Efficacy of venous blood flow monitoring during interhemispheric approach

Abstract

Interhemispheric approach is a common route for aneurysmal surgery, such as anterior communicating (A-com) artery and distal anterior cerebral artery (ACA) . There have been some attempts to preserve the bridging vein by mobilization or special dissection technique. Until now, there has been no intraoperative system for monitoring the venous blood flow. In the present study, we used microvascular Doppler sonography for venous blood flow velocity monitoring. Eleven cases of A-com aneurysm or distal ACA aneurysm were investigated in this study. Measurement of the venous blood flow velocity was performed at the following three different steps during the operation: before using the brain retractor (A), during brain retraction with the retractor (B), and after the operation (C) . We used two different techniques to dissect the bridging vein according to the severity of adhesion between the dura and the bridging vein. In 6 cases, the bridging vein was dissected free along the whole length between the cortex and superior sagittal sinus (SSS group) . In 5 cases, the vein was not dissected from the dura intentionally for a length of about 10 to 15 mm at its superior sagittal sinus side (dura group) .There was a strong tendency for decrease in the, venous blood flow velocity during brain retraction in the SSS group. The blood flow velocity was well preserved in the dura group. Two out of 6 cases in the SSS group showed venous occlusion on postoperative angiography and they developed transient or permanent neurological deficit.Our study revealed the importance of monitoring the venous blood flow velocity to minimize postoperative complications due to venous circulation disturbance.