Target Bypass Using Indocyanine Green Flash Fluorescence for the Large Aneurysm Buried in the Brain at the Distal Middle Cerebral Artery

Abstract

Aneurysms buried in the brain at the distal M3 segment of the middle cerebral artery (MCA) cannot be recognized. They frequently have nonsaccular morphology that necessitates bypass and trapping of the superficial temporal artery (STA) to the M4 segment of the MCA (M4); however, identification of the recipient M4 is difficult. We introduce the “flash fluorescence” technique using indocyanine green-videoangiography (ICG-V) to identify an appropriate recipient M4. This technique is based on the analysis of differences in the timing of filling of M4 observed on serial ICG-V. First, correct identification of the M3 as the proximal artery for the aneurysm is necessary during preoperative cerebral angiography. Second, a wide dissection of the Sylvian fissure should be performed to expose the proximal M3. Under temporary clipping of the proximal M3, the candidate recipient M4 is not enhanced. After removing the temporary clip, the M4 is enhanced and identified as the recipient M4 for STA-M4 bypass.