Stent-assisted coil embolization of ruptured vertebral artery dissected aneurysm with severe stenosis of bilateral vertebral artery V4 segment by the transmountain technique: a case report and review of the literatures

Introduction

Vertebral artery dissecting aneurysms (VADA) are a critical cause of spontaneous subarachnoid hemorrhage (SAH), particularly among younger demographics. These lesions are highly unstable, with rebleeding rates reaching 70% and a high mortality rate. A recent case report in Frontiers in Surgery describes a complex scenario involving a 46-year-old woman with bilateral VADA and severe stenosis, managed through an innovative "Transmountain" endovascular technique.

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The Clinical Challenge

The patient presented with a ruptured aneurysm on the right vertebral artery and an unruptured, dilated dissection on the left. Both arteries also exhibited severe narrowing (stenosis) in the V4 segments. This "thorny" clinical problem ruled out standard "trapping" (vessel occlusion) due to the high risk of massive ischemic stroke. Furthermore, using multiple flow-diverter devices was deemed too costly and required aggressive anticoagulation that could jeopardize the patient's recovery from the initial hemorrhage.

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The Transmountain Approach

To address all four vascular issues simultaneously, surgeons employed the Transmountain technique. This endovascular strategy involves "bridging" the vertebrobasilar junction—the "mountain"—with a single long stent.

1. Navigation: A microguide wire was navigated through the right vertebral artery, across the confluence where the two arteries meet, and into the left vertebral artery.
2. Stent Deployment: A single 39mm Enterprise-2 stent was deployed across the junction. This low-mesh-density stent provided structural support without obstructing blood flow to critical branching vessels.
3. Multifunctional Intervention: The single stent served four purposes: it acted as a scaffold for coiling the ruptured right aneurysm, covered the unruptured left dissection, and mechanically dilated the severe stenosis in both the left and right arteries.
4. Coiling: Coils were then packed into the ruptured aneurysm through the stent mesh to prevent further bleeding.

Results and Clinical Significance

The procedure achieved immediate technical success, with over 95% occlusion of the ruptured aneurysm and significant relief of the bilateral stenosis. Clinically, the patient recovered well, showing normal speech and limb movement immediately post-operation. Follow-up imaging confirmed no new hemorrhages or strokes.

This approach highlights the philosophy that "simple is better." By using one device instead of several, the surgical team reduced operative time, minimized technical risks, and lowered the financial burden on the patient.

Conclusion

The Transmountain technique offers a promising, less invasive alternative for treating complex, multi-lesion vascular cases. While this case demonstrates excellent immediate results, the authors emphasize that long-term follow-up is necessary to monitor for potential re-narrowing (restenosis). Future multi-center studies will be essential to standardize this reconstruction strategy for patients with similar high-risk vascular anatomy.