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. Confirma
tion 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 ex
tension of the contrast medium.