To prospectively assess the feasibility and reliability of using microprobe vascular Dopple (MVD) to assess the vascular patency in patients undergoing superficial temporal artery to middle cerebral artery (STA-MCA) bypass procedure for Moyamoya disease (MMD).

From July 2012 to December 2017, 68 consecutive patients (totally 83 cases, including 15 cases who underwent bilateral surgeries) at Department of Neurosurgery, the First Affiliated Hospital of Soochow University, were confirmed to have MMD by digital subtraction angiography (DSA) and treated with STA-MCA bypass surgery. Before and after surgical revascularization, the hemodynamics parameters of the STA and the M4 segment of the MCA were evaluated by MVD. According to the STA pulsation index (PI) after the anastomosis, the patients were divided into three groups: patency group (n=57), PI≤1.10; poor patency group (n=17), PI>1.10; and obstruction group (n=9), the STA exhibited the "single peak" systolic blood flow signal. All patients underwent carotid Doppler ultrasonography (CDU), CT perfusion imaging (CTP), CT angiography (CTA), and DSA before and after surgery. The paired t-test was used to compare the hemodynamic parameters between the STA before and after anastomosis, between the M4 before anastomosis and the M4 proximal segment after anastomosis, and between the M4 before anastomosis and the M4 distal segment after anastomosis. The independent sample t-test was used to compare the hemodynamic parameters between the M4 proximal and distal segments after anastomosis. The differences of STA hemodynamic parameters among the patency group, the poor patency group, and the obstruction group were compared by the F test, and the statistically significant groups were further analyzed by the LSD-t test.

After the anastomosis, the blood flow velocity (Vm, Vs, and Vd) of the STA increased significantly and the PI decreased significantly (t=-5.32, -4.62, -5.68, 8.96, all P<0.001), and it showed an ″intracranial arterial spectrum″. When comparing among the three groups, the patency group had the highest blood flow velocity (Vm, Vs, and Vd) and the lowest PI (Vm: t=6.15; Vs: t=5.81, 6.95; Vd: t=7.32; PI: t=-11.99, -15.31; all P<0.001). The STA of all cases in the poor patency group and obstruction group were adjusted and corrected until the STA returned to an ″intracranial arterial spectrum″. After the anastomosis, the blood flow velocity (Vm, Vs, and Vd) of the MCA M4 proximal and distal segments increased significantly, and the PI of the distal segment increased significantly (proximal segment: t=-6.64, -7.73, -5.63; distal segment: t=-4.35, -4.51, -3.99, -3.96; all P<0.001). The blood flow velocity (Vm, Vs, and Vd) was significantly higher and the PI was significantly lower in the proximal segment than in the distal segment (t=2.58, 2.31, 2.69, 2.49, all P<0.05), and the blood flow direction in the proximal segment was reversed (indicating anastomotic patency). All patients underwent CDU in 4 to 7 days after surgery, and 95% (79/83) patients still presented an ″intracranial arterial spectrum″ in the STA, indicating that the anastomotic vessel was patent. This result was consistent with CTA findings, and CTP confirmed cerebral perfusion improvement as well. Between 6 months to 1 year after anastomosis, DSA confirmed that 96% (80/83) of anastomotic vessels were patent.

In STA-MCA bypass surgery, MVD can be ued to evaluate the patency of anastomotic vessels in real time, and PI≤1.10 can be used as a reliable indicator for judging vascular patency after STA anastomosis.