Current Treatment Modalities for Wide Necked Intracranial Aneurysms

The prevalence of intracranial aneurysms in the adult population is estimated to be around 2 %. Most remain asymptomatic, but there is a risk of rupture of 1.2 % per year, and this risk increases in line with the diameter of the aneurysm. If rupture occurs, subarachnoid hemorrhage and its associated acute complications are responsible for high mortality (between 30 and 67 %) and morbidity (between 15 and 30 %).

Coil embolization of intracranial aneurysms has made remarkable technological progress since the International Subarachnoid Aneurysm Trial (ISAT) data were released in 2005. However, wide-necked aneurysms remain a great challenge to be treated via the endovascular means, as they are associated with a significantly greater incidence of adverse events when compared with narrow-necked ones.

Acutely ruptured wide-necked intracranial aneurysms pose technical challenges to the treating physician; thus, multiple endovascular techniques have been described to treat these lesions, including balloon-assisted coil placement, double microcatheter technique, and microcatheter assisted coil placement. However, the use of these techniques can sometimes be limited, owing to the lack of permanent support for the coil mass inside the aneurysm sac, which may lead to coil prolapse or migration after the procedure, especially for wide-necked aneurysms (dome-to-neck ratio is less than 1) or tiny aneurysms (3 mm). Therefore, surgical clipping is preferred for acutely ruptured wide-necked intracranial aneurysms in most institutions. Surgery, however, may also be challenging in some of these lesions, since clips may slip, and surgical access may be limited because of the swelling of the brain in the acute setting of a subarachnoid hemorrhage.

Flow diverters are new implantable medical devices that make possible to embolize wide-necked aneurysms without the use of coils; the efficacy results published to date are encouraging in terms of complete occlusion in the medium-term, thereby confirming the innovative nature of the flow diversion technique that we aim to evaluate without the use of coils.