Utility of Indocyanine Green Video Angiography for Sylvian Fissure Dissection in Subarachnoid Hemorrhage Patients - Sylvian ICG Technique

Abstract

Indocyanine green (ICG) emits fluorescence in the far-red domain under light excitation. ICG video angiography (ICG-VA) has been established as a useful method to evaluate blood flow in the operative field. We report the usefulness of ICG-VA for Sylvian fissure dissection in patients with subarachnoid hemorrhage (SAH). Subjects comprised 7 patients who underwent ICG-VA before opening the Sylvian fissure during neck clipping for ruptured cerebral aneurysm. We observed contrasted Sylvian veins before opening the Sylvian fissure using surgical microscopes. This procedure was termed "Sylvian ICG". We observed ICG fluorescence quickly in all cases. Sylvian veins that appeared unclear in the standard microscopic operative field covered with subarachnoid hemorrhage were extremely clearly depicted. These Sylvian ICG findings were helpful in identifying entry points and the dissecting course of the Sylvian fissure. At the time of clipping, no residual fluorescence from Sylvian ICG was present, and aneurysm clipping was not impeded. Sylvian ICG for SAH patients is a novel technique to facilitate dissection of the Sylvian fissure. We believe that this technique will contribute to improved safety of clipping surgery for ruptured aneurysms.

Keywords: Sylvian fissure; Sylvian veins; indocyanine green video angiography; subarachnoid hemorrhage.

Fig. 1.

Case 2. Illustrative case of a patient with ruptured left middle cerebral artery aneurysm. (A) Intraoperative microscopic findings of the Sylvian fissure before Sylvian ICG. Sylvian veins are unclear because of diffuse subarachnoid. (B) Intraoperative view from the same position after Sylvian ICG, demonstrating Sylvian veins extremely clearly. The double arrow shows safety space between the superficial Sylvian veins for dissection, confirming the true Sylvian fissure. The red circle shows tortuosity and junction of the veins. (C) The yellow line represents the course of dissection selected.

Fig. 2.

Case 2. The venous phase of preoperative cerebral angiography (A) and intraoperative Sylvian ICG (B) are compared. Sylvian ICG accurately represent simple Sylvian veins. The white square in Fig. 2A shows the same part of the Sylvian vein observed by Sylvian ICG.

Fig. 3.

Case 5. Illustrative case of a patient with ruptured right posterior communicating artery aneurysm. (A) Intraoperative microscopic findings of the Sylvian fissure before Sylvian ICG. Sylvian veins are unclear because of diffuse subarachnoid hemorrhage. (B) Intraoperative view from the same position after Sylvian ICG demonstrates the Sylvian veins extremely clearly. The double arrow shows safety space between the superficial Sylvian veins for dissection. The red circle shows tortuosity and junction of the veins. Reflection of the microscopic light has no influence. (C) The yellow line represents the course of dissection selected.

Fig. 4.

Case 5. The venous phase of preoperative cerebral angiography (A) and intraoperative Sylvian ICG (B) are compared. Sylvian ICG accurately represent complex Sylvian veins. The white square in Fig. 4A shows the same part of the Sylvian vein observed by Sylvian ICG.

Fig. 5.

The schemas of intraoperative findings before and after Sylvian ICG. Before the procedure, it is difficult to identify Sylvian veins because they are of the same color as the surrounding hematoma (A). After Sylvian ICG, it is easy to identify superficial Sylvian veins (B). Superficial Sylvian veins are shown in white (arrows) and surrounding arachnoid with hematoma is shown in black (arrow head). After arachnoid incision, it is easy to identify deep Sylvian veins due to hematoma is washed away (C).