Effects of Superficial Temporal Artery Branch Management on Cerebral Bypass Blood Flow

Background and Objectives: Selected patients with moyamoya disease (MMD) and steno-occlusive cerebrovascular disease (SOCD) can benefit from bypass to augment cerebral perfusion. We have previously shown in a retrospective analysis that important variables for superficial temporal artery (STA)-to-middle cerebral artery (MCA) bypass flow include baseline penumbral volume as well as sacrifice of the non-donor branch of the STA. Building on this work, we herein assessed the real-time effect of non-donor STA branch occlusion on STA-to-MCA bypass flow using an ultrasonic flow probe.

Methods: This was a single-institution observational study of consecutive patients undergoing direct STA-MCA bypass with indirect encephalo-duro-myo-synangiosis for MMD and SOCD over 9 months. Patients with significant intracranial collateralization from the STA were excluded. The real-time effect of non-donor STA branch temporary occlusion on direct STA-MCA bypass flow was assessed using a Charbel flow probe. Patient characteristics and perioperative and postoperative outcome data were reviewed.

Results: Ten patients (4 MMD, 6 SOCD; mean age 56.3 ± 12.7 years) that underwent combined revascularization (4 left, 6 right) were included in the study. Upon serial analysis, mean donor STA branch flow increased from 4.91 ± 2.79 (baseline) to 17.75 ± 11.95 mL/minute after anastomosis (p = 0.015), presumably from release of the investing fascia on the distal artery, transection before downstream vessel narrowing and branch points that limit flow, fish mouthing of the donor STA combined with a generous arteriotomy of the recipient MCA, and connection to a low-resistance hypoperfused recipient vascular bed. Flow subsequently increased to 21.56 ± 11.01 mL/minute after the non-donor STA branch was test occluded (p = 0.005), which we hypothesized results from changes in flow dynamics, wherein blood is forced through the graft after the removal of a secondary outlet ([Fig. 1]). In 8 patients, the non-donor branches were subsequently sacrificed. The mean clamp time for anastomosis was 42.75 ± 8.78 minutes. Bypass patency was confirmed via intraoperative indocyanine green video angiography/Doppler ultrasound in all cases. The parietal STA branch was used as the donor in 8 (80%) cases. Perioperatively, one patient experienced transient dysarthria (10.0%); there were no strokes or other major complications. The median hospital length of stay was 5.0 (interquartile range: 3.0, 9.8) days, with 80% of patients discharged to home. Over a mean follow-up of 4.63 ± 2.45 months, no patients had significant wound healing issues, and the mean modified Rankin Scale score improved from 2.20 ± 1.14 preoperatively to 0.25 ± 0.46 (p < 0.001).

Conclusion: STA-MCA direct bypass flow may be optimized safely by sacrificing the non-donor STA branch in properly selected patients without STA-intracranial anastomoses.

Publication History

Article published online:
07 February 2025