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Published on: March 26, 2019
Sonographic Extracranial-Intracranial Bypass Monitoring: Technical Evolution and Current Evidence
1Department of Neurosurgery, NYU Grossman School of Medicine, New York, NY 10016, USA.
Insights
Trans-sonolucent cranioplasty ultrasonography (TCUS) offers direct, real-time visualization of extracranial-intracranial (EC-IC) bypass grafts. This radiation-free imaging method aids in monitoring graft patency and hemodynamic function post-surgery.
Area of Science:
- Neurosurgery
- Vascular Surgery
- Medical Imaging
Background:
- Extracranial-intracranial (EC-IC) bypass surgery is crucial for managing complex cerebrovascular diseases like chronic ischemia and aneurysms.
- Postoperative surveillance of graft patency and hemodynamic function is vital for successful EC-IC bypass outcomes.
- Sonographic imaging techniques for bypass monitoring have advanced significantly over four decades.
Purpose of the Study:
- To review the evolution of sonographic techniques for EC-IC bypass monitoring.
- To discuss the contemporary development and application of trans-sonolucent cranioplasty ultrasonography (TCUS).
- To evaluate TCUS as a reliable method for postoperative surveillance of EC-IC bypasses.
Main Methods:
- Review of historical and current sonographic imaging modalities for EC-IC bypass surveillance.
- Description of trans-sonolucent cranioplasty ultrasonography (TCUS) using polymethyl methacrylate (PMMA) cranioplasty.
- Analysis of existing evidence on TCUS reliability and comparison with digital subtraction angiography.
Main Results:
- TCUS allows direct, real-time visualization of bypass anastomoses and intracranial vasculature.
- This technique can be performed bedside or in outpatient settings, without radiation or contrast.
- Current evidence suggests TCUS is a reliable, potentially cost-effective complement to digital subtraction angiography for bypass surveillance.
Conclusions:
- TCUS represents a significant advancement in non-invasive postoperative surveillance of EC-IC bypass grafts.
- The technique offers advantages in terms of accessibility, safety (no radiation/contrast), and real-time assessment.
- Further prospective validation is needed to solidify TCUS's role in routine clinical practice for EC-IC bypass monitoring.
Abstract:
Extracranial-intracranial (EC-IC) bypass surgery remains an essential tool in the management of complex cerebrovascular disease, including chronic-ischemic hypoperfused territory as well as intracranial aneurysms requiring parent vessel sacrifice. Reliable postoperative surveillance of graft patency and hemodynamic function is central to long-term success. Sonographic imaging has evolved over four decades from indirect extracranial Doppler waveform analysis through intraoperative microvascular Doppler, quantitative duplex ultrasonography, and transcranial Doppler assessment of intracranial hemodynamics to the contemporary development of trans-sonolucent cranioplasty ultrasonography (TCUS). TCUS, enabled by the replacement of the autologous bone flap with an acoustically transparent polymethyl methacrylate (PMMA) cranioplasty, permits direct, real-time visualization of the anastomosis and surrounding intracranial vasculature. This can be performed at the bedside and in the outpatient setting, without radiation or contrast. Current evidence, drawn largely from small series and early multicenter experience, positions TCUS as a reliable and potentially cost-effective complement to digital subtraction angiography for serial bypass surveillance, though prospective validation remains needed. This review traces the full arc of sonographic bypass monitoring and addresses current evidence, technical considerations, established quantitative parameters, and directions for future investigation.
