Fig 2.

Examples of the dorsal indentation demonstrated in the upper thoracic spine of several patients in the article. A and B, Examples of increased cord signal above the level of indentation. C, Dorsal indentation without cord signal changes. D, A case in which there is extensive cord signal change and syringomyelia above the level of indentation. E and F, CT myelograms. E, An example of the upside down scalpel sign, where cord expansion occurs inferior to the level of dorsal indentation. Note that previous laminectomies are present in E.