000 people/year).^1–3 Here, we report a case of DAVF (Cognard type III) in the left transverse–sigmoid sinus combined with occlusions at the distal, one-third of the left sigmoid sinus, and the proximal, 1/3 of the right transverse sinus, with the aim to improve our management of this rare disorder.

The underlying pathogenesis of DAVF is unknown. It is widely assumed that both innate and acquired factors play a role in the occurrence and progression of DAVF. It is widely assumed that both innate and acquired factors play a role in the occurrence and progression of DAVF. Tsai and colleagues advanced 2 hypotheses.⁴ One hypothesis is based on the physiological arteriovenous shunt between the meningeal arterial network and the dural sinus.⁵ When the pressure in the intracranial venous sinus rises, as in cerebral veno-sinus thrombosis (CVST), which blocks venous reflux, these channels may open and DAVF may form. Another theory is that, as demonstrated in Chen and colleagues’ rat model, venous hypertension caused by blocked venous return may reduce cerebral blood flow, resulting in cerebral ischemia, which leads to the formation of new blood vessels. Dural arteriovenous fistula is caused by abnormal angiogenesis in the dura mater.⁶

Whether there is a causal relationship between DAVF and sinus occlusions also requires further investigation. Risk factors for increased venous sinus pressure include venous sinus thrombosis, stenosis, or tumor compression, among others. At the outset, the cases discussed in this paper are left sigmoid sinus and right transverse sinus occlusion. The formation of bilateral CVST is clearly the cause of venous sinus pressure. Most CVST in patients with DAVF complicated by CVST is found in the venous sinus surrounding the DAVF or in the venous sinus in the DAVF’s downstream pathway. This finding supports the previously mentioned 2 hypotheses, namely that CVST causes venous hypertension and thus the formation of DAVF.⁴ Obviously, CVST does not always result in the formation of DAVF. The determining factor is whether intracranial venous hypertension forms. Moreover, according to some studies, the formation of CVST is secondary to DAVF, as the blood enters the vein through the fistula, the blood flow layer is destroyed into turbulence, and the intima of blood vessels may be destroyed, resulting in the formation of CVST.⁴ Due to the lack of imaging examination before onset, the causal relationship between DAVF and CVST is unknown, which needs further study.

Endovascular interventional therapy for DAVF includes arterial and/or venous embolization through the placement of coils and injection of microparticles or liquid embolic agents. Cognard classification and advanced treatment aim to eliminate cortical venous reflux and venous hypertension, and it is preferable to close the arteriovenous shunt. It can be seen from the related reports of the cases of the transverse sinus, sinus sigmoideus, and DAVF in the superior sagittal sinus area with ipsilateral CVST that the treatment goal has changed, opening the ipsilateral CVST to restore the normal venous blood flow direction, inserting or not inserting stents and assisting or not assisting transcatheter arterial embolization to improve intracranial venous hypertension.^7–10 Obviously, the opening of the obstructed venous sinus in the fistula region is the premise of the previously described treatment for these types of diseases. The case discussed in this paper is more complex than the one described previously. In addition to occluding the ipsilateral venous sinus, it also occluded the contralateral venous sinus. Right transverse sinus balloon angioplasty was performed and a self-expanding wallsten stent was implanted after a thorough evaluation and in accordance with the operative conditions. At the same time, the feeding artery of the fistula was embolized using an arterial approach. Angiography revealed that anterograde venous drainage had returned to normal, the fistula connection had essentially disappeared, and clinical symptoms had improved after the operation. The patient was discharged 6 days after surgery. The 2-month follow-up examination revealed that the patients experienced no obvious pain, normal physical activity, and fluent speech.

CONCLUSIONS

On the basis of our experience in this case, we concluded that (1) it is important to evaluate the satisfactory venous reflux in patients with DAVF at the transverse–sigmoid sinus, (2) it is also important to reestablish antegrade venous flow in patients with concurrent sinus stenosis or occlusion with DAVF, and (3) it is feasible and safe to simultaneously embolize DAVF after reestablishment of the venous reflux. We hope that our case presentation here could provide a new treatment approach to patients with similar clinical illnesses.