Abstract
We performed this study to elucidate whether or not the extent of the bypass flow through superficial temporal artery-to-middle cerebral artery (STA-MCA) anastomosis could be indirectly estimated by measuring the blood flow velocity in the STA using duplex ultrasonography. We analyzed 32 patients (35 sides) who underwent STA-MCA bypass surgery for occlusive cerebrovascular disease. The flow velocities of the STA were measured by ultrasonography. For the patients who underwent the surgery unilaterally, the flow velocity ratios of the operated side to the contralateral side were calculated. The correlation between these flow velocity parameters and the extent of the bypass flow, which was graded based on the findings of cerebral angiography, was investigated. Both the affected STA flow velocity and the STA flow velocity ratio, particularly those in end-diastole, increased in patients with more extensive bypass flow. In patients with extensive, moderate and poor bypass flow, the end-diastolic flow velocities (EDV) of the operated STA were 32.0±17.4, 24.9±9.5 and 13.5±7.5 (cm/sec), respectively and the EDV ratios of the STA were 3.4±0.7, 2.2±0.5 and 1.3±0.4, respectively. The optimal threshold value of the EDV ratio of STA for the extensive group was 2.7 while that for the poor group was 1.6. With the obtained values, the sensitivity and specificity were 88.9% and 91.4% for the extensive group, and 95.8% and 95.0% for the poor group, respectively. The blood flow velocity in the operated STA appeared to be a highly sensitive parameter for predicting the extent of the bypass flow in patients undergoing STA-MCA anastomosis.
