Microsurgical Management of Posterior Circulation Aneurysms: A Retrospective Study on Epidemiology, Outcomes, and Surgical Approaches

Abstract

Posterior circulation aneurysms have been regarded as the most challenging for endovascular coiling and microsurgical occlusion. The role of microsurgical treatment is gradually being overlooked and diminishing in the trend of endovascular treatment. As microsurgical occlusion of posterior circulation aneurysms is decreasing, we present our relevant experience to evaluate treatment options and surgical approaches. A retrospective study was conducted in the Department of Neurosurgery of the First Affiliated Hospital of Soochow University between 2016 and 2021. Patients with posterior circulation aneurysms treated by clipping, bypass, and trapping were enrolled and followed up for at least six months. We included 50 patients carrying 53 posterior circulation aneurysms, 43 of whom had aneurysm ruptures. The posterior cerebral artery and posterior inferior cerebellar artery were the most common aneurysm locations. Direct clipping was performed in 43 patients, while bypass and trapping was performed in six patients. The retrosigmoid, far-lateral, and midline or paramedian suboccipital approaches were performed for those aneurysms in the middle and lower thirds. Aneurysms in the upper third required the lateral supraorbital approach, pterional approach, subtemporal approach, and occipital craniotomy. The lateral supraorbital approach was utilized in seven patients for aneurysms above the posterior clinoid process. Thirty-four patients recovered well with modified Rankin score 0-3 at discharge. No patient experienced aneurysm recurrence during the mean follow-up period of 3.57 years. Microsurgery clipping and bypass should be considered in conjunction with endovascular treatment as a treatment option in posterior circulation aneurysms. The lateral supraorbital approach is a feasible, safe, and simple surgical approach for aneurysms above the posterior clinoid process.

Keywords: lateral supraorbital approach; microsurgical occlusion; outcome; posterior circulation aneurysm; surgical approach.

Figure 1

The distribution of modified Rankin Scale at admission, discharge, and six months. Shown are the percentages of patients at admission, discharge, and six months with scores from 0 to 6 on the modified Rankin scale.

Figure 2

A woman with a saccular aneurysm on the bifurcation of the right superior cerebellar artery (SCA) and the basilar artery (BA). (A) The computed tomography scan showed no apparent abnormality; (B) The computed tomography angiography (CTA) revealed a 3 mm saccular aneurysm on the bifurcation of the right SCA and the BA; (C) Preoperative simulation of the surgical approach; (D) The aneurysm, SCA, and BA before clipping; (E) The aneurysm, SCA, and BA after clipping; (F) Intraoperative indocyanine green videoangiography confirmed no residual aneurysm and patency of SCA and BA; (G) Postoperative CTA further demonstrated complete obliteration of the aneurysm; (H) The small bone flap. (The yellow arrows show the aneurysm, and the blue arrows show the SCA).

Figure 3

A woman with a large saccular aneurysm on the V4 segment of the right vertebral artery (VA), a small saccular aneurysm on the C7 segment of the left internal carotid artery (ICA), and a fusiform aneurysm located in the V3 segment of the left VA. (A) The CT scan showed a round-like mass located in the front of the medulla oblongata; (B) The digital subtraction angiography (DSA) and CTA disclosed a large saccular aneurysm located in the V4 segment of the right VA, a small saccular aneurysm located in the C7 segment of the left internal carotid artery, and a fusiform aneurysm located in the V3 segment of the left VA; (C) The aneurysm, VA, and posterior inferior cerebellar artery (PICA) before clipping; (D) The aneurysm, VA, and PICA after clipping; (E) Intraoperative indocyanine green videoangiography confirmed no residual aneurysm and patency of VA and PICA; (F) Postoperative CTA further demonstrated complete obliteration of the aneurysm. (The yellow arrows show the aneurysm, and the blue arrows show the PICA).