Application of Indocyanine Green During Arteriovenous Malformation Surgery: Evidence, Techniques, and Practical Pearls

Abstract

Indocyanine green (ICG) is a fluorescent molecule that enables visualization of hemodynamic flow through blood vessels. The first description of its application to the resection of arteriovenous malformations (AVMs) did not occur until 2007. Since then, industry leaders have rapidly integrated this optical technology into the intraoperative microscope, and the use of ICG videoangiography (VA) has since become routine in AVM surgery among some academic centers. A number of case series have been published since the introduction of ICG VA to AVM neurosurgery. These early reports with small sample sizes were largely qualitative, assigning to the technology "usefulness" and "benefit" scores as perceived by the operators. This lack of objectivity prompted the development of FLOW 800 software, a proprietary technology of Carl Zeiss Meditec AG (Oberkochen, Germany) that can quantify relative fluorescence intensity under the microscope to generate color maps and intensity curves for ad hoc and post hoc analyses, respectively. However, subsequent case series have done little to quantify the effect of ICG VA on outcomes. The available literature predominately concludes that ICG VA, although intuitive to deploy and interpret, is limited by its dependence on direct illumination and visualization. The subcortical components of AVMs represent a natural challenge to ICG-based flow analysis, and the scope of ICG VA has therefore been limited to AVMs with a high proportion of superficial angioarchitecture. As a result, digital subtraction angiography has remained the gold standard for confirming AVM obliteration. In this review, we provide an overview of the existing literature on ICG VA in AVM resection surgery. In addition, we describe our own experiences with ICG VA and AVMs and offer the senior author's surgical pearls for optimizing the marriage of fluorescence flow technology and AVM resection surgery.

Keywords: AVM; fluorescence; indocyanine green; neurosurgery; resection; videoangiography.

Figure 1

A large right temporoparietal AVM is exposed (A). ICG videoangiography (B) demonstrates the early filling of the arterial feeders (red arrow) and delayed filling of arterialized veins (purple arrow); this technique can confirm the identity of these vessels more accurately especially if they are covered by thick arachnoid bands. This information can also guide the early steps of disconnection to start in the area where the concentration of feeding arteries is most (red arrow). The same AVM was analyzed via the use of FLOW 800 software. Please note the feeding arteries in red, arterialized veins in yellow, and normal veins in blue (C). Post-resection FLOW 800 analysis demonstrates that the primary vein is now blue (D).

Figure 2

Fluorescein videoangioram of a parietal AVM demonstrates the relative flow in different components of the AVM: feeding artery (red arrow), arterialized vein (purple arrow), and normal vein (blue arrow).