Subdural injection of contrast medium as a complication of myelography.

In a retrospective evaluation of 654 canine and feline myelograms, 58 were found to have been complicated by injection of the contrast medium into the subdural space. The medium was present predominantly dorsal to the spinal cord, with a sharp dorsal border and an undulating ventral border. Confirmation that this myelographic appearance was due to subdural localisation was achieved using fresh cadavers injected with contrast medium labelled with Indian ink. It was further showed that the dorsal accumulation of contrast medium was due to the denticulate ligaments which restricted the ventral extension of the contrast medium.