Increased Ratio of Superficial Temporal Artery Flow Rate After Superficial Temporal Artery-to-Middle Cerebral Artery Anastomosis: Can It Reflect the Extent of Collateral Flow?

There are several ways to identify donor artery patency and success of surgery after an anastomosis of the superficial temporal artery (STA) to the middle cerebral artery (MCA). The purpose of this study was to evaluate the ratio of bilateral STA mean flow rate (MFR) with the use of color Doppler ultrasonography (CDUS) after bypass surgery and to confirm the possibility of this value as a predictor of the extent of collateral flow.Eleven consecutive patients who had undergone STA-MCA anastomosis were included. In every case, bilateral STA MFR, mean velocity, and cross-sectional diameter were measured preoperatively and postoperatively at 1 week, 1 month, and 2 months via CDUS. We measured the bilateral STA MFR ratio changes to compensate for systemic hemodynamic variables.One month after surgery, 9 of the 11 patients who underwent STA-MCA anastomosis had good patency on DSA. In patients with good patency, there was a significant increase in the baseline STA MFR ratio compared with those at 1 week, 1 month, and 2 months postoperatively (2.88, 3.07, and 4.38, respectively, P0.05). The mean STA cross-sectional diameter ratio also was significantly increased postoperatively in the good patency group (1.35, 1.41, and 1.49, respectively, P = 0.044). In addition, the mean STA mean velocity ratio was increased postoperatively in the good patency group (1.48, 1.40, and 1.67, respectively, P = 0.042).We conclude that using CDUS to measure both STA MFR ratio is a potential method to predict the extent of collateral flow through an STA-MCA anastomosis.