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|LETTER TO EDITOR
|Year : 2020 | Volume
| Issue : 3 | Page : 708-709
Vertebrobasilar Junction Aneurysm Associated with Subclavian Steal: Yet another Hemodynamic Cause for Aneurysm Development and Associated Challenges
Chirag Kamal Ahuja1, Manisha Joshi1, Sandeep Mohindra2, Niranjan Khandelwal1
1 Department of Radiodiagnosis and Imaging, Post Graduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh, India
2 Department of Neurosurgery, Post Graduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh, India
|Date of Web Publication||6-Jul-2020|
Dr. Chirag Kamal Ahuja
Department of Radiodiagnosis and Imaging, Post Graduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Ahuja CK, Joshi M, Mohindra S, Khandelwal N. Vertebrobasilar Junction Aneurysm Associated with Subclavian Steal: Yet another Hemodynamic Cause for Aneurysm Development and Associated Challenges. Neurol India 2020;68:708-9
|How to cite this URL:|
Ahuja CK, Joshi M, Mohindra S, Khandelwal N. Vertebrobasilar Junction Aneurysm Associated with Subclavian Steal: Yet another Hemodynamic Cause for Aneurysm Development and Associated Challenges. Neurol India [serial online] 2020 [cited 2021 May 5];68:708-9. Available from: https://www.neurologyindia.com/text.asp?2020/68/3/708/288981
Vertebrobasilar junction (VBJ) aneurysms are rare with reported incidence being approximately 0.5% of all treated aneurysms. Surgical access of such aneurysms is difficult due to complex anatomy and adjoining vital structures; endovascular treatment is usually the treatment of choice in these cases. There has been only few reports of subclavian steal phenomenon as the contributory factor for VBJ aneurysms, emphasizing the hemodynamic etiology for the aneurysm development.
We report a rare case of ruptured VBJ aneurysm with asymptomatic subclavian steal phenomenon, treated with endovascular coiling. A 70-year-old female with no known comorbidities presented with sudden onset headache and transient loss of consciousness. Noncontrast computed tomography head showed Fisher grade IV subarachnoid hemorrhage. World Federation of Neurological Surgeons grade was I and Hunt and Hess grade was II at presentation. Computed tomography angiography of the cerebral vessels showed a saccular aneurysm arising from right lateral wall of the VBJ near the origin of right anterior inferior cerebellar artery (AICA). Diagnostic digital subtraction angiography showed that right subclavian artery was completely occluded at its origin with reversal of flow in right vertebral artery (VA) and saccular aneurysm at the VBJ [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d and [Figure 2]a. Direction of the aneurysm at VBJ supports the hemodynamic stress as the etiology of aneurysm development [Figure 2]b. There was no definite history of symptoms attributable to subclavian steal. Endovascular coil embolization was planned. Through right femoral artery access, a 6F guiding catheter (Neuron, Penumbra Inc.) was positioned in V3 segment of left VA through which a 1.7-F microcatheter (Echelon, ev3, Irvine, California, USA) was navigated into the aneurysm [Figure 2]c over a 0.014-inch microguide wire (Traxcess, MicroVention, Tustin, CA, USA). Microcatheter navigation into the contralateral VA was thought to present a challenge. However, due to the reversal of blood flow (yellow arrows in [Figure 2]b, there was a tendency of the guidewire to “flow” toward the aneurysm neck. Catheterization of the aneurysm was, therefore, achieved fairly easily. Platinum coils were deployed in the aneurysm sac and complete occlusion of the aneurysm sac was achieved. A tiny thrombus was noted at the VBJ adjacent to the aneurysm neck postprocedure [Figure 2]d, which was completely lysed following intra-arterial administration of 2-mg abciximab directed at the thrombus. The patient was subsequently discharged after 10 days in the premorbid state and was doing well at 1 month follow-up.
|Figure 1: PA view angiographic runs of brachiocephalic artery (a) and left VA (b) showing complete occlusion of the right subclavian artery at origin (red cross) and flow reversal in the right VA (represented by yellow arrows). Composite angiographic image (c) showing the level of brachiocephalic artery block (black arrow and red slab). Pictorial reconstruction of the distal subclavian artery and VA has been done depicting the blood flow, and arterial opacification had the occlusion not been present. 3D rotational angiography (d) showing VBJ aneurysm adjacent to right AICA origin|
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|Figure 2: Left vertebral angiography demonstrating the VBJ aneurysm (a) with yellow arrows showing the blood flow direction and relation of aneurysm location with flow direction (b). Microcatheter has been positioned within aneurysm sac (c). Postcoiling angiogram (d) revealing complete aneurysm occlusion with a tiny thrombus at aneurysm neck (white arrow), which was subsequently lysed with intra-arterial abciximab|
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Fenestration at the VBJ is a rare but known cause of aneurysm development in that location compromised by hemodynamic stress. Subclavian steal leads to redirection of blood from the contralateral VA to the ipsilateral subclavian artery in an attempt to perfuse the upper limb. This causes increased hemodynamic stress at the VBJ, where the blood flow vector is directed at the opposing wall. As a result it is prone to aneurysm formation ,, further strengthening the hemodynamic theory as an important risk factor for aneurysm development. Following are few additional points worth highlighting in this specific situation:
- As the direct ipsilateral access to the aneurysm is blocked, either prior treatment of subclavian stenosis is required before the aneurysm treatment or a contralateral approach needs to be taken (which was feasible in the present case). The contralateral approach, in fact, provided a straighter and direct access into the aneurysm inflow zone.
- If contralateral VA approach is taken, extra vigilance is required as it is a precious artery supplying the entire infratentorial posterior circulation as well as the contralateral upper limb.
- Catheterization of the aneurysm in the contralateral limb may be challenging due to the reverse path that has to be taken. An exaggerated curve of the microguidewire often helps in cannulating the contralateral VA. Subsequent navigation toward the V3 vertebral segment is aided by the blood flow. The microcatheter should be threaded over the wire till beyond the aneurysm neck. Gentle withdrawal of the catheter leads to falling of the tip into the neck and subsequent aneurysm catheterization. A gentle curve on the microcatheter tip helps to achieve this.
In conclusion, subclavian steal with VBJ aneurysm is a rare occurrence re-emphasizing shear stress as a causative factor for aneurysm development. It can be effectively managed by endovascular coiling.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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