FIG. 2.

A: An arcuate incision was made from the left T10 pedicle to the T11 pedicle. B: A lateral laminectomy of T10–11 and a facetectomy of T10–11 were performed between the muscles to expose the dura mater and T10 nerve root (asterisk). C: The dura mater was incised and opened, and the inside of the dura mater was observed using a 45° endoscope fixed to a UniARM. D: Lateral view of the spinal cord from the left lateral side, confirming the posterior median septum (double asterisks). E: When the ventral side was unfolded, the ASA (white arrows) was found to be descended, and an abnormal red vein was observed, identifying the AVS point (yellow arrow). F: Endoscopic clipping was attempted. G: The AVS site (yellow arrow) was carefully dissected. H: The AVS was blocked with endoscopic assistance.