Threading the needle: Intrasaccular WEB device for the treatment of a basilar fenestration aneurysm

• Normally fit and well 47-year-old presented with sudden onset thunderclap occipital headache, which started 9 days prior and was ongoing.
• Clinical team requested CT head and CT angiogram due to a concern regarding subarachnoid haemorrhage.
• CT showed no acute haemorrhage, but CT angiogram demonstrated a vertebrobasilar junction aneurysm.

What next?

• Endovascular embolisation as inpatient
• Book in neurovascular clinic
• Neurovascular MDT referral
• Lumbar puncture
• Surgical clipping as inpatient

• Lumbar puncture was performed to rule out SAH, as evidence of rupture would necessitate acute treatment of the aneurysm. This was performed on the day of admission.
• The LP demonstrated increased CSF bilirubin consistent with SAH.
• Treated as late presentation of a ruptured aneurysm. Endovascular treatment was the preferred method, with patient going for treatment the following day.

DSA

Following the initial DSA and 3D, decision was made to treat with a WEB device.
Note the anteriorly pointing bleb that is the presumed rupture point.

Average height = 6.5 mm
Average width = 6.5 mm

Management

• GA. 6-French access. Co-axial system.
• Benchmark/MPA/Terumo used to access the left VA for angiography and 3D.
• Via 27/ Synchro used to cannulate aneurysm. WEB 8 x 4mm device deployed through Via 27.
• Minimal protrusion of WEB towards the left side of the parent vessel of the fenestration. 5-minute delayed angiogram did not show any thrombus build up.

Web sizing

• We generally adopt +1 width and -1 height for WEB sizing if aneurysm shape is cylindrical.
• This aneurysm was not completely cylindrical (slightly rounded), so we opted to -2 from the height to prevent excess protrusion of WEB through the neck.
• As you can see from the final check angiogram, a good result was achieved and the anterior pointing bleb (presumed rupture point) occluded immediately.
• Patient was treated recently, so no follow-up imaging is currently available.

Discussion

• Fenestration of the Basilar artery is a result of incomplete fusion of the longitudinal neuronal arteries. This leads to two lumens forming.
• These aneurysms can present a treatment challenge due to their complex morphology and location adjacent to the eloquent brainstem.
• Endovascular management provides a safe and effective treatment method. The WEB device is ideally suited and reduces the need for balloons, assist devices or stents. This reduces the risk of complications and dispenses with the need for antiplatelet therapy.
• Our patient was successfully treated with a WEB device and discharged within one week of the acute treatment. Follow-up imaging at 6 months and 24 months is awaited.
• To our knowledge, there have been three reported cases in the literature of fenestrated basilar aneurysms treated with a WEB device.

References

• Chew, H. S., Chong, M. Y., Butt, W., Al-Ali, S., Butler, B., Al-Tibi, M., ... & Lamin, S. (2024). Lateral Compression Manipulation: A Simple Approach for Sizing Taller-Than-Wide Intracranial Aneurysms with the Woven EndoBridge Device. American Journal of Neuroradiology, 45(6), 731-736.
• Mansouri, A. M., Mandoura, W. O., Alharbi, J. K., Alsharif, R. A., Alharbi, N., Mansouri, A., & Alsharif, R. (2025). Basilar Artery Fenestration Aneurysm Treated With the Woven EndoBridge (WEB) Device: A Case Report and Review of the Literature. Cureus, 17(3).
• de Almeida Silva, J. M., Dias, G. M. S., & Rezende, A. L. (2021). Basilar artery fenestration aneurysm treated with the Woven EndoBridge device. Interdisciplinary Neurosurgery, 23, 100936.

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