Intradural extramedullary arachnoid cyst in a 56-year-old woman with prior lumbar spine fusion who presented with chronic lower extremity sensory changes and back pain. (a, b) Sagittal (a) and axial (b) T2-weighted images demonstrate a posterior, nonspecific, prominent CSF space (*). (c, d) Axial (c) and sagittal (d) CT myelograms help confirm an intradural extramedullary arachnoid cyst (arrow) that is partially opacified by intrathecal contrast material and exerts mass effect on the adjacent spinal cord.
Complete spinal block in a 67-year-old man with prior spinal cord injury and lumbar spine surgery who presented with worsening bilateral lower extremity pain, with the right side affected more than the left. (a) Sagittal contrast-enhanced T1-weighted image demonstrates a hyperintense scar (arrow) at the L2-L3 intervertebral disk level. (b, c) Sagittal contrast-enhanced CT myelograms obtained after lumbar injection of contrast material (b) and after cervical injection (c) help confirm complete arrest of intrathecal contrast material at the L2-L3 intervertebral disk level (arrow), which is suggestive of complete spinal block.