Prerequisites for Clipping Surgery of Unruptured Intracranial Aneurysms of the Anterior Circulation: Indications, Surgical Strategy, and Technique

Abstract

Surgical clipping remains the gold standard for treating selected intracranial aneurysms regarding treatment durability, maneuverability of surrounding normal arteries, and certainty of bleeding control. Over the past 10 years, 663 procedures were performed in 629 patients with unruptured anterior circulation aneurysms. Neuroradiological images were thoroughly reviewed to evaluate the cerebrospinal fluid (CSF) space of the access route, venous drainage pattern, and surrounding structures, including perforating arteries, using constructive interference in steady state (CISS) magnetic resonance (MR) imaging and cerebral angiography to narrow down the indications for surgery in cases that met the following criteria: 1) ensuring operability to preserve normal vessels, especially perforating arteries; 2) the ability to secure both the proximal and distal vessels of the aneurysm, allowing precise control of blood flow; 3) comprehensive multidirectional visualization of the aneurysm; and 4) provision of sufficient angle and space for optimal clip application, including combinations of multiple clips. During surgery, preservation of the vein and avoidance of brain damage were top priorities, with the principle being to dissect the aneurysm circumferentially. However, if the perforating artery exhibited strong adhesions, aggressive dissection was not performed. No symptomatic complications were associated with the surgical procedures. Early postoperative MRI revealed diffusion-weighted imaging hyperintensity in the territories of the perforating branches in 5.4% of cases and T2 changes within the brain parenchyma in 20.8% of cases. Postoperative computed tomography angiography (CTA) showed no residual necks in 94.9% of cases, with residuals of 2 mm or less in 5.1%. During long-term follow-up of 371 patients (up to 10 years, average 6.4 years), no local recurrence of the aneurysm was observed. One of the important roles of direct aneurysm surgery is to provide a favorable long-term prognosis without surgical complications by limiting the indications to lesions that meet the above requirements.