FIGURE 2.

A-P, Serial CT axial images at the C6 spinal segment before A through H and after I through P thoracic laminectomy and duraplasty in a patient with a history of instrumented fusion of a traumatic fracture dislocation at the T8-9 spinal level years before and subsequent development of post-traumatic syringomyelia (Sp-S). Images A and I were obtained without contrast and the other images were obtained at these intervals (hours) after intrathecal contrast administration (CT myelography), 0.6 B, J, 3 C, K, 5 D, L, 7 E, M, 9 F, N, 11 G, O, 23 H, P h. The white arrowheads A, I indicate the central syrinx. Myelogram dye enters the syrinx to a much great extent before surgery (black arrow, G compared to after surgery (white arrow, O. Q and R, Hounsfield units in this patient were measured in the subarachnoid space, spinal cord, and syrinx from the sequential CT axial images, and graphs were drawn of the mean and standard deviation of pixel values (error bars) in these regions of interest at each time point. The graphs confirm the visual impression that much more myelogram dye enters the syrinx before Q compared to after R surgery in syringomyelia associated with a spinal canal lesion (Sp-S).