The field of neuro-intervention has made significant advances in the last decade and several new devices have been developed to treat aneurysms. These devices include flow diverters, intrasaccular devices, to complement more conventional tools (i.e. balloons, stents, and coils). The WEB device (MicroVention/Terumo) has been used to treat bifurcation aneurysms with good results. While long-term success/occlusion rates of this device remains to be seen, it has demonstrated a high technical success rate. We describe an unusual case of delayed collapse of a WEB device deployed in a large basilar apex aneurysm with initial technical success.   

A 56 year-old woman with type 2 diabetes mellitus & hyperlipidemia presented to the emergency room with new onset diplopia & dysarthria. Initial neuroimaging revealed a 13.7 mm x 10.4 mm x 7.3 mm basilar apex aneurysm. MRI Brain without contrast revealed significant vasogenic edema involving the midbrain & upper pons. Patient underwent successful endovascular deployment of a WEB SLS 11 x 9.6 mm device with excellent wall opposition & contrast stagnation in the aneurysm sac, without residual filling of the base & lateral walls. Additional treatment with corticosteroids resulted in near complete symptom resolution. Follow up angiography after 7 months revealed a largely collapsed WEB device into the aneurysm's distal dome with a large residual aneurysm (11.5 mm x 9.5 mm x 8.5 mm). After extensive discussion with the patient, retreatment consisted of deployment of a PCA-PCA stent via the Left Posterior communicating artery & coiling into the residual aneurysm. Patient remained asymptomatic & was discharged on dual antiplatelet therapy (Aspirin, Clopidogrel), oral methylprednisone taper & outpatient follow up. 

This case highlights the potential complications of WEB device placement in large aneurysms. To our knowledge, this is the first reported case of delayed WEB device collapse for a basilar apex aneurysm. Further research is needed to identify the root cause.