As the utilization of flow diverting technology has become more widely accepted, so have the indications. The authors1 provide us with a sustained review of available information and some nice case examples of flow diversion used to treat lesions that were not initially “on label” for the devices. The title provides us with a nice framework on which to think about lesions that are treated off label. As we moved further from the circle of Willis, smaller flow-diverting devices are needed to treat aneurysms. The authors describe these newer smaller devices well. We anticipate more work in the future in this area in terms of a wider breadth and the type of flow-diverting devices available for more distal aneurysms. With ease of utilization, we are seeing smaller aneurysms treated with flow diversion. The efficacy of this type of treatment can be quite high for small sidewall aneurysms. If indeed the risks of these treatments are lower, one may consider a more aggressive posture for smaller intracranial aneurysms in younger individuals, which do have the potential for hemorrhage over the remainder of the individuals’ lifetime.
The authors describe the use of flow diversion to treat remnants of aneurysms or recurrences in situations of previously coiled or previously clipped aneurysms. These remnants or regrowths were often left untreated because of the perceived risks involved with the treatment with an unknown natural history. Flow diversion offers the possibility of treatment with low risks and indeed a relatively high chance of lesion obliteration. Based on the authors’ presentation, flow diversion can certainly be considered in these clinical situations. In terms of flow diversion for the treatment of carotid-cavernous fistulas, more work is needed in this area. The occlusion rates are still relatively low, although the symptom improvement is reported as 71% in the largest number of patients reported to date. An adjunct of devices such as coils or embolic material in the fistula may be needed in addition to flow diversion for complete obliteration. The authors’ discussion sets the stage for this type of investigation. As the authors point out, these are exciting areas of new frontiers for aneurysm treatment.
Outside of publication in this supplement, the author has no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.
1. Limbucci N, Leone G, Renieri L, et al. Expanding indications for flow diverters: distal aneurysms, bifurcation aneurysms, small aneurysms, previously coiled aneurysms and clipped aneurysms, carotid cavernous fistulas. Neurosurgery. 2020;86(1 suppl):S85-S94.