Canis ISSN: 2398-2942

Radiology: myelography

Contributor(s): Fraser McConnell

Indication

  • To diagnose and localize spinal cord compression.

Contraindication

  • Turbid or discolored CSF or inflammation or infectious CSF disease.
  • Coagulopathy.
  • Severe skin infection over site of injection.

Technical considerations

  • Aseptic spinal tap technique required.
  • Only use non-ionic iodine based contrast medium, general anesthesia mandatory.
  • Contrast rapidly dissipates from the subarachnoid space so examination should be performed quickly.
  • Myelography should follow plain survey radiography.
  • The CSF should be collected for analysis Cerebrospinal fluid: sampling. If CSF discolored or turbid, myelography should not be performed.

Cisternal injection

  • The head should be elevated during myelography to minimize cranial extension of contrast media.
    • Preferred for cervical cord and lumbosacral evaluation (better delineation/ lack of epidural contamination in LS area).
    • Cisternal puncture myelography has higher incidence of post myelography seizures, presumably due to cranial flow of contrast medium into ventricular system.
    • Compressive spinal lesions force the contrast media towards the ventricles which increases the risk of seizures Seizures and prevents outline of spinal lesion.

Lumbar injection

  • Preferred for visualization of thoracolumbar region.
  • Generally lower seizure incidence.
  • Can be forced to pass a compressive cord lesion under pressure which facilitates outline a lesion surrounded by an extensive spinal cord edema.
  • Doses: 0.30ml/kg body weight for cisternal and 0.30-0.45 ml/kg body weight for lumbar injection.
  • Contrast media is heavier then CSF so can be moved within the subarachnoid space by altering the positioning of the animal, eg elevation of the head and hindquarters will cause the contrast to pool in the caudal cervical spine.

Myelographic contrast media

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Principles of interpretation

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Extradural compression

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Intradural-extramedullary lesion

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Intramedullary lesions

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Further Reading

Publications

Refereed papers


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