Purpose Giant and big intracranial aneurysms are known often associated with cranial neuropathy due to mass effect. The purpose of our study was to compare clinical outcomes in patients with giant and big intracranial aneurysms of internal carotid artery treated by implantation of flow diverters and parent artery occlusion with bypass.

Methods Study of complex intracranial aneurysms treatment (SCAT) is open, prospective, parallel group, 1:1 trial with superiority design, conducted in 2 neurosurgical centers in Novosibirsk (Russia). After enrollment of 111 patients with complex intracranial aneurysms patients were distributed between 2 groups: flow diversion (55 patients) and PAO with bypass (56 patients). We included 38 patients with cranial neuropathy to determine the efficacy of procedures in regress of symptoms. The distribution of patients with cranial neuropathy was as follows: 17 patients in group of flow diversion and 21 in group of PAO with bypass. The presentation of symptoms was visual impairment (20 patients), oculomotor nerve palsy (8 patients) and abducens nerve palsy (10 patients). The aneurysms were located in cavernous carotid in 15 patients from bypass group and 10 ones from flow diversion group. Ophthalmic aneurysms were found in 5 patients on each group. Supraclinoid localization of aneurysm occurred in 2 patients from flow diversion group and in 1 patient from group of bypasses. The mean size of aneurysms accounted 21.54 mm.

Results Despite 100% occlusion rate on 12 months follow up in patients from bypass group, the treatment of aneurysms was associated with 3 hemorrhagic complications and 3 ischemic strokes. The morbidity in this group amounted 28.5%. Regress of cranial neuropathy was found in 8 out of 21 patients (38%). In contrast, complete occlusion occurred in 12 out of 17 patients (70.6%) from flow diversion group during 12 months follow up. There was one case of intraoperative rupture of giant cavernous aneurysms during implantation of flow-diverting stent. This carotid-cavernous fistula was managed in time and didn’t lead to unfavorable consequences for patient. The rate of complete resolution of cranial neuropathy in 12 months was 52.9% (9 out of 17 patients). After comparison with Chi-square test there was a lack of statistical significance between groups (p=0.3172).

Conclusion Treatment of big and giant intracranial aneurysms with flow diverting stents provides the same rate of complete resolution of cranial neuropathy as microsurgical treatment by PAO with bypass.

Disclosures R. Kiselev: None. A. Dubovoy: None. D. Kislitsin: None. A. Gorbatykh: None. A. Alshevskaya: None. K. Orlov: None.