Despite the active development of surgical methods of treatment (endovascular embolization and microsurgical clipping) of cerebral aneurysms, determining the indications and method of surgical treatment of cerebral aneurysms still causes debate in many cases. To a greater extent, this concerns the treatment of unruptured aneurysms. While there are a number of randomized trials of surgical treatment of ruptured cerebral aneurysms, there is currently no published randomized trial comparing surgical clipping and endovascular embolization of unruptured aneurysms. The purpose of this study is to compare the safety and efficacy of microsurgical clipping and endovascular embolization of cerebral aneurysms (both ruptured and unruptured) in a prospective, randomized fashion.

The study is planned to include 200 patients. Before randomization, patients will be stratified according to the presence or absence of aneurysm rupture in the acute period. The stratified patients will be randomized into two groups (100 to the microsurgical clipping group and 100 to the endovascular embolization group). Each group will be divided into 2 subgroups of 50 people each: the first subgroup includes patients in the acute period of aneurysm rupture, the second subgroup includes patients with unruptured aneurysms. Patients will be followed postoperatively, outcome endpoints will be assessed at discharge, 6 and 12 months. At discharge and after 6 and 12 months, patients will be assessed clinically using a modified Rankin scale (mRS). Cerebral angiography will be performed intraoperatively (endovascular group), after surgery (microsurgical group) and 12 months after discharge (both groups). Thus, the outcome of surgical treatment, including periprocedural complications and mortality, will be assessed both clinically and angiographically.

Inclusion Criteria:

• Patients with ruptured (acute SAH) or unruptured cerebral aneurysm who require surgical treatment (clipping and / or embolization)
• Both male and female
• Age from 18 to 80 years
• Informed consent to participate in the study signed by the patient. If the patient cannot give consent, informed consent is signed by closest relatives or based on the results of a medical concilium
• The patient (legal representative) agrees to a clinical assessment (examination and / or telephone visit) within 6 months and 12 months and to an angiographic control after 12 months
• Patient has not previously been randomized to this or other ongoing study
• Aneurysm has not previously been treated with endovascular embolization or microsurgical clipping

Exclusion Criteria:

• The target aneurysm has been treated (embolization or clipping) before
• Severe clinical condition of the patient (Glasgow coma scale <4, unstable hemodynamics)
• Lack of signed informed consent
• Severe medical or surgical comorbidity in which the patient's life expectancy is less than 2 years
• Pregnancy, breastfeeding