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.
