Unusual Synchronous Arbitrary-Gate Doppler Spectra Enable Intraoperative Hemodynamic Warning of Cerebral Hyperperfusion Syndrome on Moyamoya Disease.

BACKGROUND

Cerebral hyperperfusion syndrome (CHS) is a serious complication following revascularization in moyamoya disease (MMD) patients, yet reliable predictors remain scarce. This study aims to evaluate subcortical hemodynamics intraoperatively using a novel ultrasound imaging technique, synchronous arbitrary gate spectral Doppler (SAGSD), and to identify indicators associated with CHS.

METHODS

A total of thirty adult MMD patients undergoing revascularization were included. Intraoperative SAGSD imaging, conventional Doppler ultrasound, and indocyanine green videoangiography (ICG-VA) were performed to assess subcortical hemodynamics at multiple sites before and after anastomosis.

RESULTS

All thirty patients underwent revascularization, and five of the six CHS patients exhibited a distinctive "mountain" sign on SAGSD, characterized by three or more discrete velocity peaks within a single cardiac cycle observed simultaneously across two or more sampling sites. The CHS patients showed a significant increase in velocity-time integral (VTI) change (median Δ + 0.48 cm [95% CI, 0.31 to 0.65], p < 0.001) post-anastomosis on SAGSD, while conventional Doppler showed no significant change in flow velocity (all p > 0.05). Notably, in CHS patients, ICG-VA showed no statistical difference in flow velocity, delay, and time to peak after anastomosis (all p > 0.05), whereas SAGSD demonstrated hemodynamic changes such as VTI (median Δ + 0.67 cm [95% CI, 0.43-0.90], p < 0.001) via Doppler spectrum.

CONCLUSION

SAGSD enables highly sensitive, multi-position, and contrast-free hemodynamic evaluation of deep cerebral microvasculature. The "mountain" sign, a novel spectral morphology corroborated by quantitative VTI elevation, is a specific intraoperative biomarker strongly associated with CHS, offering a potential predictor for early intervention and improved surgical outcomes.