On Flow Diversion: The Changing Landscape of Intracerebral Aneurysm Management

Uptake of flow-diverting technology is rapidly outpacing the availability of clinical evidence. Most current usage is off-label, and the endovascular community is nearer the beginning than the end of the learning curve, given the number of devices in development. A comprehensive overview of technical specifications alongside key outcome data is essential both for clinical decision-making and to direct further investigations. Most-studied has been the Pipeline Embolization Device, which has undergone a transition to the Pipeline Flex for which outcome data are sparse or heterogeneous. Alternative endoluminal devices do not appear to be outperforming the Pipeline Embolization Device to date, though prospective studies and long-term data mostly are lacking, and between-study comparisons must be treated with caution. Nominal technical specifications may be unrelated to in situ performance, emphasizing the importance of correct radiologic sizing and device placement. Devices designed specifically for bifurcation aneurysms also lack long-term outcome data or have only recently become available for clinical use. There are no major studies directly comparing a flow-diverting device with standard coiling or microsurgical clipping. Data on flow-diverting stents are too limited in terms of long-term outcomes to reliably inform clinical decision-making. The best available evidence supports using a single endoluminal device for most indications. Recommendations on the suitability and choice of a device for bifurcation or ruptured aneurysms or for anatomically complex lesions cannot be made on the basis of current evidence. The appropriateness of flow-diverting treatment must be decided on a case-by-case basis, considering experience and the relative risks against standard approaches or observation.