Three patients (1 dog, 2 horses) are described where myelography was c
omplicated, purportedly by injection of contrast medium into the menin
ges superficial to the subarachnoid space, Contrast medium injected in
this location in a cadaver tended to accumulate dorsally within the v
ertebral canal, deep to the dura mater but superficial to the subarach
noid space, The ventral margin of the pooled contrast medium had a wav
y or undulating margin and the dorsal margin was smooth, pooled contra
st medium was believed to be sequestered within the structurally weak
dural border cell layer between the dura mater and arachnoid membrane,
or the so-called subdural space.