Flow diverter (FD) devices are new-generation stents placed in the parent artery at the aneurysmal neck to obstruct intra-aneurysmal blood flow, thus favoring intra-aneurysmal thrombosis. In Japan, about eight years have passed since health insurance approval was granted for FD devices, and FD placement to treat aneurysms has become widespread. Treatment indications have also been expanded with the introduction of novel devices. At present, three types of FD (Pipeline, FRED, and Surpass Streamline) are available in Japan. This report represents a compilation of available FD technologies and describes the current consensus on this treatment.

Treatment for wide-neck bifurcation cerebral aneurysms (WNBAs) is widely performed by endovascular treatment as well as open surgical clipping. However, due to factors such as the shape and size of the aneurysms, as well as the anatomical features of surrounding branch vessels, there are some cases in which simple coiling or conventional adjunctive techniques, such as balloon-assisted or neck bridge stent-assisted coiling, are not sufficient to achieve a satisfactory cure. Against this backdrop, the device known as the Woven EndoBridge (WEB) (MicroVention, Aliso Viejo, CA, USA) was developed and can be deployed directly into the aneurysm for treatment. Over a decade has passed since its development, and it is now used in many countries worldwide. This review provides insights into the evolution of the WEB device from its development to the date of this writing, highlighting the unique features of the device and its treatment indications. Additionally, it discusses the posttreatment course, perspectives on recurrence and retreatment, imaging assessments, and potential off-label use based on numerous studies primarily conducted in Europe and the USA.

Wide-neck bifurcation aneurysms (WNBAs) are sometimes challenging to treat. During endovascular treatment, it is important to prevent coil deviation and preserve normal vessels. Adjunctive balloon- and stent-assisted techniques have been developed. A meta-analysis of endovascular treatments of WNBAs revealed that only 40% of patients had complete occlusion. Recently, novel devices have been developed to expand the range of treatment options. Flow-diverter stents and intra-aneurysmal flow disruption devices do not require coils; however, coil embolization remains the standard procedure used by many neurointerventionists. This review describes the recent trends in adjunctive techniques for supporting coil embolization for WNBAs. We referred to literature on balloon-assisted techniques, stent-assisted techniques, Y-stenting, PulseRider, Barrel stents, Comaneci temporary stents, pCONUS, and eCLIPs. These reports showed that adequate embolization rates were generally greater than 80%, and the complete occlusion rate was as high as 94.6%. All devices had a relatively high occlusion rate; however, it may be inaccurate to simply compare each device because of the heterogeneity of the studies. It is important to select the best treatment for each individual case by considering not only literature-based efficacy and safety but also patient background, aneurysm characteristics, and operator experience.

Remarkable advances have been made in the endovascular treatment of intracranial cerebral aneurysms. These advances include various adjunctive techniques, increased indications for endovascular treatment, and improved treatment results. Furthermore, the number of cerebral aneurysm treatments using flow diverters (FDs) is expected to increase. However, the reported long-term rate of branch artery occlusion after FD treatment has been reported is 15.8%. Moreover, the complete aneurysm obliteration rate is low if normal branches arise from an aneurysm neck or dome. Flow diverter placement for ophthalmic artery, posterior communicating artery, and anterior choroidal artery aneurysms is often difficult because these normal branches often arise from the aneurysm neck or dome. Therefore, in many cases, coil embolization, which can occlude the aneurysm while preserving branch vessels, should be selected. Although not yet established, various adjunctive techniques and other endovascular treatments that can be performed safely have been reported. Treatment must be planned after understanding the advantages and disadvantages of each treatment method.

Intracranial artery dissections (IADs), although uncommon, are an important cause of cerebral infarction and subarachnoid hemorrhage (SAH). Some IADs can heal spontaneously after reconstitution of the vessel lumen with excellent prognosis. Meanwhile, others can progress to stroke that requires treatment. The incidence of IAD in the posterior circulation is higher than that in the anterior circulation. Anterior circulation dissections are more likely to develop into ischemia and posterior circulation lesions into hemorrhage. The mortality rate after IAD among patients with SAH is 19%–83%. Further, the mortality rate of IAD without SAH is 0%–3%.

Patients with SAH commonly undergo surgery or receive neuroendovascular treatment (EVT) to prevent rebleeding. However, the treatment of IADs is empirical in the absence of data from randomized controlled trials. Recently, EVT has emerged and is considered for IADs because of its less invasiveness and perceived low rates of procedure-related morbidity with good efficacy. EVT strategies can be classified into deconstructive (involving sacrifice of the parent artery) and reconstructive (preserving blood flow via the parent vessel) techniques. In particular, the number of reports on reconstructive techniques is increasing. However, a reconstructive technique for ruptured IADs has not yet been established. This review aimed to provide an overview of IADs in the posterior circulation managed with EVT by performing a literature search.