"Bonnet" bypass to proximal trunk of middle cerebral artery with a radial artery interposition graft: technical note

Anastomosis of the superficial temporal artery (STA) to the middle cerebral artery (MCA) is useful for treating certain patients with internal carotid artery occlusion or MCA occlusion. However, in the case of common carotid artery (CCA) occlusion, since the blood flow in the STA is insufficient, another artery should be used as the donor artery. The cortical branches of the MCA are usually selected as recipients in the STA-MCA bypass. However, the intracranial vascular filling gradually increases over a few months after conventional cortical MCA bypass grafting, while early or even immediate vascular filling is observed after proximal MCA bypass grafting. This study aims to develop an elongation technique of the contralateral STA to reach the proximal segment of the ipsilateral MCA.

Anastomosis of the contralateral STA to the secondary trunk of the ipsilateral MCA was performed in 2 patients with occlusion of the CCA and ipsilateral vertebral artery (VA). The contralateral STA was extended with a radial artery (RA) graft in order to supply blood to the ischemic area. Elongation of the STA by using an RA interposition graft sufficiently lengthens the graft to enable its anastomosis with the contralateral M2 segment. Postoperative imaging revealed good bypass patency even at 1 year after the surgery.

This novel technique of performing the "bonnet" bypass was effective in treating both CCA and ipsilateral VA occlusion; moreover, this procedure of elongation of the STA can increase candidates of the recipient, and enables one to perform a double bypass to the anterior cerebral artery (ACA) or posterior cerebral artery (PCA).