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82 Section I: Diagnostics and Planning
disc herniations, and intramedullary neoplasms tend to be focal 5 Widmer WR. Iohexol and iopamidol: new contrast media for veterinary myelogra
lesions while inflammatory disease is often multifocal and may be phy. J Am Vet Med Assoc 1989;194:1714–1716.
associated with meningeal enhancement. Lack of signal from the 6 Widmer WR, Blevins W. Veterinary myelography: a review of contrast media,
adverse effects, and technique. J Am Anim Hosp Assoc 1991;27:163–177.
CSF on this sequence has also been associated with meningitis [40]. 7 Fatone G, Lamagna F, Pasolini MP, Potena A, Brunetti A. Myelography in the dog
Ischemia frequently affects one half of the spinal cord. with non‐ionic contrast media at different iodine concentrations. J Small Anim
Myelomalacia can occur with severe exogenous trauma or Pract 1997;38:292–294.
intervertebral disc herniation. Spinal cord swelling and opacifica 8 DeLahunta A, Glass E. Veterinary Neuroanatomy and Clinical Neurology, 3rd edn.
St Louis, MO: Saunders/Elsevier; 2008.
tion of the spinal cord during myelography can be seen in dogs with 9 Lamb CR. Common difficulties with myelographic diagnosis of acute interverte
myelomalacia [75]. Spinal cord opacification can be subtle, and bral disc disease in the dog. J Small Anim Pract 1994;35:549–558.
therefore CT post myelography may be a more sensitive indicator of 10 Barone G, Ziemer LS, Shofer FS, Steinberg SA. Risk factors associated with devel
myelomalacia than myelography alone. Characteristics of myelo opment of seizures after use of iohexol for myelography in dogs: 182 cases (1998). J
malacia on MRI are those of severe edema (T2 hyperintensity) or Am Vet Med Assoc 2002;220:1499–1502.
hemorrhage [56]. 11 da Costa RC, Parent JM, Dobson H. Incidence of and risk factors for seizures after
myelography performed with iohexol in dogs: 503 cases (2002–2004). J Am Vet Med
Assoc 2011;238:1296–1300.
12 McKee WM, Penderis J, Dennis R. Radiology corner: obstruction of contrast medium
Conclusions flow during cervical myelography. Vet Radiol Ultrasound 2000;41:342–343.
Although it is generally accepted that MRI is superior to myelogra 13 Kirberger RM, Roos CJ, Lubbe AM. The radiological diagnosis of thracolumbar
disc disease in the Dachshund. Vet Radiol Ultrasound 1992;33:255–261.
phy and CT for neuroimaging, it is important to recognize that for 14 McCartney WT. Lumbar myelography in 79 dogs, using different puncture sites.
many spinal problems all these tests have similar sensitivities and Vet Rec 1997;141:417–419.
specificities. Additionally, for certain problems such as spinal 15 Tilmant L, Ackerman N, Spencer CP. Mechanical aspects of subarachnoid space
trauma the superior spatial resolution of CT can be advantageous. puncture in the dog. Vet Radiol 1984;50:227–232.
Therefore, when MRI is not readily available or cost‐effective these 16 Kishimoto M, Yamada K, Ueno H, Kobayashi Y, Wisner ER. Spinal cord effects
from lumbar myelographic injection technique in the dog. J Vet Med Sci
other modalities remain appropriate options for imaging spinal dis 2004;66:67–69.
ease in the dog and cat. 17 Kirberger RM, Wrigley RH. Myelography in the dog: review of patients with con
Numerous studies have compared myelography, unenhanced CT, trast medium in the central canal. Vet Radiol Ultrasound 1993;34:253–258.
contrast‐enhanced CT, CT myelography, and MRI for the evalua 18 Lexmaulova L, Zatloukal J, Proks P, Dvorak M, Srnec R, Rauser P et al. Incidence of
seizures associated with iopamidol or iomeprol myelography in dogs with interver
tion of intervertebral disc disease [25,26,29–31,51]. All studies are tebral disk disease: 161 cases (2000–2002). J Vet Emerg Crit Care 2009;19:611–616.
limited by the fact that the gold standard used is surgery. It is not 19 Carroll GL, Keene BW, Forrest LJ. Asystole associated with iohexol myelography in
practical or ethical to explore all potential sites of intervertebral disc a dog. Vet Radiol Ultrasound 1997;38:284–287.
extrusion in clinical patients and it is possible, although unlikely, 20 Lamb CR. The dorsoventral cervical myelogram. Vet Radiol Ultrasound
1995;36:201–202.
that sites of intervertebral disc extrusion are not detected with any 21 Matteucci ML, Ramirez O III, Thrall DE. Radiographic diagnosis: effect of right vs.
modality and that false‐negative results occur. As a result surgery as left lateral recumbency on myelographic appearance of a lateralized extradural
a gold standard results in bias [26,44]. mass. Vet Radiol Ultrasound 1999;40:351–352.
In spite of these limitations it is generally accepted that MRI is the 22 Nykamp S, Scrivani P. Feline myelography. Vet Radiol Ultrasound 2001;42:532–533.
best imaging modality for the assessment of spinal cord disease and 23 Seiler G, Kinns J, Dennison S, Saunders J, Schwarz T. Vertebral column and spinal
cord. In: Schwarz T, Saunders J (eds) Veterinary Computed Tomography. Chichester,
when available and cost is not a concern should be the recommended West Sussex: Wiley‐Blackwell, 2011: 209–228.
test. However, CT, CT myelography, and myelography all have an 24 Kinns J, Malinowski R, McEvoy F, Schwarz T, Zwingenberger A. Special software
acceptable sensitivity and specificity in the detection of intervertebral applications. In: Schwarz T, Saunders J (eds) Veterinary Computed Tomography.
disc herniation and can be used when MRI is not available or afford Chichester, West Sussex: Wiley‐Blackwell, 2011: 67–74.
able. Additionally, the information from all modalities can be com 25 Hecht S, Thomas WB, Marioni‐Henry K, Echandi RL, Matthews AR, Adams WH.
Myelography vs. computed tomography in the evaluation of acute thoracolumbar
plementary and a multimodality approach may be required for some intervertebral disk extrusion in chondrodystrophic dogs. Vet Radiol Ultrasound
diseases. Although MRI can provide information regarding progno 2009;50:353–359.
sis, it has also been shown that the choice of imaging test does not 26 Newcomb B, Arble J, Rochat M, Pechman R, Payton M. Comparison of computed
correlate with patient outcome [45,59,76]. tomography and myelography to a reference standard of computed tomographic
myelography for evaluation of dogs with intervertebral disc disease. Vet Surg
2012;41:207–214.
Video clips to accompany this book can be found on 27 Sharp NJH, Cofone M, Robertson ID, DeCarlo A, Smith GK, Thrall DE. Computed
the companion website at: tomography in the evaluation of caual cervical spondylomyopathy of the Doberman
Pinscher. Vet Radiol Ultrasound 1995;36:100–108.
www.wiley.com/go/shores/neurosurgery 28 Hara Y, Tagawa M, Ejima H, Orima H, Fujita M. Usefulness of computed tomogra
phy after myelography for surgery on dogs with cervical intervertebral disc protru
sion. J Vet Med Sci 1994;56:791–794.
29 Dennison SE, Drees R, Rylander H, Yandell BS, Milovancev M, Pettigrew R, et al.
References Evaluation of different computed tomography techniques and myelography for the
1 Gibbons S, Macias C, De Stefani A, Pinchbeck G, McKee W. The value of oblique diagnosis of acute canine myelopathy. Vet Radiol Ultrasound 2010;51:254–258.
versus ventrodorsal myelographic views for lesion lateralisation in canine thora 30 Drost WT, Love NE, Berry CR. Comparison of radiography, myelography and
columbar disc disease. J Small Anim Pract 2006;47:658–662. computed tomography for the evaluation of canine vertebral and spinal cord
2 Tanaka H, Nakayama M, Takase K. Usefulness of myelography with multiple views tumors in sixteen dogs. Vet Radiol Ultrasound 1996;37:28–33.
in diagnosis of circumferential location of disc material in dogs with thoracolumber 31 Israel SK, Levine JM, Kerwin SC, Levine GJ, Fosgate GT. The relative sensitivity of
intervertebral disc herniation. J Vet Med Sci 2004;66:827–833. computed tomography and myelography for identification of thoracolumbar
3 Widmer WR, Thrall D. Canine and feline intervertebral disc disease, myelography, intervertebral disk herniations in dogs. Vet Radiol Ultrasound 2009;50:247–252.
and spinal cord diseases. In: Thrall D (ed.) Textbook of Veteirnary Diagnostic 32 Shimizu J, Yamada K, Mochida K, Kako T, Muroya N, Teratani Y et al. Comparison
Radiology, 5th edn. St Louis, MO: Saunders Elsevier, 2007. of the diagnosis of intervertebral disc herniation in dogs by CT before and after
4 Wheeler S, Davies J. Iohexol myelography in the dog and cat: a series of one hundred contrast enhancement of the subarachnoid space. Vet Rec 2009;165:200–202.
cases, and a comparison with metrizamide and iopamidol. J Small Anim Pract 33 Bettmann MA. Angiographic contrast agents: conventional and new media com
1985;26:247–256. pared. AJR Am J Roentgenol 1982;139:787–794.
