Caudate haemorrhage caused by pseudoaneurysm of accessory middle cerebral artery

Abstract

A 68-year-old man experienced a right caudate haemorrhage with intraventricular haemorrhage. Although a subarachnoid haemorrhage was not shown clearly, our investigation demonstrated an aneurysm-like vascular pouch located in the anomalous vessel arising from the A2 segment of the right anterior cerebral artery. Rupture of the vascular pouch was considered to be the cause of the caudate haemorrhage. Neck clipping was performed. In intraoperative observation, the anomalous vessel was diagnosed as a right accessory middle cerebral artery. Histopathology of the saccular wall showed only an adventitia and a fibrin layer, indicating a pseudoaneurysm. We routinely perform detailed vascular evaluation for any cerebrovascular disease. A meticulous vascular survey makes it possible to obtain valuable clues in cases such as caudate haemorrhage due to pseudoaneurysm of the accessory middle cerebral artery, leading to prevention of rebleeding.

Figure 1

CT scans on the first admission showing a right caudate haemorrhage with intraventricular haemorrhage and subarachnoid haemorrhage, which was not clearly demonstrated (R, right).

Figure 2

Preoperative right internal carotid angiograms revealing a stenosis of the M1 segment of the right MCA; the anomalous vessel originated from the A2 segment of the right ACA with an aneurysm-like vascular pouch (ICA, right internal carotid artery; ACA, right anterior cerebral artery; MCA, right middle cerebral artery).

Figure 3

Intraoperative photograph showing a dark red wall on part of the vascular pouch, indicating partial thrombosis (Accessory MCA, right accessory middle cerebral artery).

Figure 4

Histopathological photomicrograph of the saccular wall demonstrating that the arterial layer was only an adventitia and a fibrin without intima, internal elastic membrane and media. H&E stain, magnification ×400.

Figure 5

Postoperative right internal carotid angiogram showing patency of the right accessory MCA and exclusion of the vascular pouch (ICA, right internal carotid artery; ACA, right anterior cerebral artery; MCA, right middle cerebral artery; Accessory MCA, right accessory middle cerebral artery).