A 63-year-old woman developed two-level ASD with myelopathic symptoms at the 8th year after the primary surgery and underwent PDF with instrumented fusion as a revision surgery. a Lateral radiograph after the primary surgery showing that ACCF was performed at C5. b MRI before revision surgery showing a large disc extrusion behind the C3 vertebral body accompanied by ISI on the spinal cord at C3–C4 and C6–C7. c Lateral radiograph after revision surgery showing that posterior decompression with instrumented fusion was performed at C3–C7. d MRI at 2nd year postoperatively showing resorption of the herniated disc and release of spinal cord compression but with residual ISI at C6–C7.