Rupture of a large vertebral artery aneurysm following proximal occlusion

Abstract

Proximal occlusion of the vertebral artery is regarded as a safe and effective method of treating aneurysms of the vertebral artery or the vertebrobasilar junction unsuitable for treatment by neck clipping. Complications known to develop after this procedure include ischemic lesions of the perforators and other areas. There are only a limited number of reports on early rupture of aneurysm following proximal occlusion of the vertebral artery for the treatment of unruptured aneurysm. We recently encountered a case of large aneurysm of the vertebral artery identified after detection of brainstem compression. This patient underwent proximal occlusion of the vertebral artery with a coil and developed a fatal rupture of the aneurysm ten days after proximal occlusion. The patient was a 72-year-old woman who had complained of dysphagia and unsteadiness for several years. An approximately 20 mm diameter aneurysm was detected in her left vertebral artery. She underwent endovascular treatment, that is, her left vertebral artery was occluded with coils at a point proximal to the aneurysm. Her initial post-procedure course was uneventful. However, she suddenly developed right-side hemiparesis nine days after procedure. At that time, CT scan suggested sudden thrombosis of the aneurysm. Right vertebral angiography revealed a small part of the aneurysm. She was treated conservatively. Ten days after the procedure, she suffered massive subarachnoid haemorrhage. Both the present case and past reports suggest that proximal occlusion of the vertebral artery is effective in treating relatively large aneurysms unsuitable for treatment by neck clipping or trapping. However, when the bifurcation of the posterior inferior cerebellar artery (PICA) is distal to the occluded point in cases where the PICA bifurcates from the aneurysm or the neck region, blood supply to the aneurysm may persist because anterograde blood flow to the PICA may be preserved. Therefore, clinicians must consider the possibility of aneurysm rupture after proximal occlusion in the following cases: 1) when the aneurysm is large or giant, but non-thrombosed; 2) when thrombosis occurs soon after the procedure; 3) when postoperative angiography shows partial filling of the aneurysm with contrast agent through the contralateral vertebral artery of basilar artery or the cervical muscle branches.

Figure 1

A) FLAIR axial MR image shows large aneurysm with a diameter of 20 mm with turbulent flow. B) T1-weighted sagittal image shows marked compression of brainstem, but no thrombus in the aneurysm.

Figure 2

Left vertebral angiography. Anteroposterior (A) lateral (B) and oblique (C) views show the PICA originating from the proximal neck of the aneurysm. The distance from the distal neck to union of the aneurysm was 2 to 3 mm.

Figure 3

Immediate post-proximal occlusion angiographies show no filling of the left vertebral artery aneurysm from either the left vertebral artery (A) or contralaterally from the right vertebral artery (B).

Figure 4

Noncontrast axial CT scan nine days after proximal occlusion shows extensive thombus filling the aneurysmal sac.

Figure 5

Right vertebral angiography ten days after proximal occlusion. Anteroposterior (A) and lateral (B) views show small retrograde filling of the aneurysm.

Figure 6

Noncontrast axial CT scan ten days after proximal occlusion shows massive subarachnoid haemorrhage.