A myelogram is an injection of dye in and around the nerve roots followed by an x-ray. A computed tomography (CT) myelogram combines the use of a CT-scan and a myelogram. This document addresses the use of CT myelography.

Medically Necessary:

A CT myelogram is considered medically necessary to evaluate the following when an MRI is either not feasible, is contraindicated or is inconclusive for diagnosis:

1. Suspected spinal fluid leak; or
2. Suspected dural tear; or
3. Suspected nerve root herniation or avulsion; or
4. Suspected intervertebral disk herniation; or
5. Suspected spinal arterio-venous malformation; or
6. Suspected arachnoiditis; or
7. Suspected syringomyelia; or
8. Suspected neuro-compression ; or
9. Suspected epidural abscess or mass; or
10. Suspected intradural mass; or
11. Suspected tethered cord.

Not Medically Necessary: 

A CT myelogram is considered not medically necessary for all other indications.

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A myelogram is a specialized x-ray examination of the spinal cord, nerves, and other tissues within the spinal canal. The procedure involves injecting a contrast solution (a water-soluble dye) to help provide an outline of the spinal cord and nerve roots. The absence of this solution in a specific area, known as a filling defect, can indicate that the spinal cord or nerve root is being pinched or compressed.

Myelography is frequently combined with computed tomography (CT). This technique is called a CT myelogram. Compared with traditional myelography, CT myelography can provide excellent nerve detail and is at least as sensitive and specific in the diagnosis of herniated lumbar discs. Whereas a traditional plain film myelogram was limited in the ability to identify the anterior neural foramina, this information is easily obtained via a CT myelogram.

Currently, most myelography is performed using water-soluble, non-ionic contrast materials. Water-soluble agents offer a two-fold advantage: there is no risk of secondary arachnoiditis, and CT can be utilized in individuals who cannot undergo MRI and have previously had plain film myelography in order to identify the spinal canal and neural foramina.

Peer Reviewed Publications:

1. Ahmed M, Modic MT. Neck and low back pain: neuroimaging. Neurol Clin. 2007; 25(2):439-471.
2. Bartynski WS, Lin L. Lumbar root compression in the lateral recess: MR imaging, conventional myelography, and CT myelography comparison with surgical confirmation. AJNR Am J Neuroradiol. 2003; 24(3):348-360.
3. Delamarter RB, Ross JS, Masaryk TJ, et al. Diagnosis of lumbar arachnoiditis by magnetic resonance imaging. Spine. 1990; 15(4):304-310.
4. Koch C. Spinal dural arteriovenous fistula. Curr Opin Neurol. 2006; 19(1):69-75.
5. Kumar N, Lindell EP, Wilden JA, Davis DH. Role of dynamic CT myelography in identifying the etiology of superficial siderosis. Neurology. 2005; 65(3):486-488.
6. Modic MT, Masaryk T, Boumphrey F, et al. Lumbar herniated disk disease and canal stenosis: prospective evaluation by surface coil MR, CT, and myelography. AJR Am J Roentgenol. 1986; 147(4):757-765.
7. Polston DW. Cervical radiculopathy. Neurol Clin. 2007; 25(2):373-385.
8. Richmond B, Ghodadra T. Imaging of spinal stenosis. Phys Med Rehabil Clin N Am. 2003; 14(1):41-56.
9. Rinaldi F, Cioffi FA, Columbano L, et al. Tethered cord syndrome. J Neurosurg Sci. 2005; 49(4):131-135.
10. Russell EJ. Computed tomography and myelography in the evaluation of cervical degenerative disease. Neuroimaging Clin N Am. 1995; 5(3):329-348.
11. Schellinger D. Patterns of anterior spinal canal involvement by neoplasms and infections. AJNR Am J Neuroradiol. 1996; 17(5):953-959.
12. Shafaie FF, Wippold FJ 2^nd, Gado M, et al. Comparison of computed tomography myelography and magnetic resonance imaging in the evaluation of cervical spondylotic myelopathy and radiculopathy. Spine. 1999; 24(17):1781-1785.
13. Silbergleit R, Brunberg JA, Patel SC, et al. Imaging of spinal intradural archnoid cysts: MRI, myelography and CT. Neuroradiology. 1998; 40(10):664-668.
14. Tilson ER, Strickland GD, Gibson SD. An overview of radiography, computed tomography, and magnetic resonance imaging in the diagnosis of lumbar spine pathology. Orthop Nurs. 2006; 25(6):415-420.

Government Agency, Medical Society, and Other Authoritative Publications:

1. American Academy of Neurology (AAN) Transverse Myelitis Consortium Working Group. Proposed diagnostic criteria and nosology of acute transverse myelitis. Neurology. 2002; 59(4):499-505.
2. American College of Radiology. ACR Practice Guideline for the Performance of Myelography and Cisternography. (2008) Available at: http://acr.org/SecondaryMainMenuCategories/quality_safety/guidelines.aspx. Accessed on October 28, 2009.
3. Browner: Skeletal Trauma: Basic Science, Management, and Reconstruction. 3rd ed. St. Louis: W.B. Saunders. 2003. Chapter 26: Spinal Imaging.
4. Goetz C, Pappert E, eds. Textbook of Clinical Neurology, 2nd ed. Philadelphia: WB Saunders, 2003. pp 447-450.
5. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 4th ed. Orlando: Churchill Livingstone, Inc. 2001. Chapter 102: The Imaging of Spinal Pathology.

CT Myelogram
Myelography