Trans-sonolucent Cranioplasty Ultrasonography for Long-Term Superficial Temporal Artery-Middle Cerebral Artery Bypass...

Trans-sonolucent cranioplasty ultrasonography (TCUS) has been explored as a noninvasive tool for evaluating superficial temporal artery (STA)-middle cerebral artery (MCA) bypass patency. Previous research has focused on early postoperative feasibility. Data on its long-term utility and correlation with formal angiography remain scarce. We aimed to evaluate TCUS' role in postoperative STA-MCA bypass graft monitoring and its concordance with formal angiography.

This retrospective study included 46 consecutive direct STA-MCA anastomoses in 40 patients (March 2021-May 2024), all with sonolucent polymethyl methacrylate cranioplasty. Patient records were reviewed for demographics, disease and surgical characteristics, and outcomes. Postoperative TCUS was performed outpatient to monitor anastomotic patency. Formal follow-up angiography was also conducted, and radiographic data were reviewed for graft patency assessment and qualitative correlation with TCUS.

Follow-up angiography was performed for 41 of 46 anastomoses (digital subtraction angiography, n = 34; computed tomography angiography, n = 4; magnetic resonance angiography, n = 3) at a median of 1.1 years, demonstrating 97.6% patency (40/41). Outpatient TCUS was performed in 32 of 46 bypasses (69.6%) with 100% patency at first scan (median 28.5 days). A second TCUS (n = 19, 41.3%) at a median of 8.4 months (3.9-13.6 months) showed robust flow in 94.7% of cases. One bypass had asymptomatic slow flow with a narrowed anastomosis, and another showed a severely stenosed STA correlating with later digital subtraction angiography. In the broader cohort, third (n = 5, median 1.2 years) and fourth (n = 1, 1.4 years) TCUS assessments demonstrated 100% patency. Among bypasses undergoing both TCUS and angiography (n = 31, 67.4%), findings were concordant in all cases.

TCUS demonstrated complete agreement with formal angiography in assessing bypass patency, supporting TCUS as a reliable, noninvasive monitoring tool. Future research should explore quantitative TCUS flow measurements and their relationship to intraoperative flow and long-term graft remodeling.