Cerebral Cortical Blood Pressure Monitoring via STA-MCA Anastomosis for Safe Aneurysmal Surgery

Abstract

For surgery of giant or large cerebral aneurysm, we have used the intraoperative monitoring of cortical blood pressure to safely perform surgery and to get optimal clipping, when the risk of parent arteries stenosis caused by aneurysmal clipping may be higher. We report the merits and demerits of this method compared with usual methods for CBF monitoring such as ultrasonic Doppler flowmeter.
We studied 5 giant aneurysms and 3 large aneurysms by applying this method. In the 3 cases of giant aneurysm, high flow EC-IC bypass using radial artery (RA) free graft and ICA proximal ligation was performed. And in the other 2 cases, direct aneurysmal clipping under a temporary use of RA was employed. On the other hand, all 3 cases of large aneurysm had atheroscrelotic change in its wall. They were treated by direct clipping.
To monitor the cortical blood pressure, the following procedure was used. At first, we prepared two branches of superficial temporal artery (STA). After this, one of the branches was anastomosed to one of the branches of the middle cerebral artery (MCA) just distal to the aneurysm. Next, cannulation was performed into another branches of STA using a plastic needle, which was connected to a pressure transducer. By cutting off the blood flow from the main trunk of the STA, cortical blood pressure of the MCA was monitored through the bypass pathway.
Our study shows the differences between the two types of cases. In cases of direct clipping surgery, the change of cortical blood pressure indicated whether the parent artery was stenotic or not. And in cases of performing RA free graft bypass, it showed whether bypass flow could be used as a substitute for ICA flow or not. These results show it is easy to evaluate the direct blood pressure quantitively. In conclusion, this monitoring is considered a useful method to ensure safe surgery for patients with giant or large aneurysms.