(a) The right side is cranial, and the left side is caudal. The dura and arachnoid are incised. The arachnoid web is still present as a restiform structure (black arrow). (b) After resection of the arachnoid web. (c) Hematoxylin and eosin staining shows fibrous tissue and microcalcifications. (d) Elastica-Masson staining shows epithelial tissue. (e, f) Postoperative sagittal and axial CT myelography show no spinal cord deviation, and the “scalpel sign” has vanished. The white line shows the T5/T6 disc level.