PMC4628161_01
Left: Initial preoperative three-dimensional computed tomography (CT) angiography demonstrating a distal posterior inferior cerebellar artery aneurysm on the cortical segment. The posterior inferior cerebellar artery and the anterior inferior cerebellar artery were branching from almost the identical segment of the vertebral artery. Right: The post-operative lateral view of the left vertebral digital subtraction angiography showing good patency of the distal posterior inferior cerebellar artery and no residual aneurysm is seen.
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F1
Three-dimensional computed tomography (CT) angiography (Fig. 1, left) revealed a distal aneurysm (4 mm) in the cortical segment of the left PICA. The blood flow through the distal/peripheral part of the PICA was confirmed by cerebral angiography (Fig. 1, right).
Left: The microscopic findings of the surgical field. The tonsillomedullary segment of the left posterior inferior cerebellar artery was temporary clipped. Middle: An ICGVAG image taken 16 s after the ICG infusion. The peripheral left posterior inferior cerebellar artery (white arrow) was enhanced from the collateral circulation. The proximal side of the posterior inferior cerebellar artery was not enhanced (arrowhead), because of the temporary clip. Right: An ICGVAG image taken 22 s after the ICG infusion just after the removal of the temporary clip. The enhancement of the peripheral left posterior inferior cerebellar artery (arrowhead) was diminished (white arrow) just after the removal (arrowhead) of the clip. ICGVAG: indocyanine green videoangiography.
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On the brain surface, two arteries believed to be the distal PICA were identified (Fig. 2, left). The peripheral segment of the PICA was satisfactorily dyed after an injection of ICG, and after removal of the temporary clip, the level of dye in the peripheral PICA segment temporarily diminished (Fig. 2, right).
The microscopic findings of the aneurysm after clipping. The white arrow indicates the proximal artery, and the white arrowhead indicates the distal artery.
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Before and after the clipping (Fig. 3) of the aneurysm, the preservation of the blood flow to the distal artery was verified using ICGVAG.
PMC4628161_02
Intraoperative ICGVAG images. Image A was captured 11 s after the ICG infusion before the removal of the temporary clip. The frontal peripheral middle cerebral artery (arrowhead) has been thinly enhanced. The temporal peripheral middle cerebral artery (arrow) has been thickly enhanced. Image B was captured just before the removal of temporary clip. The frontal peripheral middle cerebral artery (arrowhead) and the temporal peripheral middle cerebral artery (arrow) have been enhanced at the same level. Image C was captured just after the removal of the temporary clip. The enhancement of the frontal peripheral middle cerebral artery (arrowhead) was diminished just after the removal of the clip. ICGVAG: indocyanine green videoangiography.
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The frontal branch of the M4 was thinly dyed and, immediately, another branch of the M4 was thickly dyed by an injection of ICG; after removal of the temporary clip, the level of the dye in the frontal branch of the M4 temporarily increased and diminished (Fig. 4 A-C).
Fluorescent intensity curve with the Carl Zeiss FLOW 800 system (Carl Zeiss Co., Tokyo). The pink curve indicates the frontal peripheral middle cerebral artery and the red curve indicates the frontal peripheral middle cerebral artery. The blue circle on the pink curve indicates a temporary change of intensity just after the removal of the temporary clip.
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The flow 800 analysis indicated a temporary change of intensity of the frontal branch of the M4 (Fig. 5).
PMC4628161_03
Upper left: Anterior posterior view of the initial digital subtraction angiography demonstrating a distal posterior inferior cerebellar artery aneurysm on the cortical segment. Upper right: An ICGVAG image taken 22 s after ICG infusion. The peripheral left posterior inferior cerebellar artery (white arrow) vessel has been thinly enhanced. Lower left: An ICGVAG image just after the removal of the temporary clip. The strength of the enhancement of the peripheral left PICA (white arrow) was changed. Lower right: The microscopic findings of the aneurysm before clipping. The white arrow indicates the proximal artery, and the white arrowhead indicates the aneurysm. ICGVAG: indocyanine green videoangiography, PICA: posterior inferior cerebellar artery.
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Digital subtraction angiography (Fig. 6, upper left) revealed a distal aneurysm (5 mm) in the distal left PICA. The peripheral segment of the PICA was thinly dyed after an injection of ICG, and after removal of the temporary clip, the level of dye in the peripheral PICA segment temporarily increased and diminished (Fig. 6, upper right and lower left). Before (Fig. 6, lower right) and after the clipping of the aneurysm, the preservation of the blood flow to the distal artery was verified using ICGVAG.